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Why do we try to save Tiger if it kills more than 4 humans a year?

Environmental Science solution --Tribhuwan University-Bsc 1st year
BSC 1st year microsyllabus Course contents and Elaboration UNIT-1 Course : Ecology, history and scope of ecology and its relation with other sciences, evolution of the biosphere, concept of ecosystems and their types :forests, grasslands, arid lands and wetlands, concept of primary and secondary productivity, food chain, food web, tropic structure and ecological pyramids, biogeochemical cycles, nutrient cycling, cycling of organic nutrients, major parameters of population ecology; applied ecology, biological conservation, conservation of natural resources, causes of forest degradation and its consequences, in-situ national parks and wildlife conservation, ex-situ-germ plasma conservation, Ecology and its relevance to human society. Elaboration Historical background information on ecology, meaning and definition of atmosphere, lithosphere, hydrosphere, biosphere, ecosphere. Ecology, auto ecology and synecology, Scope of ecology, contribution of ecology in socio-economic development, human welfare, agriculture, forestry, grasslands, fishery, wildlife, soil conservation, pest management and water supply. Relation of ecology with other sciences such as natural science, physical science, geological science, atmospheric science and social sciences.. Relation of ecology with other sciences such as natural sciences, physical science, geological science, atmospheric science and social sciences. Evolution of biosphere: origin of anaerobic heterotrophs, simple autotrophs, role of allogenic and autogenic forces, ozone layer formation in the atmosphere, development of simple and complex life forms in terrestrial and aquatic environment, co-evolution of community. Concept of ecosystem and their types: Definition of ecosystem, basic concept of ecosystem, definition of biome, types of ecosystem: forest, grassland, desert and wetland climatic conditions, characteristics producer, consumer and decomposers of forest, grassland, desert and wetland ecosystems. Concept of primary and secondary productivity: basic concept of primary productivity with definition, common methods used to estimate primary productivity in terrestrial and aquatic ecosystems, basic concept of secondary productivity, role ofautochthonous and allochthonous materials in the productivity. Food chain and food web :definition of food chain and food web, differences between food chain and food web, principles of energy, movement and nutrient, circulation in the ecosystem, application of thermodynamic first and seconds laws during the movement of energy, Examples of food chain and food web in terrestrial and aquatic ecosystem, grazing food chain and detritus food chain, justify that the shorter the food chain, the greater the available energy, ecological pyramids of aquatic ecosystem, forest ecosystem, desert ecosystem and grassland ecosystem. Biogeochemical nutrient cycling and cycling of organic nutrients: basic concept and definition of biogeochemical cycles, types of biogeochemical cycle, significance of biogeochemical cycle, need of nutrient cycling and cycling of organic nutrients in the environment, sources of nutrients in the environment, role of producers, consumers and decomposers in nutrient cycling. Major parameters of population ecology: definition of population, characteristics features of population, difference between an individual and population, population density, relative abundance, natality, mortality, age distribution, common methods used to determine density, relative abundance, natality and mortality. Applied ecology: basic concept of natural resources, definition of natural resource, renewable and non-renewable natural resources, importance of natural resources, basic concept of biodiversity, basic concept and definition of biological conservation, conservation of natural resources, causes of forest degradation, effects of forest degradation such as soil erosion landslide, sedimentation in rivers, streams and lakes and climatic changes, in-situ conservation national parks, wildlife conservation, ex-situ germ plasma conservation, application of ecological principles in human society. Unit 2 Course Population and community analysis: species interaction, ammensalism, commensalism, cooperation, mutualism, competition and its types: space, light, carbon dioxide, nutrients, water, intraspecific and interspecific competition, growth and regulation of community succession, climax, heterogeneity and equitability, biodiversity: general concept, wildlife concept, wildlife and vegetation of Nepal. Adaptation, population differentiation and evolution, origin and significances of adaptation, ecad, ecotypes, ecocline, speciation, biotic community concept, intercommunity classification and concept of ecological dominance. Elaboration Species interaction: concept of interactions, positive interaction and negative interaction, positive interaction-commensalism, cooperation, mutualism; negative interaction, predation, parasitism, competition. interspecific and intraspecific competition, justify that competition occurs for space, light, carbon dioxide, nutrients and water, ecological niche, competitive exclusion and competitive displacement theories with justification, lotka-voltera model of competition. Population growth: intrinsic rate of natural increase, j-shaped growth form and S – shaped growth form with justification, concept of carrying capacity, methods used to calculated population growth. Succession and climax : concept of community, definition of succession, concept of autotrophic succession, heterotrophic succession, autogenic succession and allogenic succession, process of succession with example, concept of climax, monoclimax theory, polyclimax theory and climax pattern theory. Heterogeneity and equitability: concept of spatial heterogeneity, macrospatial heterogeneity and microspatial heterogeneity with suitable examples, concept of equitability, measurement of equitability. Biodiversity: concept of biodiversity, species diversity, genetic diversity and ecosystem diversity, and methods to measure species diversity, importance of biodiversity, role of biodiversity in the classification of ecosystems. Vegetation and wildlife of Nepal: concept of seven natural zones of Nepal – Terai including Bhabar, foothills, Mahabharat range, midlands, Himalayas, inner Himalayas, arid zone, vegetation zones of Nepal, common vegetation of tropical, subtropical, temperate, sub alpine and alpine zone, concept of wildlife of Nepal found in different climatic zones. Adaptation: concept of adaptation, significances of adaptation, adaptation to climatic factors, edaphic factors and light factor, population differentiation and evolution, basic concept of ecotype, genetic variations within the species due to edaphic and climatic factors, concept of ecad and ecocline, concept and definition of speciation, convergence, allopatric speciation, sympatric speciation, processes involved in speciation. Biotic community and inter community classification :concept of biotic community, major and minor communities, community classificationaccording to structural feature, physical habitat and functional features, zonal approach and gradient analysis approach for the classification of community within the geographical region. Ecological dominance: concept of ecological dominance, importance of ecological dominance in intra community classification, common methods used for the analysis of dominance index. UNIT-3 Course Ecosystem analysis: concept of ecological organization, ecosystem energetics. Components of ecosystems, ecosystem development: patterns and processes. Community level of organization, Quantitative and qualitative study, concept of ecotones and edge effect. Ecological indicators. Biogeochemical cycles: nitrogen, carbon, phosphorous and sulphur; concepts of productivity and photosynthesis, productivity of agro-ecosystems .methods of studying productivity and photosynthesis, productivity of agro-ecosystem. Methods of studying productivity in ecosystems, human impacts on ecosystem- major impacts and their implications in general. Elaboration Concept of ecological organization at the population and community levels. Ecosystem energetics : source of energy for ecosystem, distribution of solar energy, types of solar radiation reaching to earth’s surface, behavior of energy, characteristic of energy movement, P and R ratio, ecological efficiency, relationship between solar radiation and gross and net production, simple energy flow model, y-shaped energy flow model, universal model of ecological energy flow. Concept of ecosystem, components, development and processes: structure and functions of an ecosystem. Community level of organization: quantitative and qualitative study of community, characteristic features of community, pattern in community, concept of ecotone and edge effect, uniform habitat, mixed habitat. Concept of ecological indicators: important consideration with reference to ecological indicators, definition of euryhydric, stenohydric, eurythermal, stenothermal, euryphagic, stenophsgic, euryecious, stenoecious, euryhaline and stenohaline, common plants and animals used as ecological indicators to know the status of ecosystems. Biogeochemical cycles : definition of biogeochemical cycle ,types of biogeochemical cycle ,circulation of nitrogen, carbon, carbon, phosphorous, NPP/GPP ratio , NCP/GPP ratio, productivity of agro-ecosystem, man’s use of primary production, common methods for the measurement of primary productivity ,harvest method, oxygen method, carbon dioxide method and chlorophyll method, common methods for the measurement of secondary productivity, biomass method. Human impacts on ecosystems: deforestation, loss of wildlife, desertification, pollution, soil erosion, greenhouse effect, global warming, ozone layer depletion. UNIT-4 Course Microbial ecology : distribution of microorganisms in the environment .e.g. actinomycetes, cyano-bacteria, fungi, protozoa .waterborne pathogens, decomposers, biodeterioration of organic compounds, waste and water treatment, air pollution, microbial interaction, effect of microorganisms in food, microorganisms as food, growth and death of microorganisms. Elaboration Concepts of microbes, general features of actinomycetes, cyanobacter, fungi and protozoa, distribution of microorganism e.g. Actinomycetes, cyanobacter, fungi and protozoa in soil, mud, water and air, role of microorganisms found in soil, mud, water and air. Water borne pathogens: Aeromonas hydrophilic, vibrio cholerae, Salmonella enteriditis, Salmonella typhii, Shigella, Yersinia enterocolitica, Enterobacter coli, Glardia lamblica, Acanthamobea and Entamoeba histolytica. Characteristics features of vibrio cholerae, Salmonella coli, Giardia lamblica and Entamoeba histolytica and diseases caused by these microorganisms, preventive methods for diseases, Salmonella and coliform bacteria as indicators of water quality. Decomposers: cellulose decomposers (fungi, bacteria and Actinomycetes), Hemicelluloses decomposers (fungi, Bacteria and streptomycetes) and lignin decomposers (Fungi and Bacteria). Organic matter decomposition: composition of litter, carbon assimilation and immobilization, mineralization and immobilization of nitrogen, humus and humic acids factors affecting organic matter decomposition, relationship between carbon and nitrogen in organic matter decomposition. Waste treatment: Kinds of wastes, treatment of organic wastes – composting, factors affecting composting and biogas production –solubilisation, acidogenesis, and methanogenesis, factors affecting methane formation. Sewage treatment –sewage microorganisms, small scale sewage treatment – cesspools and septic tanks. Water treatment: sedimentation, filtration and Disinfection. Air pollution: common microbes that cause air pollution, diseases caused by microbes found in polluted air, air pollution control Microbial interaction: causes of microbial interactions, clay – humus- microbe interaction, destructive and beneficial interactions, plant –microbe interactions, animal –microbe interactions and microbe –microbe interactions, significances of interactions. Effect of microorganisms in food: microbial contaminations and spoilage of meats, spoilage of fresh meats, cured meat, dried meat, spoilage of fish, factors affecting kind and rate of spoilage, control of spoiling microorganisms. Microorganisms as food: criteria used for the selection of microorganisms for fermentation, pure culture, starter culture, fermentation role of microorganism in the production of yoghurt, butter milk, butter and cheese. Growth and death of organisms: growth in continuous, culture and butch culture, factors affecting the microbial growth, death of microbes. UNIT-5 Course Environmental earth sciences: conceptual framework of earth as a closed system. Earth material and processes, the internal structure of the earth, evolution of the planetary surface, rocks and minerals, their classification and abundance. Geological agents of change, wind water, ice, tectonism, volcanism, etc. River flooding, landslides and mass wasting, earthquakes and volcanic activity. man – environment interaction, water resources, land use and waste disposal, mining and its effects, geology and health. Elaboration Concept of natural life-supporting systems, spheres of the earth, dynamic interactions among spheres, biosphere and regolith, the earth’s system concept, conceptual framework of earth as a closed system with boundaries that do not permit the exchange of matter, emphasis should be given that we are living in a closed system. Earth’s process: concept of exogenous process and endogenous process, concept of earth’s material with examples. internal structure of the earth; the crust sial and sima, the mantle –upper and lower mantle and the core –outer core, middle core and inner core, density break, gravity break, seismic discontinuity, Repetti discontinuity, physical and chemical composition of crust, mantle and core, evolution of the planetary surface. Rocks and minerals: properties of rock, igneous rock, sedimentary rock  and metamorphic rock, rock –cycle, uniformitarianism and rock cycle, properties of mineral-physical and chemical, composition of mineral, common minerals – silicate minerals, oxides and other minerals, classification and abundance of minerals. Geological agents of change: wind erosion, transportation and deposition, deflation, Hamada, deflation –hollows, lag deposits, abrasion, yardang, ventifacts, pedestrl rock, zeugen, attrition, millet – seed sand, suspension, leoss, ripples, sand hill, sand dunes. Water –runoff, hydraulic action, abrasion, attrition, cavitations, corrosion, pot holes, water falls, river valleys, gorged. Ice-formation of ice, glacier movement, mountain glacier, piedmont glacier, continental ice sheets, plucking rasping, avalanching, transportation, unstratified deposits and stratified deposits. Tectonism: concept of tectonic movement, folds, faults, joints, unconformities River –flooding: causes of flood, effects of food on the environment and flood control –structural methods, non-structural methods, watershed management Landslide: concept of landslides, debris slide, debris fall, rockslide slump, creep, rock fall, talus, causes of landslide, effects of landslide on the environment and preventive measures to control landslides. Mass –wasting: concept of mass –wasting, slow-flowage, soil creep, talus creep, rock creep, rock –glacier creep, solifluction, rapid flowage, earth floe, mud flow, debris avalanche, subsidence. Earthquake: concept of earthquakes; causes of earthquakes, seismic waves, magnitude of earthquakes, location of epicenter, effects of earthquakes, geographic distribution of earthquakes, precautionary measures. Volcanic activity: causes and formations of volcanoes, continuity of eruption, nature of eruption, mode of eruption, volcanic products, istribution of volcanoes, important features associated with volcanoes, effects of volcanic activity on the environment. Man –environment interaction: over exploitation of natural resources, deforestation accelerating the geological processes like soil erosion, landslides, sedimentation, flood etc. environmental degradation and its impact. Water resources: concept of water resources, importance of water resources, water resources of Nepal, surface water run off, groundwater, impacts of excessive groundwater withdrawal, water management. Land use and water disposal: land use classification, production of waste, nature of waste, solid waste, liquid waste, hazardous waste, radioactive waste, waste management, contamination in geological environment. Mining and its effect: concept of mining, environmental impacts of mining. Geology and health: effects of chemical elements (trace elements) in the environment – contamination of soil, water, air, impacts of environmental degradation on health. UNIT-6 Course Principles of soil science: soil genesis: weathering of rocks, factors of soil formation. Soil profile development, chemical and mineralogical composition of soil, composition of primary minerals in soil, soil organic matter: sources, composition, microbes and microbial decomposition of organic matter, humus formation, nature and properties of humus, major soil types of Nepal. Significances of C: N ratio: soil reaction: soil colloidal system, cation and anion exchange phenomena. Soil pH, buffering capacity, soil acidity, soil alkalinity, salinity formation, major plant nutrients and trace elements, soil fixation of plant nutrients .soil water:- different forms, hygroscopic, capillary and gravitational movement of soil water under saturated and under saturated conditions. Soil aeration: composition of soil air, gaseous exchange between atmosphere and soil air soil atmosphere: absorption and loss of heat, heat of vaporization and thermal conductivity through a soil profile. Elaboration Soil genesis:-Definition of soil, concept of weathering processes, geochemical weathering, pedochemical weathering, physical weathering – effects of temperature, frost action, crystal growth, exfoliation, action of plants and animals, chemical weathering – hydration, carbonation, oxidation, action of plants, factors that influence soil formation – climate, living organisms, nature of parent material, texture and structure, chemical and mineralogical composition, topography of area and time that parent materials are subjected to soil formation, soil profile development – formation of horizons – organism and organic matter, nutrient recycling, role of water, inherited character, soil horizon - 0, A, E, B, C and R composition of minerals in soils, chemical composition of soil, soil organic matter: sources, composition, microbes, conditions affecting the growth of soil microbes-oxygen, moisture, temperature and organic matter requirements, exchangeable calcium and pH relationships, soil microbes: Cocci, Bacilli, Spirilli, Actinomycetes, fungi (Ascomycetes, zygomycetes, Basidiomycetes ), detail information on zygomycetes, conditions suitable for zygomycetes, role of zygomycetes, mycorrhizae, algae (cayanobacteria, chlorophyceae, chrysophyceae, Bacillariophyceae), protozoa (flagellates, Amoebae, ciliates ), microbial decomposition of organic matter : decomposition process, factors affecting decomposition – temperature, water nutrients and soil texture, humus, concept of carbon/nitrogen ratio, significances of C:N ratio with examples. Major soil types of Nepal : soils commonly found in Nepal –entisols, inceptisols, spodosols, mollisols, alfisols, soil occasionally found in Nepal –ultisols, aridosols, histosols, detail description of soils commonly found in Nepal. Soil reaction: concept of soil reaction, soil colloidal systems, types of colloidal matter,  silicate clays, iron and aluminum oxide clays, colloidal organization, differences between humus and inorganic micelles, adsorbed cations, concept of cation exchange, influence of lime and fertilizer, cation exchange capacity (CEC), factors  affecting CEC, anion exchange, concept of soil pH, importance of soil pH, buffering capacity of soil, soil acidity and alkalinity, factors responsible for acidity of soil, importance of buffering salinity formation, saline soil ,saline-sodic soil, sodic soil, effects of salinity, concept of sodium adsorption ratio (SAR), describe the methods for the calculation of SAR and exchangeable sodium percentage (ESP). Major plant nutrients and trace elements: concept of essential macronutrients and micro nutrients with their natural sources, concept of nutrients that limit the growth of plants, soil fixation of plant nutrients. Soil water: different forms (gravitational water, capillary water, hygroscopic water), importance of soil water, movement of soil water –saturated flow and unsaturated flow, factors that determine the flow of water, factors that control the rate of water movement into the soil infiltration rate, field capacity. Soil aeration : concept of soil aeration, biological processes in the soil that utilize oxygen, soil aeration problems in the field, composition of soil air, gaseous exchange between the soil and atmosphere, mass flow and diffusion, factors affecting soil aeration, soil temperature. Absorption and loss of heat: concept of absorption and loss of heat by soil, factors related to these processes – climate, color ,slope, vegetation cover, specific heat of soil; heat of vaporization, (thermal conductivity through a soil profile ). UNIT-7 Course Environmental chemistry :techniques and calculation in volumetric and gravimetric analysis, errors and statistical methods in chemical analysis, potentiometric, conductometric, electrometric titrations, electrolytic and calorimeter analysis, theory and methods of air, water, gases, hydrocarbon, pesticides, organic and inorganic herbicides,  biological control of pests, soil and organic sample analyses. Elaboration Techniques and calculation in volumetric and gravimetric analysis: Requirements for titrations, the chemistry of titrations, titration volumetric calculation, titration curves and PKa values, indicators, oxidation-reduction titrations, precipitation titrations, complexometric titrations, buffers, overview of gravimetric methods, weighing technique, desirable precipitate properties, the mechanism of precipitation of ionic compounds, co-precipitation of interferences, minimizing contaminations of precipitates, stoichiometric and gravimetric factors. Errors and statiscal methods in chemical analysis: measuring errors, absolute, relative measures, precision and accuracy, the normal (Gaussian) distribution, properties of Gaussian distribution, standard deviation, significant figures (digits). Potentiometer titration: working principle, method and applications (Neutralization, redox and precipitation reactions) Conductometric titration: working principle, method and applications (titration between strong acid Vs strong base and titration between strong base Vs weak acid), Brief introduction to electrometric titrations. Energy, wavelength, frequency and temperature, absorption spectrometry, absorbance, concentration and precision. Theory and methods of air, water, gases, hydrocarbons, pesticides, organic, and inorganic herbicides, biological control of pests, soil and organic sample analyses: types and sources of outdoor and indoor air pollution, introductory treatment of analysis of air pollution, types, effects and sources of water pollution, introductory treatment of analysis of water pollution, types and uses of pesticides, introductory analysis of pesticides, alternative methods  of insect control, integrated pest management, introductory treatment of soil and organic sample analysis. UNIT-8: Course Meteorology: meteorological fundamentals, pressure, temperature, wind, humidity, radiation, atmospheric stability, adiabatic diagrams turbulence and diffusion scales of meteorology. Applications of micrometeorology to vegetate surfaces, urban areas, human beings, animals, Application of meteorological principles to transport and diffusion of pollutants, Scavenging process, Effects of meteorological parameters on pollutants and vice versa .Wind Roses, Topographic effects, Pollution climatology, Seasons in Nepal, Monsoons, El Nino, ENSO, concepts of climate change – global warming, sea level rise, Ozone depletion, green house effect. Elaboration Radiation from the sun and the earth, vertical distribution of temperature and air stability, air pressure and wind with reference to atmospheric circulation, adiabatic diagram and adiabatic lapse rate: dry adiabatic lapse rate, Environmental lapse rate, Saturated adiabatic lapse rate, application of meteorology to vegetated surfaces, application of meteorology to urban areas, application of meteorology to human beings and animals, application of meteorological principles to transport and diffusion of pollutants, effect of meteorogical parameters, discuss turbulence and diffusion processes and illustrate typical wind-rose diagram compiled from wind data to provide some elementary interpretation of wind characteristics, salient feature of pollution climatology, temperature inversion, pollution potential and ventilation coefficient, seasons in Nepal, concept of climate change, greenhouse effect and climate change, global warming and its consequences in future.

Ecology

1.1	Define primary and secondary productivity. What are the methods used for the measurement of primary productivity? Ans: Primary productivity of an ecosystem, community or any part thereof is defined as the rate at which radiant energy is stored by photosynthetic or chemosynthetic activity of producer organisms in the form of organic substances which can be used as food materials. Secondary productivity is the rate of storage at consumer level. Since consumer only utilize food materials already produced, with some respiratory loss and is converted to different tissues by an overall process, gross or net division is not appropriate. Energy flow from producer to herbivores to omnivores and onward is termed as assimilation rather than production. At metabolic equilibrium, photosynthesis equals respiration and this is termed as compensation point There are various methods to measure the primary productivity they as below: (a)	Harvest method: It can be used in situations in which herbivores animals are not important and in which steady state condition is never reached. It is usual in crop fields involving animal species. Since efforts are made to prevent insects and other animals from removing material and the rate of production starts from zero at the time of plantation and reaches maximum at the time of harvest. Weighing the growth produced by cultivated crops and determining the calorific value gives the primary productivity. (b)	Oxygen measurement method: There exists a relationship between oxygen evolved and the food produces during photosynthesis. Dark and light bottles can be used to find productivity. The two sample bottles of same capacity are filled with water drawn from the same depth and left to same depth using stopper. The dark bottle is made light proof in which only respirations occurs but in light bottle both respiration and photosynthesis take place. A sample from same depth is fixed to know the initial oxygen concentration. The suspended bottles are drawn out after 24 hours and change in oxygen concentration are measured using Winkler’s method or by using electronic sensor. (c)	Leaf area index method (LAI): Since leaf is the primary organ in which primary production takes place, its area in relation to ground area is of greater significance. LAI is the total area of leaf per unit area of ground. Mathematically it is expressed as: The rate of production increases with increase in leaf area. LAI up to a certain extent provided other factor especially moisture are not limiting. Generally beyond 4or 5 LAI value, the increase in production values stops or falls depending upon the type of species and prevailing condition. In vertical leaves a high leaf area index is needed to intercept the same amount of light and thus a higher photosynthetic rate is achieved. (d)	Chlorophyll method: chlorophyll content has certainly relationship with primary productivity. In an ecosystem like a desert or an oligotrophic lake the quantity of chlorophyll is low per unit area (ie.m-² ha-1) and hence productivity is also low. Similarly, multi-storied forests in tropics the quantity of chlorophyll is high and also the productivity. If the assimilation ratio and the available light are known gross production can be estimated by extracting pigments and then measuring chlorophyll concentration with the spectrophotometer. The chlorophyll content is related to productivity through suitable equation. (e)	CO2 measurement method (Enclosure method): A large transparent tent or glass box is placed over a plant community. Air is drawn through the enclosure and the CO2 concentration in incoming and outgoing air is measured by absorption of KOH column or by infrared gas analyzer. It is assumed that any decrease in CO2 in incoming air has been used in photosynthesis. If the enclosure is made light, light respiration can be measured. By calculating change in oxygen concentration the productivity can be measured. There are some more methods for measuring the primary productivity they are as given. (f)	Aerodynamic method (g)  pH method  (h)  Bomb calorimetric(I)  Oxygen diurnal curve method  (j)  Extinction of raw materials  (k)  Radio-isotope method. 1.2	What is bio-geo chemical cycle? Describe the nitrogen cycle in the environment. (2055, 2057, 2059, 2062, 2064) Ans: Biogeochemical cycle is the circulation of essential elements of protoplasm from non living environment to living organisms. The movement of mineral is accomplished by the operation of different chemical cycle that keeps on passing the minerals back and forth between organisms and their environment. Because the flow involves biological, geological, chemical nature of process these cycles are called biogeochemical cycles. Nitrogen cycle is the most complex of the earth’s biogeochemical cycles. Although nitrogen present in atmosphere is 78% it can’t be directly utilized by organisms. The first step in nitrogen cycle involves nitrogen fixation in which the gaseous nitrogen is converted into nitrogenous compounds by physiochemical and biological process. The lightening atmospheric reactions are physiochemical and the bacteria (Symbiotic Rhizobium and free living like Azobacter) fix atmospheric nitrogen biochemically to form ammonia N2+ H2                    NH2 Ammonia reacting with water is converted into ammonium ions and which are absorbed by plants in the form of nitrites as nutrients. The conversion of ammonia and other nitrogen compounds into nitrates is called nitrification. During assimilation plants absorb ammonia, ammonium and nitrates which are incorporated in organic molecules like DNA, amino acids and proteins. The animal acquires nitrogen compounds by eating plants (producers) and by plant eating herbivores. Specialized decomposer bacteria and convert the nitrogen rich organic compounds, wastes, dead-bodies of organisms into simpler nitrogen containing inorganic compounds such as ammonia and water soluble salts containing ammonium ions (NH4+). This is ammonification. In a process called denitrification the ammonium ion NH4+ and mainly NH3+ is converted into nitrogen oxide (NO-), Nitrous oxide (N2O) and ultimately N2. The denitrification productgets way into atmosphere and they can begin the same cycle.

1.1	Describe the important vegetations found in different climate zones of Nepal.(2056) Ans: The vegetation of Nepal has been divided by many workers into various phyto- geographic divisions. Stainton (1972) described the vegetation of Nepal under six divisions and thirty five of forest types on the basis of levels of altitude and gradients in climatic parameters. For convenience the vegetation zones can be described as follows: 1)	Tropical zone: This zone includes Terai, Bhabhar and dun valleys. It extends east to west up to 1000 m. and major vegetation types are Sal forest (Shorea Robusta), tropical deciduous river basin forest and tropical evergreen forest. It is represented by humid and warm climate region. Dalbergia sissoo (Sissau), Acacia catechu (Khair), Shorea robusta (Sal). 2) Sub-tropical zone: This zone extends to an elevation up to Mahabharata range, chilaune (Schima wallichi), Katus (Castanopsis indica), Pinus roxburghii and Alnus nepalensis are important vegetation type. Schima wallichi, Castanopsis indica (1000- 1700)m. on the north and south facing slopes, pine forest upto 2000 m and Alnus species upto 2700m occur in Nepal. 3) Temperate zone: This zone runs almost southern side of Himalaya range up to 3000 m and characterized by three distinct types of forests. a) Lower temperate broad leaved forests confineed on north and south facing slopes upto 2200m., prominent vegetation type on Arun valleys and Tamur valley in east Nepal,. Annapurna and Himalchuli on central Nepal, mostly with blue pine and oak forest. b) Temperate mixed evergreen forest confines up to 2700 m are Quercus glauca, Quercus lamellosa, Quercus semicarpifollium, Cedrus deodera dominant in Humla, Jumla on southern slopes with ground orchids. c) Upper temperate mixed broad leaved forest mainly composed of deciduous trees upto 3000m in north and west facing slopes. It includes Juglans regia, Murus serrata associated species are rhododendrons (Rohodendron arboreum, R. falconi, R. barbatum) and Acer species as major vegetation. 4) Subalpine zone: This zone covers the part of Himalaya’s upto 4000m.characterized by silver fir and birch- rhododendron forests. Langtang region Acer species scattered stands of Querocus semicaspifolia, Betula utilis upto 3800m. and constant association of Juniper-Rhododendron species (R. barbatum, R. folconeri, R.  hadgsonli), Juniperus recurva etc. 5) Alpine zone: The zone above 4100m. Compose the association of Juniper Rhododendron, Caragana–lonicera and other alpine meadows in the region of inner valleys.Juniper species like J. recurva indica, J. cummunis and rhododendron species (R. anthopogon, R. lepidotum) are scattered on slopes. The area has several herbs that are commercially important.Beyond this zone no vegetation except some Lichens, mosses scattered. Calculate the Shannon–Weiner diversity index for the following two ecosystem: (2056) Hemlock		210		16 White pine		20		134 Beech			38		7 Red Maple		27		42 Chestnut		22		535 White Oak		5		418 Yellow Bitch		396		4 Black Cherry		12		6 Red Oak		7		30

How do you conclude about the species diversity of these two ecosystems? Ans: The species diversity of ecosystem is calculated by using the Shannon-Weiner diversity index. Mathematically, Shannon-Weiner diversity index (H) is expressed as Calculation of Shannon-Weiner diversity index (H) ofEcosystem A

Calculation of Shannon-Weiner diversity index (H) of Ecosystem B

Therefore, Shannon–Weiner diversity index (H) of the ecosystem A and ecosystem B were found to be 0.53 and 0.5720 respectively. It indicates that ecosystem B has more diversity than ecosystem B. In other word, the tree diversity in ecosystem B is more heterogeneous than in ecosystem A. 1.1	Define adaptation. Discuss the adaptation of living organisms with reference to physical factors. (2057) Ans: The biological phenomenon of fitness of the organism in a particular environment or mode of life is known as adaptation. 1.	Temperature: - it is one of the most important environmental factors & is the limiting one. it affects all the organisms of the vital activities. The organisms are found more active at optimum range of temperature .temperature affects the growth & development. Effect of temperature: Some of the important effect of temperature on living organisms is as follows. •In growth & Development:-optimum range of temperature is required for normal growth & development of the organisms. •In metabolism:-it affects metabolism in the organisms by activating the enzymes. •In reproduction:-it affects the sex ratio in some organisms. •On animal behavior:-optimum temp. is required for normal activities of the organisms. 2.Light:- light energy coming from the sun is a very important factor and is the basic requirement for the existence of life on the earth. Effects of light on organisms:- •On cells:-the ultraviolet rays of light have mutational effect of the DNA of the chromosomes of the cells. •On metabolism:-it affects metabolism indirectly .it produces temperature which activities enzymes which brings about metabolism. •On color:-it has also the great chemical effect on the formation of pigment which produces color of the body. •On locomotion: - it carries locomotion in lower organisms. 3.Moisture: - The organisms survive on land always at certain optimal humidity range .Below and above the range; the activity of the animals diminishes. 4.Wind: - wind of air currents has been considered as an ecological force for the movement and migration of many types of organisms (insects, birds) their bringing the change in the biotic community. 5.Pressure: - Atmospheric pressure on the land changes from place to place .the organisms living on low altitude feel suffocation on high altitude .it affects certain behavior and metabolism of the organisms. 1.2	Explain ecosystem energetic. Describe Y shaped energy flow model in the ecosystem.(2057) Ans: The energy used for all plant life process is derived from solar radiation i.e. about 1/10th million of the total solar radiation reaches the earth’s atmosphere. Solar radiation travels through the space in the form of waves, wavelength ranges from 300mµ - 10µ and above1cm (radio waves) enter the earth outer atmosphere (which is about 1.8 miles or 28 Km. altitude). The energy reaches the earth surface consists largely of visible light and infrared components. On a clear day, the radiation reaching the earth surface is about 10% UV, 45% visible and 45% infrared radiation. About 34% of sunlight reaching the earth’s atmosphere is reflected back into its atmosphere, 10% is held by ozone layer, water vapor and other atmospheric gases. The rest 56% reaches the earth surface. Only a fraction of this energy reaching the earth surface is used by green plants by photosynthesis and the rest is absorbed as heat by ground vegetation or water. In fact only about 0.02% of the sunlight reaching the atmosphere is used in photosynthesis. It is small fraction on which all the organism of the ecosystem depend. The energy component of energy environment thermal radiation comes from any surface or object i.e. at a temperature above absolute zero. This includes not only soil, water and vegetation but also clouds, which contribute a substantial amount of heat of energy radiated downward into ecosystem. In this way in ecosystem energetic we study -: 1)	Quantity of solar energy reaching an ecosystem. 2)	Quantity of solar energy used by green plants for photosynthesis. and 3)	Quantity of path of energy flow from producer to consumer.

Fig Y- shaped energy flow model In y – shaped energy flow model, 2 types of food chain are showed in separate arc, one arm representing grazing and other arm shows detritions food chain. The y – shaped model indicates that food chains are infact under natural condition not completely isolated from one another. For instance dead bodies of small animals that were once parts of grazing food chain become incorporated in detritions food chain as do the faces of grazing consumption of living plants and ultimate utilization of dead organic matter. In practice, under natural conditions the organisms are interrelated in a way that several food chains are complexity of food chain depends on length of food chains. Thus in nature they operate multi channel energy flow. 1.7	Describe the role of positive and negative interactions in the natural biotic community.(2059) Ans: The organisms interact in the environment in different ways with one another. These interactions are important to sustain the animals and plants in the environment. Through the interactions in the natural conditions the organisms evolve. The adaptations and homeostasis develop in the living organisms and communities develop through the means of interactions ranging from population regulation, reproductive success to speciation. This is the interaction between different components of environment (living) that shapes the activities of organisms and feedback mechanism. 1.	Neutralism: Neutralism has not interaction between two populations. It cannot take place in the organisms having same or overlapping function. It is likely to occur in the populations which are functionally differing from each other. It may occur or may take place in marine habitat or oligotrophic lakes. 2.	Commensalism: In this situation one population benefits while other remains unaffected. It generally occurs when one population on its normal growth and metabolism changes the environment or system which becomes favorable to other population. The facultative aerobic microorganism use oxygen and create favorable environment for anaerobic (obligatory) microorganism. The obligate aerobe benefits from facultative anaerobes but aerobic microorganism arealso not badly affected. Some fungi produce extra cellular fungi which decompose cellulose materials and produce glucose from which other microbes may get benefited. 3.	Proto-cooperation (synotrophism): It is the relationship between two populations in which both are benefited but it is not obligatory relationship. Here two populations supply each others requirements. Synotrophism is the relationship between two populations in which the populations are capable to synthesize the materials which can’t be synthesized alone. Usually thousands of pathogens are required to cause disease as a single pathogen is rarely become host defense. 4.	Mutualism: In mutualism there is an intimate or obligate relationship between two populations. Lichens are good examples in which fungus and algal species are mutually associated for complete metabolism. The algal thalli perform photosynthesis while fungal part absorbs the water and other nutrients. 5.	Ammensalism: It is a kind of negative interaction in which one population harms the other but in turn remain unaffected. When a population stabilizes itself in environment it prevents attack of other species e.g. E.coli can’t grow in rumen because of presence of volatile fatty acids produced by heterotrophic population. Acid produced by microbial population in vaginal tract are responsible for preventing from infection of pathogens such as Candida albicans. 6.	Predation: It is one of the negative interaction in which one population is prey and other is predator e.g. the ciliates, flagellates and amoeboid population prey upon bacterial population. This relationship is responsible for the maintenance of bacterial population in balance in soil and aquatic systems. 7.	Exploitation: Here one species harms the other by making its direct or indirect use for support shelter or food. The exploitation may be in respect of shelter or food. The various relationships may be parasitism or predation. Parasite is the organism which lives on the body of another organisms and feeds on the animal and live in its body but do not kill but in the case of predation the animal is killed for food. 8.	Competition: competition occurs when an individual organism tries to obtain a resource i.e. inadequate to support all the individuals harm one another in trying to obtain it. In competition species of same population may involve as well as interacting population of different species. Competition is made for raw material such as light, inorganic nutrients, water, space to grow nest, hide from predator etc. 1.8 What is ecological succession? Describe different process of community succession and regulation. (2060) Ans: Ecological succession can be defined as the natural process by which the same locality becomes successively colonized by different groups or communities of plants. It is an orderly process of community development that involves change in species structure and community process with time. It is directional and therefore predictable. It results from modification of the physical environment by a community i.e. succession is community controlled even though the physical environment determines the rate of change and often sets limit as to how far development can go. The whole processes of primary autotrophic succession occur in a number of sequential steps which flow one another. These steps are as follows. 1) Nudation: This is the development to a bare area without any form of life. The area may develop due to topographic or climatic or biotic factors. a)  Topographic factors: Due to soil erosion by gravity water or wind, the existing community may disappear, other cause such as land slide, deposition of sand, volcanic activity may also be responsible for development of bare area. b)  Climatic factors: Fire, storm, glaciers dry period etc may also destroy the community. c)   Biotic factor: Man is mostly responsible for destruction of forest grassland or any other parts with vegetation. 2) Invasion: This is the successful establishment of species in a bare area. Species actually reaches this new site from any otherarea. This process completes in following process: a) Migration or dispersal: The seeds, spores, or other means of prop gules of the species reach the bare area by any agent like air, water etc. b)  Ecesis or establishment: After reaching to new area, the process of successful establishment of the species occurs as a result of adjustment with the existing conditions. This is known as ecesion. Most of the species reproduce and grow in that condition but only few of them can survive and the servable established. c)  After ecesis as a result of the reproduction, the individuals of the species increase in number and they come close to each other. This process is known as aggregation. 3) Competition and coactions: After aggression of large number of individuals of species at the limited place there develops competition (inter specific and intra specific) for space and nutrition. Individuals of a species affect each others life in many ways and this is called coactions. The species if unable to complete with other species would be discarded. 4) Reaction: This is the most important stage of succession. The mechanism of the modification of the environment through the influence of living organisms on it is called as reaction. As a result of reaction changes takes place in soil, light condition, water, temperature etc.due to the changes in the environment, the environment becomes unsuitable for the existing community. The whole sequences of communities that replace one another community. The whole sequence of communities that replaces one another the given area is called a sere. 5) Stabilization: Finally there occurs a stage in the process when the final terminal community becomes more or less stabilized for a longer period of time and it can maintain itself in equilibrium with the climate of an area. This final community is known as climax community and the stage is called climax stage. 1.9	Discuss the impacts of human activities on ecosystems and their implications. (2058) Ans: Human lives in a very crowded planet. We share the earth with a large number of other species. Human feeding directly or indirectly has been responsible for centuries of accumulated damage to the environment. Whole landscape has been transformed by the axe and plough and much wildlife have been hunted out of existence. Thousands of species are now endangered due to human activities. Human being is also responsible for polluting the environment with chemicals. Some are deadly poisonous. Many other human activities also have threatened the balance of nature. As a result, wild life habitats around the world are now at risk. Human being has great apatite for animal protein. The wildlife is steadily being eaten to extinction. The whole oceans are under similar threat due to over fishing and accumulation of large amounts of pollutants. Thus creating a gap in a natural food chains that can affect other species. Today, some of the world’s most familiar animal species stand at the edge of extinction. Large animals are especially at risk from the habitat destruction. Much extinction has been caused by human introduced animal predators. The desertification is a common phenomenon in many parts of the world due to human activities directly as well as coupled with the natural conditions. Extensive cultivation of agricultural land has resulted in decreased production in many parts of the world due to water logging and salinization. The arctic tundra is a fragile environment that can be easily damage by human action such as mining and other development activities. Slow rate of decomposition, shallow soil, short growing season and slow plant growth rate makes this biome especially vulnerable to disruption. So vegetation destroyed by human activities takes decades to grow back. Tropical forests, the big storehouse of biodiversity, are also being cleared for timber, grazing land and agriculture and eventually leading to desertification and biodiversity loss. 1.10	Define biogeochemical cycle. Describe the carbon cycle and its significance in the environment. (2058,2059,2063) Ans: Biogeochemical cycle is the circulation of essential elements of protoplasm from non living environment to living organisms. The movement of mineral is accomplished by the operation of different chemical cycle that keeps on passing the minerals back and forthbetween organisms and their environment. Because the flow involves biological, geological, chemical nature of process these cycles are called biogeochemical cycles. Carbon cycle: carbon is basic unit of all organic compounds. The source of nearly all carbon found on the living organisms CO2 which is found in Free State in atmosphere and in dissolved state in the water on the earth. In this way the carbon cycle is concern with the atmospheric CO2 incorporation into organic matter by photosynthesis and its subsequent released by the respiration of all living organisms. Carbon constituent is about 49% of dry wet of organisms. Carbon is found in three major forms in nature ie. CO2, carbon molecule and carbonate in the earth crust. Carbon cycle is small but very active. Carbon cycles rapidly between the atmosphere and hydrosphere and living organisms. Carbon cycle is also important for climate and weather. Atmospheric CO2 dissolve with rain water in the form of acids reach to the soil. Green plants get their carbon by absorbing from the soil. Carnivores feed on plants, omnivorous feeds on carnivores. Here the carbon is cycling from one level to other and when they die the carbon reach to the atmosphere and in soil in different process. Carbon is released to the atmosphere directly as CO2 during the respiration of plants and animals, when they are burned then CO2 is again released into atmosphere. Bacteria and fungi attack the dead remains of plants and animals. They degrade the complex carbon compounds into simple carbon which are then available for other cycles. Some organic carbon become incorporated in to the earth crust as coal, gas petroleum and are deposited which release after long period of time.

1.7	Define biodiversity and explain the importance of biodiversity.(2063) Ans: Biodiversity is the variability among living organisms and their habitat. In other words; biodiversity means the richness and variety of living beings in the world as a whole or in any location with in it. The biodiversity was defined by convention on biological diversity (CBD), 1992 as the variability among living organisms from all sources including inter-alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems. It encompasses the total number, Varity and variability of life forms and combination existing within the living world. It includes diversity within species between species and ecosystem. Biodiversity consists of three fundamental categories, they are:-       a) Ecosystem Diversity.	b) Species Diversity. c) Genetic Diversity. Ecosystem Diversity: An ecosystem comprises a dynamic complex of plant, animal and micro-organism communities and their non living environment which which interact as a functional unit. Ecosystem can be small or large. Ecosystem diversity refers to the variety of forest, grassland, wetland, aquatic ecosystem and other biological communities. Species Diversity: Species are the population of organisms where members are often to interbreed freely on the natural condition. Species diversity is the variety of species on earth and in different habitats of the planet. The total number of species in the global has been estimate to range from 5-30 million out of which 0.5 million are flora and 1.7 million species are fauna. Measures of species richness are the basis for the observation. The diversity increases with decreasing latitude on earth in general. Genetic Diversity: Genetic diversity refers to the variations of genes within living   organisms i.e. the genetic differences among population of a single species and among individuals within a population of a single species and among individuals within a population. E.g. For thousands of traditional rice varieties of Nepal. The importance of biodiversity can be outlined as follows. 1)	Various uses of plant diversity: Plant diversity provides various services and goods such as food, timber,      ornamentals, oil fuel etc. a)	Food plants: Out of 250,000 higher plant species, 3000 species are known to have food values. Among them paddy, wheat and maize provides 75% food to world. b)	Timbers plants: Timber is most common good provided by plants. Some of timber species are Sal, Sissoo, Simal that are found in tropical region. c)	Rattans: Rattans are used for making furniture baskets, ropes etc. d)	Medicinal plants: WHO has listed over 21,000 species having medicinal use around the world. Most of the medicinal plants are harvested from wild and very few are cultivated. e)	Ornamental plants: Many species are used as ornamental plants some of the species are Orchids, Marigold, Chrysanthemum, Gurans etc. f)	Fuel wood: Almost many species of shrubs and trees are used as firewood e.g. Sal, Salla, Katus, and Jammu etc. 2)	Various uses of animal biodiversity: a)	As food: Some domestic animals and poultry animals and some aquatic animals are used as food e.g. Goat, sheep, hen, fishes etc. Some wild species of animals are also used as food. b)	Some species of wild and other animals are kept for pleasure as pet e.g. Cat, dog, peacock, parrot etc. c)	Some animals are kept to get wool and other raw materials e.g. Sheep are kept for wool, rabbit for their fur, silkworm for silk thread etc. d)	Animals help for pollination and also are kept for traditionalvalues. 1.8 1.9 1.14	   2.1 Ectones and edge effect in ecology. (2055) Ans: Ecotone:-Zone of transition between two or more diverse communities is called as an ecotone. For example, between forest & grassland also known as junction zone. Overlapping of species occurs, therefore more species than in the communities flunking it. The higher density means higher species richness in the ecotone. Edge effect in ecology:-The effect extended by adjoining communities on the population structure within the marginal zone (ecotone) which often consist of greater number of species and higher population densities of some species than either adjoining community created by forest fragmentation.Studies have shown that such effect are brought by differences in microclimate and vegetation composition. Microclimate: 1) Photosynthetically active 2) Air temperature 3) Vapor pressure Vegetation composition:- 1.  Overall density and basal area for mature individual are higher at the forest edge than in the forest interior 2.   High probabilities of tree mortality by wind throw. 2.2   Discuss the ecological principles associated with species diversity concept. (2060) Ans: The ecological principles are: a)   If there is high species diversity it is biologically controlled ecosystem and if there is low species diversity in physically controlled ecosystem. b)  Species diversity increases with decrease in the ratio of ant thermal maintenance to biomass (R/B ratio). c)   Species diversity is an indicator of stability of the ecosystem. Stable community has higher specific density. d)  If there is high species diversity longer food chain and more interaction is found. e)   If there is high species diversity are found in older communities and low species diversity is found in newly existed area. f)  Species diversity is much influence by the functional relationship between the trophic levels. Species diversity decline when habitat removal (over grazing) acts as a stress and reduce the species diversity and removal of species decreases diversity. 2.3	 Describe the ecological niche. (2060) Ans: The ecological niche includes not only the physical space occupied by an organism but also its functional role in the community and its position in environmental gradient of temperature, moisture in soil and in other conditions (Odum 1956). It includes three aspects spatial or habitat niche, tropical niche and multidimensional or hyper-volume niche. The habitat often organism or population includes other organisms as well as the abiotic environment etc. E.g. Notonecta: Literal zone of ponds and lakes with vegetation, Trifolium plants: Deciduous forest under the shaded condition, Sand sage grass community: Sandy soil along the north side of the river in the southern great plains of USA. Mainly abiotic factor. (Miller 2002) a species niche involves everything that effects the survival and reproduction. It involves: a)  The range of tolerance for various physical and chemical conditions. b)   The types and amounts of resources it uses such as food, nutrients and space. c)  How it interact with other living and non living components of the ecosystems in which it is found. d)   The role it plays in the flow of energy and cycling of matter. There are different types of niches they are: a)  Fundamental niche: It is the full potential range of physical, chemical and biological condition and resources an organism theoretically use if there were no direct competition from other species. b)   Realized niche: To survive and avoid competition for the same resources, a species usually occupy only part of the fundamental niche in a particular community or ecosystem which ecologist says it realized niche. c)  Specialized niche: Narrow niches, only one kind of habitat only a new range of climate condition and other environmental factors use only one as a few type of food. Important to understand ecological niches are: 1)   Ecological niches help in preventing the species from premature extinction. 2)  Ecological niches can be useful to asses the environmental change. E.g. Deforestation, Ploughing up a grassland, polluting the lakes and river etc. will change the niche of species. 2.4   Ammensalism and commensalisms (2055, 2059) Ans: Ammensalism: It is a kind of negative interaction in which one population is inhibited and the other is not affected. It is just temporary interaction. Micro organism that produces substance toxic to competing population will naturally have competitive advantages once an organism establishes itself within a habitat, it may prevent other population from surviving in the habitat e.g. E.coli cannot grow alone in rumen because of presence of volatile fatty acids produced by heterotrophic microbial population. Acid produced by microbial population in vaginal tract are responsible for preventing from infection of pathogens such as Canadidaalbicans. Commensalisms: It is the type of positive interaction in which association between members of different species only one is benefited and other is not affected or neither is harmed. Here two or more population lives together without entering into any kind of physiological exchange. Some examples are: a) Lianas: These are rooted vascular plants growing out on the bark and branches of trees. They maintain erectness by getting the mechanical support of trees so that they can get better light conditions. They are common in dense forests of moist tropical climates. They have no direct nutritional relation with the substratum trees. b) Epiphytes and Epizoans: Epiphytes are plants growing perched on other plants. They use other plants as support and not for water or food supply. They differ from lianas that epiphytes are not rooted in soil. Epiphytes may grow either in trunk or leaves. They are most common in tropical rain forests. Many orchids; in epiphytes there is a large vitamin over the rooted surface which are whitish in color and can take abundant water from the atmosphere. Some plants on the surface of animals e.g. green algae grow in the long grooved hairs of sloth like wise Basaciladae on the back of fresh water turtle. 2.5	Describe the characteristics of grassland ecosystem and forest ecosystems. (2058) Ans: The characteristics of grassland ecosystem are as below: 1)  Grassland ecosystems are characterized by dominance of herbs particularly the grasses. 2)   Stratification does not occur in grassland ecosystem due to dominance of herbs. 3)  Grasslands are characterized by low rainfall and high evapo-transpiration. 4)   Soil remains dry most of the time (in dry season). The characteristics of forest ecosystem are as below: 1)  Forest ecosystem are characterized by the dominance of tall trees, large canopy coverage and stratification like crown level, sub- crown level and ground level vegetation. 2)   Climbers are significant in forest ecosystems. 3)  Represent sufficient quantity of rainfall. 4)   The soil remains moist through the time. 2.6 Highlight the major environmental policies of Nepal. (2061) Ans: Policies are formulated and implemented for the betterment of certain area or sector. Environmental policies are formulated for conservation and to sustain the environment. There are different environmental policies in Nepal which are formulated in different periodic plan of Nepal and in Nepal environmental policies and action plan (NEPAP). Not only this, government of Nepal signed different convention agreements and treaties related to environment. Thus as a party, Nepal should implement different policies related to environment in these policies of Nepal. The environmental policies and action plan is a part of government efforts to the environment concern into country development process. (NEPAP) has five main aims of government policies these are: 1)	To manage efficiently and sustainable and natural resources. 2)	To balance development efforts and environmental conservation for sustainable fulfillment of the basic needs of people. 3)	To safeguard national heritage. 4)	To mitigate the environmental impacts of development projects and human action. 5)	To integrate environment and development through appropriate institution, adequate legislation and economic incentives and sufficient public resources. The NEPAP is organized around these five policy objectives. 2.7  Causes and consequence of forest degradation. (2055, 2062) Ans: population explosion both in humans & livestock increases the demand for more food & natural resources from forest. Increase in population led to the demand for more cropland that brings cutting of forest. 1.	Increase demand for timber and fuel wood has made many places barren. 2.	Overgrazing by animal leave the pasture vulnerable to soil erosion deforestation. 3.	Large scale felling is done for more demand by industry for wood, paper etc. 4.	Construction of roads, dams, urbanization, more land for agriculture or mining all leads to deforestation. Consequences of forest degradation         It leads to soil erosion and brings a series of unfavorable changes in the whole biosphere .this leads to loss of precious life & loss of many species affecting the status of biodiversity to which man had mot given a thought so far. In Nepalese context this process at presence preceding on at a rate of about 100 thousand hectare per year .if this rate continues, our country may be entirely deforested in 25 to 30 years. I.	loss of biodiversity II. loss of habitat for wild life species III. desertification IV. climatic effects V.	unbalanced ecosystem VI. landslides VII. Other too many crises for human & other species. 2.8	What happens to the matter in an ecosystem as a result of the law of conservation of matter? (2056) Ans: According to law of conservation of matter, we can say that matter can neither be created nor destroyed but can be transfer from one thing to other, one organism to other .likewise in an ecosystem, there are different organism some are producer, some consumer &some decomposer .the matter present in the soil is taken by the producer and the consumer takes their food from producer .at that time the matter present in the producer goes to the consumer. According to tenth law only 10 % of the matter is consumed by the consumer and rest 90 % remain wasted, the waste matter is then decomposed by decomposer & the matter again reach to the soil .in this way we can explain that matter is not wasted it is transmitted from one organism or substance to other but do not destroy .so in conclusion, we can say that in an ecosystem matter is transferred not destroyed. 2.9	Explain the practical significance of ecology to the human society. (2056) Ans: Ecology is the science that needs minimum time & labor for its introduction to a lay on. Present day problems of varied nature in human life are directly or indirectly very much related to ecology, as their solution needs an ecological knowledge. These day’s ecology has been contributing very much to socio-economic, political & other similar policies of the world. There are interdependency not only between ecology & other areas of plant sciences but also between ecology and physical as well as social sciences. Ecology indeed plays an important role in human welfare .This is primarily a field subject and modern ecology is concerned with the functional interdependences between living and their environment. Ecology plays an important role in agriculture (crop rotation, weed control etc, management of grasslands (range management), forestry ,biological surveys ,pest control, fishery biology & in the conservation of soil wildlife. forest, water supplies etc. The international problem of environmental pollution also needs ecological attention. 2.10	Discuss the role of organic herbicides in the environment. (2056) Ans: Organic herbicides plays an important role in the environment .till now organic herbicides are not in common use in our country Nepal but it is popular technologically in developed countries. In Nepal, organic herbicides like Nim, Titepati, Asuro, etc are widelyused in the agricultural practices mostly in the rural areas where the chemicals are less available. The soil microbes and other related organisms are not disturbed by these herbicides. The impacts of these herbicides in human are very insignificant compared to the synthetic and chemical herbicides like DDT. Thus, organic herbicides no to very low side effects in the soil because these can easily be decompose by the decomposers so that the ecosystems are not disturbed. The acidity or basicity of soil may increase due to chemical herbicides but organic herbicides do not have much chemical effects on the soil pollution. So that organic herbicides are most useful in the environment. 2.11	Describe ecological pyramids of forest and grassland ecosystem. (2057) Ans: Pyramids of number:-actually the pyramids of number do not give actual picture of food chain as they aren’t very functional. They do not indicate the relative effect of the geometry .food chain & size factors of the organisms. They generally vary with different communities with different types of food chain in the same environment .it becomes sometimes very difficult to represent the whole community on the same numerical scale. (As in forest ecosystem)

Tert.consumer Sec.consumer Herbivores Producer

Grassland ecosystem

Fish nettles Small fish planktons big fish

Aquatic ecosystem

Lion Snake & lizards Elephant & bird Tree

Predator food chain Tree Birds Bugs hyper parasite, mice & bugs

Tert.consumer

Sec consumer

Primary consumer

Producer

Parasitic food chain

1	Pyramid of biomass:-they are comparatively more fundamental, as they instead of geometric factor, show qualitative relationships of the standing crops .these pyramid of biomass in different types of ecosystem are shown .in grass –land and forests, there is generally a decrease in biomass of organism at successive levels from the producers to the carnivores. The pyramids are upright .however in pond, the producers are small organisms, their biomass is least and this value gradually shows an increase towards the apex of the pyramid, thus made the pyramids inverted.

Hawk Rabbit Grass

Grass land ecosystem

Producers Herbivores carnivores

Aquatic ecosystem

Tiger, Snakes Elephant ,cow Trees Forest ecosystem

2	pyramid of energy :- of the three types of ecological pyramids ,the pyramids of energy give the best picture of overall nature of the ecosystem .here, number & wt.of organisms at any level depends not an amount of fixed energy any one time in the level just below but rather on the rate at which food is being produced. the pyramid of energy is a picture of the rates of passage of food mass through the food chain .in shape it is always a gradual decrease in the energy content at successive tropics levels from the producer to various consumers. The species structure includes not only the number and kinds of species but also diversity of species i.e. the relation between species no. and individuals or biomass and the dispersion /spatial arrangement of individual of each species present in the community.

Tert.consumer Sec.consumer Primary consumer Producer

Pyramid of energy

2.12	Describe the role of ecotype in biological diversity. (2059) Ans: Ecotypes may be also called as ecological or physiological races. According to Thomson, an ecotype is the product arising as a particular habitat. The plants in this case are genetically distinct but are put into same taxonomic species. The different ecotypes of a particular species may differ in the edaphic,biotic or microclimatic requirements. Thus, in ecotypes, adaptations become irreversible or genetically fixed variations. These arise only by irreversible change of genes through hybridization or irregularities during mitosis or meiosis by chance. The development of ecads and ecotypes in one species shows this capacity of distributions to wider areas. By developing such distinct population, the species adapt itself to the changing new types of conditions. The response to the changing environment by the species are met with the development of variations that may be temporary i.e. environmentally based (ecads) or genetically fixed (ecotypes). The ecotype development, in a way, can be viewed as the increase in the local-biodiversity. And this depends on the degree of plasticity possessed by the corresponding species. 2.13	Discuss the ecological indicators to assess the quality of environment. (2059) Ans: The term indicator organism refers to plants, animals or microbes which are indicators of ecological conditions. By their presence or absence of specific characteristics they give clues to various ecological conditions. The species and morphology of plants growing in certain areas can provide valuable clues about the occurrence of the minerals and metal bearing deposits beneath the surface. E.g. in USA plants of genus Astragalus grow in association with selenium. Organisms with relatively narrow tolerance level to specific environmental factors make the best indicator organisms. The narrow the tolerance the greater the accuracy in indicating specific conditions. If an aquatic organisms grows only in a pH from 8 to 9, its presence would be an accurate field indicator of alkalinity. Different indicator can define the type of environment they belongs to. In aquatic ecosystem if there is Utricularia charawolfia, then water is polluted. Presence of Fusilinds (protozoan) in the soil indicates the petroleum deposits. Blue green algae in water indicate serious water pollution. Similarly the presence of E. coli represents the water pollution from sewage. This shows that ecological indicators have important aspects to assess the quality of environment. 2.14	Describe the ecological dominance with its ecological significance. (2058) Ans: Communities have producer, macro consumer and micro consumer, within these groups species which largely control the energy flow and strongly affect the environment of all other species are known as ecological dominance. Not all organisms in a community are equally important in determining the nature and the function of whole community of the hundreds or thousands of kinds of organism that might be present in a community, a relatively few species or species groups generally exerts the major controlling influence by their number, size, production and other activities. The degree to which the dominance is concentrated in one several or many species can be expressed by an appropriate index on dominance that sum of each species importance in relation as a whole. Suppose, we list a species with their number, Eg: Trifolium – 28, Cynodon – 10, Insects – 20, frogs – 2. From this it would be clear that Trifolium is the dominant among producer, and insects among consumers. Here removal of dominant would result in important changes not only in the biotic community but also in a physical environment; where as removal of a long dominant species would produce much less change. Generally dominants are those species in their tropic group which have the largest productivity. 2.15 Describe phosphorous cycle and its significance. (2061) Ans: Plants and animals obtain phosphorus which occurs in the soil as different forms and phosphate. Phosphorus is a component of nucleic acid, ATP, ADP, NADP etc. Phosphorus occurs in soil in various forms and entry of phosphorus in the green plants occurs both from organic and inorganic pool. (Fig. Phosphorus cycle) The dissolved phosphate is absorbed by plants and converted to organic form. From plants, it travels to various tropics levels in the form of organic phosphates. When plants and animals die, the decomposers attack them and liberate phosphorus to the environment. The bones and teeth of animals is composed of good proportion of phosphorus is lost to the deep sediments. The volcanic apatite process also gives the phosphate which by erosion remains as dissolved phosphate. In this way, both physical and biological process occurs during the phosphorus cycle. Phosphorus cycle includesmainly two steps: 1)  Conversion of organic phosphates into insoluble inorganic phosphates: Many soil microorganisms produce enjymes (Phosphatases) that decomposes different organic phosphorus compounds (Nucleo proteins and leciltenis) in the soil. In this decomposition organic phosphorus is converted into phosphoric acid, which combines with the soil bases to produce salts of calcium, magnecium and iron. These salts are less soluble and thus less available to plants. 2)   Conversion of insoluble inorganic phosphates into soluble inorganic phosphates: Actually solubility of phosphorus is mobilization by phosphoric acids. The microorganisms produce acid like sulphuric acids and nitric acid which atleast help in mobilizing phosphorus. The action of acid to convert insoluble phosphates into soluble ones is generally called ‘Solublization’. Phosphorus cycle  2.8	What are the major categories of protected areas in Nepal? (2061) Ans: Protected areas are categorized in Nepal by following ways:- 1)	National parks: this is an area, a site for conservation management, utilization of animals, birds, vegetation or the landscape together with the natural environment. i.	here the entry is restricted without permission. ii.	guarded by the army iii.	managed by the department of national parks & wildlife conservation (DNPWC) 2)	Wildlife reserve: - An area  set aside for  conservation and management of animal and bird resources & their habitats. I. guarded by Nepal army II. Mismanaged by DNPWC 3)	Hunting reserves: - this is an area set aside for the management of animal and bird resources for the purpose of sport hunting.   I. guarded by Nepal army and managed by DNPWC 4)  Conservation area: - this is the area managed with an integrated plan for the conservation of the natural environment and the sustainable area of natural resources. Annapurna conservation area is the only one which exists under this category & it an example of managing a protected area without the local community. 5) category Makalu- Barun national parks & conservation area.  I. This includes national park area & a conservation which fulfill the    buffer zone concept.  ii. No presence of army  iii. Manage of DNPWC 2.16  Discuss the consequences of forest degradation.( 2061) Ans: The destruction of forest due to the effect of different factors like biotic, abiotic and climatic factors and results in the loss of biodiversity, important plants, herbs and animals, trees in the forest is called degradation of forest. The forest degradation doesnot imply only to deforestation but also to the quality loss of forest. Some of the major consequences of forest degdration are: 1)   Destruction of biotic potential of land leads to desertification. 2)  As forest is the home of many wild animals, birds and aquatic organisms, the degradation leads to disappearance of many vegetation, wild lives and disbalance the forest ecosystem. 3)   Due to degradation, floods and landslides occur and thus destroy the remaining life and vegetation of the forest. 4)  Inhabitant of that area face acute water scarcity and semi desert conditions due to forest degradation. 5)   Due to degradation, soil erosion takes place which leads to heavy loss. 6)  Agro ecosystem is highly affected due to drought, soil erosion etc. 2.17	 Why Nepal is considered to be rich in biodiversity? (2062) Ans: Biodiversity is the variability among living organisms from all sources. In other words, biodiversity means the richness and variety of living beings in the world as a whole or in any location within it. It includes diversity within species between species and ecosystem. Nepal is geographically divided into three region i.e. Himalayan region, hilly region, and terai region, within each region having different climate and different environment etc. The environment is very much diverse in three different regions. The vegetation found terai belt are not similar to those of hilly and Himalayan region. As whole Nepal is rich in biodiversity with many of the species are found here that are found in the world. In Nepal 466 species of lichens, 1666 species of fungi, 853 species of bryophyte, and 380 species of pteridophytes are found which is in highest amount. Also 27 species of gymnosperm and 6000 species of angiosperm are found which makes the diversity in Nepal. In case of flora 181 species of mammals, 844 species of aves, 100 species of reptiles, 43 species of amphibians, 185 species of fishes, and 5052 species of insects are found. This shows that there are many species found in different parts of the country. In Nepal there are 114 ecosystems and 35 types of forests. Hence, Nepal is considered to be rich in biodiversity. 2.23	Describe the characteristic features of tropical forest ecosystem. (2063) Ans: Forest is a relatively large area of closely canopied trees, forest occupy roughly 40% of the land. But in Nepal forest occupy only 29% of the land, so we can’t say that Nepal is rich in forest ecosystem. In Nepal tropical forest ecosystem consists of northern coniferous forest, temperate deciduous forest, tropical rain forest and Mediterranean surb forest. The following are the characteristics feature of tropical forest ecosystem. a) Vertical structure (Stratification): It is bottom to top spatial configuration of above ground within a forest stand. It generally includes the following strata. Ground stratum-   0-1m consists of herbs and seedlings. Shrub/ under storey stratum-   1-4m shrub and saplings. Sub-canopy-   4-10m trees. Canopy stratum-   above 10m consists trees. Emergent trees-   above 20-25m eg tropical forest. b) Forest edge effect:  the effect exerted by the adjoining community on the population structure within the marginal zone. 	 It has higher light regime. 	It has higher species richness. c)	Forest fragmentation and other disturbances: It is a change in the spatial configuration of forest in which formerly continuous forest areas turned into small strands. This results disruption of continuity. Its effects are. 	 Reduce forest area. 	 Increase isolation. 	 Increase disturbances. 2.24 Discuss the development of ecological niches. (2063) Ans: Ecological niche can be defined as the niche that includes not only the physical space occupied by an organism but also the functional role in the community and its position in environmental gradients. The term ‘Ecological Niche’ was first coined by Joseph Grinnel to refer a stand of  the ultimate distribution  unit within which each each species is held by its structural and instinctive limitations. According to him no two species in the same general teritoty ca occupy for long identically the same ecological niche. Ecological niche refers to three aspects in a space occupied by an organism i.e. 1. Physical space: it is concerned with the physical space occupied by an organism. It includes the habitat of an organism as well as the area frequented by the organism. 2. Fundamental niche or functional role: it is concerned with the trophic position of an organism. It is the full potential range of physical, chemical and biological condition and available resources. Environmental gradients: this refers to the totality of biotic and abiotic factors to which a given species is uniquely adapted. 2.25 Explain the role of light and space in the process of competition.(2060) Ans: Competition is an interaction between species that use the same limited resource and harm one another while seeking a resource. In the other words, Competition occurs when a number of organism of the same or of different species utilize common resource that are in short supply (exploitation); if the resources are not in short supply, competition occurs when the organisms seeking that resource harm one another in the process (inference). The light and space are resource for living organism that are necessary to growth and development of them. The short supply of light and space lead to compete each other (between organisms within species and among species). Their role in the process of competition is briefly discussed below: a) Role of light in the process of competition Light is one of the fundamental resources to the plants or producer and is also required to animal or consumers. The role of light in the process of competition is clearly seen in plants. Plants require light in the process of photosynthesis. All plants try to obtain maximum amount of light for photosynthesis, especially in forest that leads to enhance the competition. Similarly, light also requires for ripening of fruit. To obtain maximum amount of light, plant produces branches, leaves and sometime special types of chemical aggression (allelopathy) that harm and suppress other species. It is commonly observed in forest and grassland ecosystem especially in tropical region. b) Space in the process of competition Space is also considered as a resource. Space is necessary for good growth and development of living organisms. The space becomes a cause of competition if there is limited space for nesting, food searching/ feeding and water. Its role mainly observed in animals and birds. However the competition observed among micro organisms for space as feeding area. The effects of the resources such as light and space in competition were experimentally explained by different models such as Lokta-Voltera model, Tilman’s experiments, Gause’s principle. The competition for space is commonly seen in plant communities where the individual plants compete to acquire the space in different ways. 2.26 2.27	2.28	  2.29	2.30	  2.31	2.32	 2.33   There are different types of niches they are: a) Fundamental niche: It is the full potential range of physical, chemical and biological condition and resources an organism theoretically use if there were no direct competition from other species. b) Realized niche: To survive and avoid competition for the same resources, a species usually occupy only part of the fundamental niche in a particular community or ecosystem which ecologist says it realized niche. c) Specialized niche: Narrow niches, only one kind of habitat only a new range of climate condition and other environmental factors use only one as a few type of food. Important to understand ecological niches are: 1) Ecological niches helps in preventing the species from premature extinction. 2) Ecological niches can be useful to asses the environmental change. E.g. Deforestation, Ploughing up a grass land, polluting the lakes and river etc. will change the niche of species. 2.34 2. 2.36 2.37 3.1 Grassland and wetland ecosystem.(2055) Ans: Grassland ecosystem	wetland ecosystem 1)	Tall grass land (5-8)ft .tall 2)	Mid grassland(2-4)ft tall Short grassland (0.5-1.5)ft tall
 * These are the communities with limited moisture or water content.
 * There are three types of grassland ecosystem i.e.

Bees, wasp etc lies in grassland ecosystems. * The effect of water is all important in determining the type of wetland ecosystem. 1)	Marine wetland ecosystem a)Mangrove swamps b)salt marshes 2)	Flood land ecosystem 3)	Swam & marsh ecosystem 4)	Bog ecosystem
 * Lizards, snake, grasshopper, birds,
 * There are 4 types of wetland ecosystem i.e.
 * Large carnivorous, alligators, crocodile, sea birds, amphibians & reptiles lies in wet land ecosystem.

3.1	Intraspecific and interspecific competition. (2055) Ans: interspecific competition	Intraspecific competition
 * This is the type of competition, the species of different population or taxonomy involves.
 * This competition is responsible for maintaining the species diversity in certain place.
 * It may leads to extinction of certain species.	* This is the type of competition, the species of same population or taxonomy involves.
 * This competition is responsible for leveling of a certain density of a population.
 * It leads to limitation of growth of certain species.

3.2	Primary and secondary succession. (2055) Ans: Primary succession	secondary succession
 * If the community development begins in the area that has not been previously occupied by any community. The process is called primary succession.
 * It tends to begins at a lower level of productivity.	* If the community development is proceeding in an area from which a community was removed, the process is called secondary succession.
 * It tends to begins at a higher level of productivity.

3.3	Autotrophic and Heterotrophic nutrition. (2055) Ans: Autotrophic nutrition	Heterotrophic nutrition
 * Autotrophic organism are those which produce their food themselves by absorbing sunlight, water etc. and the feeding mechanism of these organism is called autotrophic nutrition.
 * In this minerals are obtained direct from nature.	* Heterotrophic nutrition is the nutrition which is the nutrition which is obtained from producer and other.

3.4	Ecotype and ecocline. (2055) Ans: Ecotype	ecocline
 * In these minerals and other compounds is obtained from nature as well producer and organism.
 * These are ecological or physiological races.


 * They are genetically fit.
 * In this species adapt itself to the changing environment.	* These are the outcomes of interaction of community gradient &environment gradient.
 * They are physically fit.
 * These are effected by environment factors.

3.6 Euryhydric and Stenohydric. (2056) 3.1	Euryhydric and Stenohydric. Ans: Euryhydric	Stenohydric
 * Long range for the tolerance of water.
 * It is suitable for aquatic plants.
 * Lotus grows in euryhydric environment.	* Short range of tolerance of water.
 * Suitable for amphibious plants.
 * Maize grows in stenohydric environment.

3.1	Speciation and Extinction. (2063,2064) Ans: Speciation	Extinction
 * Process of formation of new species due to temporal and spatial changes.
 * Increases biodiversity by formation of new species.

Extinction
 * Types: Allopatric and sympatric.
 * Process of eradication (going for ever) due to natural and anthropogenic causes.
 * Decrease biodiversity (species and genetic) through removal of species from an area.
 * Types are global and local.

3.8 Temperate and alpine zone of Nepal. (2063,2064) Ans: Temperate zone	alpine zone Temperate zone of Nepal Alpine zone of Nepal
 * Broad leaved vegetation is found in this zone.
 * The productivity is higher than in other region.
 * Coniferous forest is found in this zone.


 * The productivity is lower than in Temperate zone.

3.9 Trophic niche and spatial niche.(2057) Ans: Tropical niche	spatial niche
 * It is covered with the tropical position of an organism.
 * E.g.:-distribution of seven species of millipedes in forest floor of a maple oak forest	* It is concerned with the physical space occupied by an organism.
 * E.g.:-the occurrence of various species of birds in Galapagos islands in south America.

3.1	Lentic and Lotic environment.(2058, 2063) Ans: Lentic system	Lotic system
 * System is stagnant.	* System is washed frequently.
 * Dissolve oxygen is less.	* Dissolved oxygen is more.
 * Animal in this system is not adapted for high water current.	* Animal in this system is adapted for high water current.

3.2	Consumer and decomposer. (2058) Ans: Consumer	Decomposer
 * They may be higher plants or animal.
 * They take the energy or nutrients from producer.
 * They are physically more developed.	* They are lower or smaller organism.
 * They supply essential nutritional material to producer.
 * They are not physically well developed.

3.12	Nitrification and denitrification. (2055) Nitrification	denitrification Nitrification Denitrification
 * Process of converting ammonia to nitrate and then to nitrite is called is called nitrification.
 * Carried by nitrifying bacteria.
 * Process takes place under aerobic condition.
 * Process of converting nitrates and nitrites into free nitrogen in the atmosphere is called denitrification.
 * Carried by denitrifying bacteria.
 * Process takes place under aerobic condition.

3.13	Mutualism and Co-operation. (2058) Ans: Mutualism	Co-operation
 * The interaction between two species in which both are benefited but the interaction is obligatory is called mutualism.


 * Example: Association between algae and fungi to form lichen. Algae has chlorophyll and prepare food which is taken by fungi, algae can use the mycelium of fungi as a substratum. Neither of two can grow alone.	* The interaction between two species in which both populations are benefited but the relations are not obligatory is called co – operation.
 * Example: Sea anemone being attached to the shell of hermit crab. The sea anemone is carried by crab to fresh feeding sites. The crab in turn is protected from enemy. The relation is not obligatory.

3.14 Renewal and perpetual natural resources. (2058) Renewal natural resources	perpetual natural resources Renewal natural resources
 * The natural resources which can be reused again and again are called renewable natural resource.

Perpetual natural resources
 * These natural resource can be reused.
 * E.g. hydro electricity, minerals etc.
 * Those natural resource which is completely inexhaustible and is totally independent from anything are known as perpetual natural resources.
 * These natural resource are inexhaustible so can make maximum use of it.
 * E.g. sun, air etc.

3.3	Ex-situ and in-situ conservation. (2058) Ans: Ex-situ conservation	In-situ conservation
 * It is also called as on situ preservation.
 * It refers to the preservation of species of plants and animals in their own natural habitat.
 * Such conservation site include national parks, wildlife reserves, conservation areas etc.	* It is also called as off situ preservation.
 * It refers to the preservation of species of plants and animals outside their own natural habitat.
 * Such conservation site include gene banks, zoological, botanical garden, aquarium, seed bank etc.

3.1	Oligotrophic and eutrophic lakes. (2059) Ans: Oligotrophic lakes	Eutrophic lakes
 * These are deep.
 * They have low primary productivity.
 * Litteral plants are scarce and plankton density is low.	* These are shallow.
 * They have high primary productivity.
 * Litteral vegetation is more abundant, plankton populations are denser.

3.1	J-shaped and S-shaped growth forms. (2061) Ans: S-shaped growth Curve	J- shaped growth Curve
 * In this population grow first slowly, then more rapidly and then least slowly; when it is plotted in a graph then S-shaped curve is obtained.
 * This type of growth form is density dependent.
 * Usually this type of growth is found in plant's animals and human being.	* In this type the population firstly does not grow rapidly but after time interval the growth takes place rapidly when it is plotted in a graph then J-shaped curve is obtained.
 * This type of growth curve depends on food supply.
 * Usually this type of growth form is found in algae, annual plants and insects.

3.2	Tropical and temperate zones of Nepal. (2061) Ans: Tropical zones	Temperate zones
 * This zone includes terai, chure bhabhar and dons valleys.
 * The major vegetation types are soil forest.
 * E.g. Dalberia sisso (Sissoo), Acacia catechu (Khair).	* This zone includes southern sides of Himalayan ranges.
 * The major vegetation types are broad leaved forest, evergreen forests.
 * E.g. pine, oak and rhododendron etc.

3.3	Ecad and ecotype. (2061) Ans: Ecad	         Ecotype.
 * These are known as habitat forms or environmentally induced variation.
 * Different ecade of same species are morphologically distinct.
 * If one type of ecade is trans planted in an environment of another type of ecades, its different would change into lateral type.	* These are known as ecological races or physical races.
 * Different ecotype of same species is genetically distinct.
 * If one type of ecotype is trans planted in an environment of another type of ecotype, its different would not change.

3.4	Mutualism and parasitism. (2061) Ans: Mutualism	Parasitism.
 * The interaction between two species in which both species are benefited is called mutualism.
 * E.g. Association between algae and fungi. Algae prepare food and used by fungi and fungi absorbed water which is also used by algae.	* The interaction between two species in which one species is benefited and other is affected is called parasitism.
 * Leach sucks the blood of animal but the animal is totally harmed.

3.1	Herbicides and insecticides. Ans: Herbicides	insecticides
 * These are the chemicals used to in an effort to inhibit or destroy undesirable life forms (only green weeds and plants) which are considered as nuisance.
 * They inhibit the growth of limited group or unwanted herbs.	* These are the chemicals used to in an effort to inhibit or destroy undesirable life forms (insects).

3.2	Gross primary productivity and net primary productivity. (2062) Ans: Gross primary productivity	Net primary productivity
 * They inhibit the growth of insect groups of unwanted life forms.
 * It is the total rate of photosynthesis including the organic matter used up in respiration during measurement period.

3.3	Genetic diversity and species diversity. (2062) Ans: Genetic diversity	Species diversity
 * It refers to total photosynthesis or total accumulation.	* It is the rate of storage of organic matter in plant tissues in excess of the respiratory utilization by plants during measurement period.
 * It refers to the storage of biomass.
 * Genetic diversity refers to the variations of genes within living   organisms.


 * The genetic differences among population of a single species and among individuals within a population of a single species and among individuals within a population.
 * The diversity may or may not increase with decreasing latitude on earth.	* Species diversity is the variety of species on earth and in different habitats of the planet.
 * Measures of species richness are the basis for the observation.


 * The diversity increases with decreasing latitude on earth.

3.2	Predation and parasitism.(2063) Ans: Parasitism	Predation 1. It is the type of negative interaction in which one species is benefited i.e. parasite and other is harmed i.e. host. 2. Here host is not completely killed. 3. A smaller population gets benefited from large population e.g. Mosquito biting man. 1. It is the type of negative interaction in which one species i.e. predator is benefited and other is harmed i.e. prey. 2. Here prey is killed. 3. Large population get benefited from large population i.e. Lion eating tiger.

3.3	Food chain and food web. (2061, 2063) Ans: Food chain 	food web Grasshopper             Lizard Grass       Rabbit                          Hawk Mouse          Snake
 * The transfer of food energy from source i.e. Plants through a series of organism with repeated process of eating and being eaten is called food chain.
 * It is a linear arrangement of organisms showing transfer of energy.
 * E.g. Sun          Zooplankton           Small fish           Large fish           Man  	* food chain nature are never isolated but are interconnected with one another and form a sort of interlocking pattern is called food web.
 * It is a web like structure representing the transfer of food energy.
 * Eg.

3.4	Strip cropping and alley cropping.(2062) Ans: Strip cropping	alley cropping
 * It is the practice of growing crops that require different types of tillage such as row and sod, in alternate stripe along contureor across the prevailing direction of wind.
 * e.g. Legume and grass mixed cropping practice.	* It is the practice of planting of crops in stripe with rows of trees and shrubs on each side. It is also known as agroforestry or a form of inter cropping farming.


 * Tree and shrub mixed cropping practice.

3.27 Primary and secondary productivity.(2064) Primary productivity	secondary productivity
 * is defined as the rate at which radiant energy is stored by photosynthetic or chemosynthetic activity of producer organisms in the form of organic substances which can be used as food materials.

* Secondary productivity is the rate of storage at consumer level. Since consumer only utilize food materials already produced, with some respiratory loss and is converted to different tissues by an overall process, gross or net division is not appropriate
 * Primary productivity can be measured in net and gross terms and termed as production.
 * Secondary productivity cannot be measured in net and gross terms it termed as assimilation.

Extra Question: 	Discuss sulphur cycle. Sulphur occurs in the soil and rocks as sulphides (Zns, Fes etc) and sulphates which are crystalline. in the atmosphere sulphur occurs in the form of SO2 and H2S. SO2 gas is realease to atmosphere from water logged soils, lakes and springs. The organic and inorganic sulphur and SO2 are formed through oxidation of H2S in atmosphere. A small amount of sulphur occurs in dissolve state in rain water and it reaches to earth surface. Most of the organisms take sulphur as inorganic sulphates. Some needs organic form of sulphur. Most of sulphur which is biologically incorporated is produced in the soil from aerobic break down of proteins by bacteria and fungi. 2H2S + O2                       2S + 2H2O 2S + 2H2O + 3O2                      2H2SO4 Some bacteria use hydrogen of H2S as the oxygen acceptor in reducing CO2. In the ecosystem sulphur is transferred from autotrophs to animal, then to decomposer and finally it returns to environment through death and decay of dead organic materials as

Microbial ecology: 2.1	Describe biodeterioration of organic compounds.( 2055, 2058, 2060,2063) Ans: Biodetoriation is the spoilage or damage of organic compound. It is physical or chemical alternation of a product which decrease the usefulness of the product i.e. intended purpose is decreased caused by microorganism or their enzymes. 1)	Biodetoriation of agricultural products: The attack of microorganism on agricultural products like grains, pulses, meat and other products bring physical as well as chemical changes so reduce the nutritional value of food products. The microorganism detoriated products are poisonous due to the enzymes secreted by the microorganism. Aspergillum sps, Penicillium, Trichoderma, Fusarium, Mucor, Bacterial sps. are responsible for Biodetoriation of agricultural products. The organisms are Pseudomonas, Clostridium etc. 2)	Biodetoriation of pulpwood products and paper: In paper productions microbial activities are utilized in solublizing, which instead also cause loss. Microbial attack on paper quality low. Fungi are more responsible for the detoriation of paper than bacteria. The fungi species Responsible for the detoriation are Mucor, Penicicillum, Fusarium, Trycoderma and some Yeast species. The paper are subjected to detoriation, cellulose is susceptible to Fungal detoriation e.g. Alternaria, Aspergillus, Cladosporium. 3)	Biodetoriation of textiles (Fibers): Mucor is mainly responsible for the damage of cellulose. Fibres genus Myrothecium is responsible for the deteotiation of cellulose of fibres. Mucor growth is favored by high humidity. Moderate temperature and diffused light. The aerobic groups of bacteria can detoriate fibres because they have cellulose digesting enzyme. 4)	Biodetoriation of paints and painted surface: Microorganism can detoriate the paint and painted surface, the degree of detoriation depends upon chemical structure of organic material used and physical and chemical environment. Fungi are mostly responsible for the biodetoriation of paints e.g. Cladosporium, Aurcobasidium. 5)	Detoriation of other organic materials: Microorganisms like pseudomonas and Desulphovibrio are mainly responsible in causing detoriation of optical equipments.the plastic products are detoriated by Mucor, Penicicillum, Aspergillus, and Rhizopous. Microorganism detoriate petroleum e.g. Cladosporium resinae (Kerosene Fungus).Detoriation of concrete product by Thiobacilus thioxidans producing H2SO4. 2.2 Biological control of pests. (2055, 2058, 2063, 2064) Ans: The process which involves controlling of using chemical pesticide in agro ecosystem by using alternative methods of pesticides is known as biological pest control. Because of increasing genetic resistance of the pest, killing of natural pest enemies by the use of pesticides is ineffective. So alternative uses of pest control (biological pest control) are used which are as follows. 1. Changing the cultivation practice, it can be done by: a)  Changing the type of crop planted in a field each year (crop radiation). b)   Planting rows or hedges or trees around field to hinder insect invasion. c)  Adjusting the planting times so that major pest starve or get eaten by natural predator. d)   Growing crops in areas where major pests do not exist, switching from un vulnerable monoculture to polyculture agro forestry which use plant diversity to reduce the losses of pest. e)  Burning diseased or infected plant and other crops beside that remain in crop fields after harvesting. 1.   Development of genetically resistance crops; It can be done by crossbreeding through the genetic engineering that can resist the pest. 2.   Introducing of natural enemies to control of pests; Predators, pathogens and parasites can be encouraged or imported to  regulate pest population. 3. By controlling the birth rates of pests;  a. Sterilized by the radiation or some chemicals.  b. Released into the infected area to mate with the fertile females. 4. By spraying boiling water on the infected crops like cotton and potato field. But this method is more costly.   2.3 How do you justify that decomposers are the essential component of the environment. (2056) Ans: Our environment comprises many organisms’ producers, consumers and decomposers. These all play vital for the continuity of ecosystem .producer takes their nutrition from different sources like light from sun, water & organic nutrition from soil & these material is transported to the different producer levels & finally to the soil .the vital role of decomposer exist here .the decomposer decompose the material and then stored to the soil .if there were no decomposer then the energy be disturbance in the ecosystem so decomposer are the major components of the environment(see role of decomposers ). 2.4 Discuss the advantage and disadvantages of pesticides in the environment. (2057) Ans: Advantage of pesticides 1.disease control :- a) insect and ticks serve as vector in the transmission of a number of disease causing pathogens & parasites .e.g. by controlling mosquitoes save one million lives per year in tropical countries b) Viral disease, encephalitis, river blindness, dengue etc all these can be reduced by judicious use of pesticides. 2. Crop protection :- it is though that plant diseases, insect & bird predation and competition by weeds reduce crop yields worldwide by at least one- third. Pesticides problem :- 1)	Effect on non-target species : It is estimated that up to 90 % of the pest, we use never reach their intended targets as a result, many beneficial organisms are poisoned unintentionally. 2)	pesticide resistance and pest resurgence i) Pesticide almost never kills 100% of a target species. ii)  Every population contains some diversity in tolerance to adverse environmental factors. iii) The most resistance members at a population survive pesticide treatment and produce more off-springs, the population quickly rebuilds with pesticide – resistant individual. 2.5 Discuss the role of microorganisms as food.(2059) Ans: Bacteria as a source of food:- I. Single celled proteins are produced from waste material by using some species of pseudomonas II. Dairy products: - butter, cheese, curds are produce by lactobacillus, lacidipium.. III.Industrial food products:-Vinegar is produced by Acetobacter, Mycoderma, and Citrovorum. IV. Fermented food:-yeast & mold help in preparation of alcohol. Various Fermented food like pickle .These are produce by the activity of streptococcus. 1) Cyanobacteria as source of food:-blue green algae, nostoc commune is consumed as vegetables in china, Japan. it is also used as animal food. 2) fungi as a source of food :- Different kinds of mushroom like Agaricus campestrisare used                                                            as nutritious food.        Ii.Ripening of milk products: - in dairy industries, different kinds of mycota sps are involve to convert lactogen to lactic acid .eg:-mucory Ruinous. 4) Algae as a source of food: - algae are rich in carbohydrate, many organic & inorganic substances and vitamins. 2.6What are different processes of waste water treatment? (2059) Ans: There are mainly three process of waste water treatment they are: 1)  Primary treatment: It refers to mechanical process to remove coarse sand, suspended solid etc. before to apply primary treatment process for waste purification pre- treatment is require. It reduces the bulk load of pollutants. * It reduces the fees for its disposal. In primary treatment following process are applied. a) Screening:   It remove pollutants which can log (Block) V shaped notch wire or pipes and values. b) Girth removal:  It removes girth from raw sewage in early sewage in early stage and prevents rupturing of pumps and other mechanical equipments. It avoid accumulation of inert solid in primary sludge by removing girth heavy particles are removed out. The diameter of girth is 0.2 mm. All such types of particles along with suspended solids are removed out. c) Sedimentation:   Setting of sewage is to remove from waste water so as to reduce the load for biological treatment units. Setting of sewage should be in range of 1.25m/hour and hydraulic retention time might be 2-2 hrs. Sedimentation process removes coarse, suspended solids, BOD, referactory organics etc. Further treatment process can be done on the some sedimentation tank by adding chemical substances. 2)  Secondary waste water treatment: Since much of the organic material in waste water may be colloidal or dissolved primary treatment is ineffective in remains. It is done by two ways; they are  1) Activated sludge treatment system and 2) Trickling filter. 1) Activated sludge treatment system: here in this process the waste water is brought into the contact with a diverse group of microorganism in the form of flocculent suspension in an aerated tank. 2) Trickling filter: Here in this process the waste water is brought in contact into mixed microbial population in the Glena of slime attach with the surface of solid surface of solid support medium. In both these cases, the organic is metabolized to move stable inorganic form. This common unit operation or thickness, digestion, conditioning, dewatering, oxidation and finally disposal. 3) Advance waste water treatment: During tertiary waste water treatment process phosphorus is removed out from waste water. If nitrogen and phosphorus concentration is excess in waste water, eutropication problem may create. It takes place to: a) Removal of suspended solid.	b) Nutrient removal (nitrogen and phosphorus removal). c) Removal of dissolved solid.	d) Removal of inorganic material. 2.7Describe the microbial interactions in the environment.(2058,2060,2063) Ans: Microbes make different associations and interaction among them and with higher animals, plants. Different microbes interact in different ways in environment. The microbial interactions are responsible for regulation of population and viable existence in nature. There are two types of interactions; they are positive interaction in which both or either species is benefited and negative interaction in which both or either species are harmed. 1)	Neutralism: Neutralism has not interaction between two populations. It cannot take place in the organisms having same or overlapping function. It is likely to occur in the populations which are functionally differing from each other. It may occur or may take place in marine habitat or oligotrophic lakes. 2)	Commensalisms: In this situation one population benefits while other remains unaffected. It generally occurs when one population on its normal growth and metabolism changes the environment or system which becomes favorable to other population. The facultative aerobic microorganism use oxygen and create favorable environment for anaerobic (obligatory) microorganism. The obligate aerobe benefits from facultative anaerobes but aerobic microorganism are also not badly affected. Some fungi produce extracellular fungi which decompose cellulose materials and produce glucose from which other microbes may get benefited. 3)	Proto cooperation (synotrophism): It is the relationship between two populations in which both are benefited but it is not obligatory relationship. Here two populations supply each others requirements. Synotrophism is the relationship between two populations in which the populations are capable to synthesize the materials which can’t be synthesized alone. e.g. usually thousands of pathogens are required to cause disease as a single pathogen is rarely become host defence. 4)	Mutualism: In mutualism there is an intimate or obligate relationship between two populations. Lichens are good examples in which fungus and algal species are mutually associated for complete metabolism. The algal thalli perform photosynthesis while fungal part absorbs the water and other nutrients. 5)	Ammensalism: It is a kind of negative interaction in which one population harms the other but in turn remain unaffected. When a population stabilizes itself in environment it prevents attack of other species e.g. E-coli can’t grow in rumen because of presence of volatile fatty acids produced by heterotrophic population. Acid produced by microbial population in vaginal tract are responsible for preventing from infection of pathogens such as Candida albicans. 6)	Predation: It is one of the negative interaction in which one population is prey and other is predator. E.g. the ciliates, flagellates and amoeboid population prey upon bacterial population. This relationship is responsible for the maintains of bacterial population in balance in soil and aquatic systems. Microbial interactions in the environment are 1)	Animal-microbes interaction: this is the mutual relation with microorganisms. Although plants are the main source of food, they do not produce cellulose digestive enzymes by themselves. Microbial compression is which are present in the rumen at stomach of animal produce cellulose digestive enzymes. Those microorganisms digest the plants materials i.e. cellulose and also provide constant temperature. Ruminant animal are also helpful for microbes. In this case bactericides and Ruminococcous sps. are present in the rumens of stomach. 2)	Microbes –plants interaction: Root nodules of leguminous plant consists of nitrogen fixing bacteria i.e. Nitrosomonas sps, and Nitrobacterium. The bacteria fixes atmospheric nitrogen into nitrite and nitrate. Only nitrate is utilized by leguminous plants as a fertilizer. It is one of the examples of microbes and plants interaction. This is also known as symbiotic relationship. Microbes interact with microorganisms: Penicilium sps produce penicillin which inhibits or suppresses the growth and development of other fungi and bacteria. In the same community or source both the organisms cannot develop at the same time. The toxic activities of penicillin masks over the other microbes’ activity. This is also known as antibiosis. 2.8	Farmers always like to spray pesticides in their crop fields. Do you agree with this view or not? Write your opinion with reasons.(2059) Ans: Any chemical which causes the capacity of suppressing or eliminating unwanted organisms while causing non or nominal damage to desired organism are known as pesticides. It is not good to spray pesticides in crop fields. This is because using of pesticides leads to the disturbance in agro ecosystem. Also use of pesticide is major cause for water, soil and air pollution. Though the desired pest can be controlled but if a lot of pesticide is used, it leads to the damage of crops, decrease soil fertility and nitrates content in the soil. This leads to the damage in agricultural land. Also excess use of pesticide may develop resistant power in pest which may create problem in controlling pest afterwards. So it is better to use biological methods to control the pests. In natural ecosystem, natural enemies (predator, parasites etc.) control the population of pest. So it is not always good to use pesticides in the crop field as it alters agro ecosystem, less productivity and low fertility of land. 2.9	Write down in brief the effects of microorganisms on food.(2061,2062,2064) Ans: Bacteria and fungi are mainly responsible for the spoilage of food may take place in any time, the spoiling micro organism change the culture and odor and color of food. 1)	Bacterial effect on food: Bacteria spoil and poison the food. 	Spoilage of food: Many of the saprophytic bacteria decay foods like rotening of vegetables, fruits, meat, fish, breads, souring of milk, cheese, butter, jams and pickles. Saprophytic bacteria: Pseudomonas, Clostridium bacillus. Putrification: Spoilage of microorganism like proteolytic microorganism forming micro organism forming amino acids, amine, NH3, H2S. 	Fermentation: Contamination of carbohydrates by carbohydrate fermenting micro organism forming acids, RDH. 	Fancidity: Spoilage of fats by lippolytic microorganism forming fatty acids and glycerols. 	Spoilage of milk: The proteins are decomposed by pectolytic microorganism to give slimy milk with pigmentation and odor. 	Poisoning of food: microorganism make the food poisonous by secretion of toxic substances. Bacterial food poisoning is of four types: 	Botulism: It is the most dangerous and fatal type of food poisoning caused by Clostridium boutulina, which is obligate, anaerobic, endospore forming gram positive bacteria. It produces exotoxin in canned foods, consumption of such food cause paralysis of pharynx and diaphragm through its effect on nerves. 	Bacillus poisoning: This is due to Bacillus cereus it occurs in preserved food. It causes colic pain, diarrhea and vomiting. Bacillus aerothermophelus and Bacillus thermodifference are responsible for the disease. 	Staphylococcus poisoning: Due to Staphylococcus aureus cause diarrhea, vomiting, Nausea, which occurs in preserved vegetable foods. 	Salmonellosis: It is caused by Salmonella enteridis and Salmonella typhimurium which contaminate the food like meat which lead to Salmonellosis characterized by Chills, Nausea, diarrhea, vomiting. 2) Fungal spoilage: The spoilage of food is by fungi and mucor (moulds) which produce the secondary metabolites called as mycotoxins. These toxins make the food inedible. E.g. Fumacin                           Fusarium moniliforme. Patulin                                      Fusarium penicilium Tricothecens.                           Fusarium tricotherma Mycotoxins are carcinogenic (cancer causing), mutagenic, teratogenic (embryotoxin), hepato toxin (liver toxin), neurotoxin (nerve toxin), narcotic (death of tissue), haemorotoxic (blood toxin), alfo toxin produced by Aspergillum flavor, Aspergillum parasiticum.  2.10   2.11   Discuss the distribution of micro-organisms in the environment.(2057) Ans: Micro-organisms are distributed in all the spheres viz atmosphere (air), hydrosphere (water), lithosphere (soil) and biosphere (living organisms). Hydrosphere and lithospheres are the suitable environments for micro-organisms. Several types of bacteria, protozoa, helminthes, fungi, algae, worms, and insects are the important part of hydrosphere and lithosphere. These micro-organisms play crucial role of decompose dead and degraded organic substances and help to continue several biogeochemical cycles in water, soil and air. In many cases, micro-organisms are found inside or outside living organisms. Sometimes, these micro-organisms are beneficial to the host organisms or harmful or neutral in other cases. However, atmosphere is not suitable environment for micro-organisms. In atmosphere, the micro-organisms are found in atmospheric particles and water droplets suspended in the air. 2.12	 3.1 Actinomycetes and cyanobacteria.(2055, 2059, 2064) Ans: Actonomycetes	Cyan bacteria
 * Avoid the damages to the sewer system.
 * Absence of pigment phycocyanin
 * Absence of chlorophyll
 * Absence of symbiotic forms	* Presence of pigment phycocyanin
 * Presence of chlorophyll
 * Presence of symbiotic forms

3.2	Pesticides and herbicides. (2055) Ans: Pesticides	Herbicides
 * These are the chemicals used in an effort to inhibit or destroy undesirable life forms, which are considered a nuisance (things which trouble some).
 * These are the large group of chemicals including herbicides are pesticides i.e. all herbicides are pesticides. E.g. Insecticide, fungicide, herbicide.	* These are the chemicals used in an effort to inhibit or destroy undesirable life forms, only by green weed and plants which are considered as nuisance.
 * These are the small group of chemicals including under pesticides. i.e. all pesticides are not herbicides e.g. arsenous oxide, sodium arsenite, chloro phenoxide acid.

3.3	Storage reservoir and detention reservoir.(2056) Ans: Storage reservoir	detention reservoir
 * Here water collected is stored in a large tank like reservoir.
 * It should be of large size to store large amount of water.	* Here water is collected from many sources of water.
 * It may be small size also. It leads to detention reservoir.

3.4	Bacteria and virus. (2062) Ans: Bacteria	virus * The virus contains only one of RNA or DNA.
 * Bacteria contain both RNA and DNA.
 * Bacteria are found in all possible habitats.
 * Bacteria are beneficial as well as harmful to plants and animals
 * Viruses are obligatory parasite, they are found only in living cells.
 * Viruses are mostly harmful to plants and animals.

Geology 1.1 Discuss different process of weathering rocks and their role in the environment.(2055, 2059) Ans: Weathering is a combination of destruction and synthesis. Rock weathering is a phenomenon of the interface between the atmosphere and lithosphere. Rocks exposed to the surface are brought to a new environment that is quite different from those in which rocks were formed and they are acted upon by various natural agencies as a result of which they undergo several changes. Generally the term weathering is applied to the combined action all processes causing rocks to be disintegrated physically and decomposed chemically because of their exposure at or near the earth surface. In general weathering occurs, when rocks and minerals come in contact with the atmosphere, surface water and organic life. It is a process where the solid rocks of the earth’s crust are broken down to form parent material of the soil. There are three types of weathering of rocks: 1) Physical weathering: It is the mechanical disintegration of rocks without change in chemical properties. Due to physical forces (temperature, pressure, frost etc.) the rock undergoes fragmentation. No new substances are formed due to physical weathering. Physical weathering promotes a fine state of division, which is necessary in the soil. Agencies of physical weathering: a)	Temperature: High temperature accelerates the process of weathering especially in humid region. A rock is poor conductor of heat; a high temperature extends up to a certain depth and the greater expansions of rocks at the surface produces a strain which causes a layer to break off. This cause mineral to loosen the crystals and rocks crumble. The crumbling of rocks in dry climates due to free radiation temperature changes at sunset and sunshine which is called exfoliation. b)	Freezing and thawing: Porous rocks are disintegrating by this process. In cold and temperate climate where precipitation is abundant, the rocks roll down the slope as they get enlarged by thawing, freezing and finally the weathering takes place. c)	Glacier: Glacier are drainage system of the region of perpetual snow, these have a greater grinding power to disintegrate the rocks. The glacier transports the rocks in some extent. d)	Water: Water with their load of clay, silt and gravel deepen and widen valleys grind the rocks for soil formation. This agent acts as disintegrating transporting and depositing agent. e)	Wind: The movement of wind with sand particles causes abrasive action on rocks and on minerals contained in rocks. Wind makes the action of sea waves stronger in coast and cause weathering. 2)	Chemical weathering: The weathering in which the original rocks are decomposed and new substances are originated is called chemical weathering. In this weathering certain minerals disappear either partially or completely and minerals of secondary origin are formed which are totally different from the parent minerals. Agents of chemical weathering: a) Hydration: This consists of chemical combination of water with a particular mineral and it mainly occurs in humid regions. Due to hydration volume of rock increases and become soft. Hydration is non-pedagogic process as it also occurs under conditions remote from the operation of ordinary atmospheric agencies. e.g. 2Fe2O3 + 3H2O                  2Fe2O3.3H2O (Hematite) b) Oxidation: The addition of oxygen to various mineral is called oxidation. Soil         minerals containing Fe, Mn, Sulphides are more subjected to oxidation. FeO + O2		Fe2O3 Ferrous oxide                 Ferric oxide c) Carbonation: The reaction of compound with carbonic acid is called carbonation. It results in the formation of bicarbonates. H2O +CO2                  H2CO3 Carbonic acid H2CO3 + CaCO3                  Ca (HCO3)2 d) Hydrolysis: It is the process of exchange reaction between the bases of minerals and hydro [H+] ions of dissociated part of water. Water dissociates into H+ and OH- ions. Acidity and alkalinity of water is measured by H+ concentration or pH value. The higher the pH value, the more it is dissociated so greater the action as chemical weathering agent.	The rain water mixed with carbonic acid, a chemical agent. H2O + CO2		 {H+ + O + CO3-}		H2CO3 2 KOH + H2CO3 			K2CO3 + 2H2O MgFeSiO4 + 2HOH  			Mg (OH)2 + H2SiO3 +  Fe (Olivine)      (Water)				      (Silicia acid) e)	Solution: Some of minerals get dissolved by water and thus removed in solution. Solution taken place at different rates for different rocks. Maximum degree of solution is found to be with chlorides halite (NaCl), sylvite (KCl) etc. Sulphates nd carbonates are less soluble. Joint action of CO2 and H2O enhances the +ve effectiveness of process of solution. Silica although a stable mineral, undergoes solution in alkaline fluid. The process of removal of solution minerals from the rocks in solution by percolating H2O is leaching. 3)	Biological weathering: The process of weathering which are mainly related to activities of plants, animal and organisms like bacteria etc. are known as biological weathering. It involves the role of plants and animals in the breaking down of rocks through mechanical ways as well as in decompositions of rocks. When a small amount of soil forms in rock crevices plants begin to grow, containing life cycle of algae, lichen, and mosses kept the rock surface moist and help chemical weathering. Burrowing animals like (rats, rabbit) rodents expose rock surface weathering. 1.1 What are geological agents of environmental changes? Describe the most serious natural hazard in Nepal. (2055) Ans: Geological agents of environmental changes are land slide, erosion, glacier, river flooding, wind( particularly in desert areas), earthquake, volcanoes etc. The most serious natural hazard in Nepal is land slide. The outward and downward motion of slope forming material under the influence of gravity by falling, sliding or flowing along the surface of separation at a faster rate is called landslide. A landslide occurs when the seaving stress exceeds the capacity of underlying support. There are various factors to cause the land slide. Some of them are-: I. Natural factor: a) Step slope, b)  Undulating of the banks of rivers by abrasive action of river itself. c) Type of rocks: If there exist weaker rocks like shalk slate, phylite, which can be easily 	weathered. d)  Triggering: Cloud burst (rainfall of 200 – 1000 mm per day) may cause uncontrolled 	flow of water on slope surface. e) Earthquake vibration II. Anthropogenic causes: a)	Deforestation. b)	Improper land use pattern.	I. Agricultural practice on steep slope.	II. Irrigation on steep and vulnerable slope.	III. Overgrazing.	IV. Grazing for construction material without considering the condition of train. c)	Construction activities: construction of roads, cannels in hill side, slope cutting action causes land sliding. Too cutting of landslide may activate failure of the land, vibration cause by blasting. Effects of landslide in Nepal in different regions are: a)	Land slide in himalaya: The himalays have young immature and rugged terrain. Due to fragile geologic and geomorphic condition himalaya is highly suceptable to the factors causing landslides. The streams and rivers with light gradient are the most important agents of mass wasting and almost all the geomorphic and geologic zones of himalays are vulnerable to landslides. b)	Land slide in siwalik: Silawik range have young topography with loss and unpacked sediments. The materials are sandstones, mudstones, shale layers and conglomerate. These are vulnerable to rapid weathering. Conglomerate in particular is unconsolidactes, loose and can be easily weathered. This region receives rainfall of 1000 to 1500mm. The southern slopes are steep. This condition triggered them to landslide. c)	Land slide in mahabharat: Mahabharat range has easily weathering rocks like phylite, slate etc. Some parts with dolomite, gneisses are stable. d)	Land slide in Midland: Midland has deeply weathered rocks, thick soil covers. The rainfall is also high in this region. Human activities of slopes for farming and settlements. The rivers in the bottom of the valley deeply incised cutting the base of slope, irrigation practice. Deforestation significantly makes the unprotected slopes vulnerable. 2.1  Classification of sedimentary rocks. ( 2055) Ans: The rocks resulting from the consolidation of loose sediments or chemical precipitation from the solution at or near the earth’s surface is known as sedimentary rocks. e.g. Sandstone, limestone, mudstone etc. Sedimentary rocks are the secondary rocks. Sedimentary rocks are formed by the accumulation and compaction of either fragment from pre – existing rocks which have been disintegrate by weathering and erosion, organic debris such as shell fragment of dead organism or material dissolved in surface water or ground water which is precipitated in the condition of over saturation. The sedimentary rocks can be classified on the basis of 1.Mode of Formation	 	2. Texture Mode of formation Depending upon their mode of formation and mechanism of accumulation and consolidation, sedimentary rocks may broadly be classified as, i.)	Mechanically formed or clastic sedimentary rocks: Rocks formed due to mechanical consolidation of loose sediments. The consolidation is brought about in two ways. a) Welding and b) Cementation. ii.)	Residual deposits or sedentary rocks: These kind of the rocks are formed due to accumulation and consolidation of those materials which were left as residue during the operation of the processes of weathering and transportation. These are usually partially consolidated. eg. laterite. iii.)	Chemically formed sedimentary rocks: Rocks formed by the precipitation or evaporation and consequent accumulation of the soluble constituents of standard solution. eg limestone, dolomite, rock salt etc. iv.)	Organically formed or biochemical rocks: The rocks formed by the huge accumulation of remains of organisms, plants or animals preserve under suitable condition, compacted or self cemented. e.g. fossiliferous limestone, coal, deposits. Based on the Texture the sedimentary rocks are 1) Rudecious rocks: these are very coarse grained rocks where the size of the grain is those of boulders. The grain size diameter is generally >2mm. These are transported in fraction e.g. Conglomerate. 2) Arenaceous rocks: These rocks consists cheaply particles as the size of sand. The grain size ranges from 0.062 mm to 2 mm. e.g. sand stone. 3)  Silt rocks: Here the constituent particles are finer than common sand and coarser than clay. They are transported by suspension; e.g. silt stone. 4) Argillaceous rocks: These are made up of clay particles, usually transported in suspension; e.g. clay stone. 2.2 Discuss the role of tectonism and volcanism in the environment.(2056) Ans: A dome shaped hill or mountain formed by the extrusion of lava or any pyroclastic material from a vent is known as volcano. It can be also defined as the vent through which the molten rock materials and associated gases are erupted to earth’s surface. The term used to indicate all the phenomena related to the eruption of magma to earth’s surface is called volcanism. Each year several dozen of volcanoes erupt on earth. Great loss of lives and properties and damage to the environment is caused by volcanism. The complex and variable products of volcanoes include toxics gases, liquids and solids. The volcanic liquids are acidic, medium and basic. The flowing lava can cover roads and villages and cause firing on forest and settlements. The volcanic Gases composed of largely water vapours (60-90) and other gases are CO2, H2S, Cl, N2O, SO2, H, CO, S, HCl, N2 etc. The gases emitted remains in atmosphere and are converted into tiny droplets of acid, many of which stay above the cloud and may not be washed out by rain for years. These tiny droplets reflect some of the solar energy and can cool the atmosphere. The emanated fumes of Hydrochloric acid, Boric acid, and arsenic acid as well as sulphuric acid fall back during rainy season in the form of acid rain which also causes lots of damage in biotic and abiotic component of the environment. Mainly the cultural monuments are highly affected by the acid rain. We tend to think negative activity of volcano but it also provide some benefits like outstanding scenery in the form of majestic mountains, some lakes and other land formed to live on. The process that involves breaking and bending of the earths crust under internal earth’s forces is known as tectonic movements. 2.3 Explain the causes and effect of landslide.(2056,2059) Ans: The downward and outward movement of slope forming material along surface of separation by falling, standing and flowing at a faster rate is called land slide. Causes of land slides: There are various factors to cause the land slide. Some of them are-: I. Natural factor: a) Step slope, b)  Undulating of the banks of rivers by abrasive action of river itself. c) Type of rocks: If there exist weaker rocks like shalk slate, phylite, which can be easily 	weathered. d)  Triggering: Cloud burst (rainfall of 200 – 1000 mm per day) may cause uncontrolled 	flow of water on slope surface. e) Earthquake vibration II. Anthropogenic causes: a ) Deforestation. b ) Improper land use pattern. I.	Agricultural practice on steep slope. II. Irrigation on steep and vulnerable slope. III. Overgrazing. IV. Grazing for construction material without considering the condition of train. f)	Construction activities: construction of roads, cannels in hill side, slope cutting action causes land sliding. Too cutting of landslide may activate failure of the land, vibration cause by blasting.

Effect of landslide: The vegetation carpet of hilly region is removed by landslide affecting the local ecosystem as well as to huge amount of upper fertile soil layer is washed out by it. Landslides cause loss of life and property on settlement area and also damage many of physical structure like roads, bridges, canals etc. Sometime the landslide may block the flow of river caused damming of water for temporary and when it burst that may cause flooding to downstream and causing great losses of many things. Also cause diseases. 2.4 What are the different causes and effect of earthquakes? (2057,2062) Ans: Earthquakes are sudden temporary vibrations caused by movements of rocks. It is a form of energy in wave motion which originates in a limited region and then spreads out in all direction from the source of disturbance. There are mainly two causes of earthquake that are tectonic and non-tectonic. Tectonic: Most of the earthquakes are due to earth’s movement along existing or non faults, such quakes are called tectonic earthquake. Tectonic forces on rocks build up a very large storage of energy over a period of time. The energy is stored by deformation in the rocks when this energy is exceeds the rock sequence breaks and displaces which we called faulting. During the displacement of rock previously stored energy suddenly release out in the form of seismic waves. These waves are capable to move the rocks or shake the earth surface called earthquake. Non-tectonic: These include the causes associated with the geological agents operating on earth surface. a) Surface causes (Natural): 	Descending of running water from a higher altitude. 	Dashing waves and crashing breakers. 	Rocks fall or avalanches. 	Large land slides. Surface causes (Artificial): 	Under explosion. 	Failure of dams. 	Mining and construction. 	Passage of trucks and trains. b) Volcanic causes: 	Explosion of volcano upon release and expansion of gases and lava. 	Faulting within volcano resulting from pressure in the chamber of molten rock. 	Collapse of centre of volcano into space formed by extrusion of gases and molten magnetic materials. c) collapse of subterranean cavity: removal of support from below by the action of underground water, the ground surface collapse suddenly producing tremors. Effect of earth quake: Most of earthquake does little harm such as stopping pendulum clock, rating table ware but in every few years a great earthquake happens near enough to a population centre to wide speed devastation. Earthquake is a natural disaster of such a type that it never gives opportunity to people to save their life and escape. Damage of earthquake varies with the strength of earthquake, local geology, type of building construction and life support system. Due to vibration of ground, building, bridges, dams, poles, fences etc. may be slightly or heavily damage and people are hit by following debris from buildings. Railways are buckled and twisted. Ground water and its management get disturbed by earthquake. The course of streams and rivers may change. In addition to these damage done by earthquake itself further devastation may result from other natural events triggered by earthquake as slopes failure, tsunami and fires. The epidemic diseases are also spread by the earthquake. 2.5Describe the internalstructure of the earth. (2057, 2058, 2061, 2064) Ans: On the basis of seismic investigation, the internal part of earth is broadly divided into three parts; crust, mental and core which are separated by two sharps break usually known as discontinuities. 1) Crust: It is the uppermost thinnest layer of the earth composed of heterogeneous materials. The thickness varies in ocean from 5-10 km and continental area from 35-50 km with average thickness of 33 Km. The earth crust consists of verifying layer from (10- 40) Km. in thickness. The lower the boundary of crust is marked by Mohorovicic discontinuity. The rock rigidity increases with increases in the depth of crust. It consists of two layers, upper the sial and lowers the sima. 	Sail: It is also known as the upper continental crust. It consists of all type of rocks (Sedimentary, metamorphic, igneous) and granite composition. This layer is rich in silica and alumina.	Sima: It is also known as lower continental crust. This layer is rich in silica and magnesium. 2) Mantle: It is the second major part of the interior of the earth which extended up to 2865 km, which is the source region of the most of the earth internal energy. A thick solid zone which surrounds the earth’s core is called mantle. From the Mohorovicic discontinuity to the depth of 410 Km. there is a gradual decrease in seismic velocity which is known as Gutenberg layer. Most of the mantle is solid rock but under this rigid zone, plast zone which is called as the nosphere is found. Mantle is also divided into two parts. Lower mantle and upper mantle: Upper mantle: This mantle rock is at a temperature very close to its melting point. It extends from Moho to 1000 Km. It is called plastic layer or soft layer. Lower mantle: This is the layer where the rock has less strength and brittleness which break by Faulting when unequal stress is too long. Its layer extends from 1000 Km. to Gutenberg discontinuity. 3) Core: It is the innermost smooth dense sphere portion of the earth. Temperature at the centre of the core is 4500°c and density is 135gm/cc. The molten liquid which moves in an electric conductor that generates the earth’s magnetic field. The liquid molten part of the core move due to rotation of the earth, thermal conventional current. Inner core has the radius of 1255 Km. The mass of the core is 32% of the masses of earth and 16% of the volume of earth. P-wave velocity decreases sharply and S-wave can’t transmit. It extends from 2900 Km. to center of the earth i.e. 6371 km. It consists of three parts i.e. Outer core, middle core and inner core. 2.6	 Discuss the role of wind in geological change.(2058) Ans: Wind is moving air. The differential heating of atmosphere by solar heat causes wind to blow. Wind is an agent for active erosion and deposition in desert and semi desert areas and is capable of producing distinct land forms. The geological action of wind can be divided into three stages: a)	Erosion b)	Transportation c)	Deposition a)	Wind erosion: wind erosion is manifested by following process: 1)	Deflation: Deflation is the lifting and carrying of loose particles of clay and silt size. The rate of deflation depends on the force of the wind, the nature of the rocks and the degree of weathering.	2)	Abrasion: The loose particle that are blown away by the wind abroad the surface of rock state. The surface of rock is polished and covered with striations depending on the hardness of rock. 3)	Attrition: Mutual collision of particles blown by wind, which brings about some degree of grinding of the particles. The rounding of the grain becomes perfect and the grains are reducing to smaller dimension. b)	Wind transportation: Wind is the active agent for transporting fine particles. The process is maintained by : 1)	Suspension: The particles of diameter less than 0.05 mm. are transported in the form of dust, cloud and remain in air for sometime and settle very slow.	2)	Saltation: Medium sized particle having diameter between 0.05mm. to 2mm. are transported by hoping activities. This cause rolling of the particle and it bounce up into air, travels some distance in parabolic path and strikes the ground with considerable force and this leads the particle to bounce again or makes other particle to bounce. 3)	Surface creep: The particles larger than that can’t be transported by salvation are transported by rolling and creeping along the surface. c)  Wind deposition: Whenever the velocity of wind is checked due to some reason, a part or a whole of the transported loads starts to get accumulated. The process of accumulation of transportation material is known as deposition. These all activities of the wind forms various type of topography in the earth surface. 2.7	 Describe the mineral resources of Nepal.(2059) Ans: The kingdom Nepal lies in the central sector of 2400 Km. long Himalayan arc. From south to north it is geologically divided into 5 major zones, the Terai, the Siwalik, the lower Himalaya, the higher Himalaya and Tibetan Tethys zone. Geologically, studies showed that the Terai may be considered important for oil, natural gas and ground water resources. The siwalik is the zone in which coal and potential radioactive materials are found. The lesser Himalaya is important metallic, (cupper, zinc, lead, gold etc.) and non metallic deposits (limestone, magnetite, prosperity, coal etc.) and the high Himalaya have shown prospects for natural thing. When we think about mineral resource we generally think only about the metallic mineral deposits. The non- metallic minerals are also equally important and essential minerals. These are also other categories of useful geological materials such as fuel minerals like coal, petroleum and natural gas, precious and semi- precious stones, construction material and dimensional stone. Therefore, when one refers minerals potential Nepal not only metallic deposits but all these kinds of resources are to be considered. 2.8	Discuss the major impact of mining.(2061) Ans: Since the time of Stone age, human’s beings are making use of all type of natural resources. By the time of iron and bronze they started exploiting various types of natural resources like minerals, water, rock etc. and making multiple uses of them. Now a days, rocks and minerals are used as construction materials, decorative stones, ornaments, industrial chemical, fossil fuels etc. Therefore to fulfill the present public demands all these natural resources are so much exploit and use that they are creating adverse effect on the natural environment. Mainly two types of mining operation are carried out i.e. out open cast mining and underground mining. The open cast mining brings the visible changes in the landscape such as deforestation, soil-erosion, landslides and lowering of the ground water level etc. Beside dust, smoke and other gases emission from mining sites cause the air pollution. Due to operation of compressions, drilling, sawing, polishing etc.; As a result surface water as well as ground water get contaminated. Under mining is responsible of subsidence of the ground. The flow of ground water may change. The underground water may be contaminated through the using and production of different chemicals in mining operation and sludge produced. 2.9	Justify that the earth is a closed system.(2062) Ans: The most fundamental concept of geology is that the earth is dynamic body evolving through time. The earth undergoes important reactions driven by various energy sources like external energy, solar radiation, internal energy and geothermal heat etc. All those types of energies operate a cycle on and within the earth surface what we called geological cycle. James Hutton developed a concept which become the main basis for the study of dynamic behavior of the earth and the concept was “present is key to past”. On his published book, he put forward the concept of geological cycle as hydrological cycle and rock cycle. 1)	Hydrological cycle: the sun evaporates the water from ocean and form clouds which drift over the land drop their water as rainfall or snow. The rainfall shifts into the ground or flow over the surface and eventually return to sea. 2)	Rock cycle: the moisture attacks the bed rock. As a result the bed rock breaks down into masses of loose particles called regolith. When regolith becomes transported, it is named as sediments; they are changed into sedimentary rocks. These rocks have undergoes on extreme change in constituents caused by heat pressure and or chemical action. During folding, faulting and thrusting it is named as metamorphic rock when the pressure and temperature is increased, these rocks are changed into molten mass called magma. The magma during volcanic activities of earth comes out to the surface of the earth and cooled and finally changed into igneous rocks and by erosion all these rocks (Sedimentary, igneous, metamorphic) are changed into sediments and so on. These hydrological and rock cycle shows that these cycles occurs within earth creating and destroying it without loosing any things so, earth is said to be a closed system. 2.10  Biosphere & lithosphere.(2057) Biosphere: - The biosphere is defined as that part of the earth in which life exists. Most organisms require water & sunlight it is limited to region providing ample quantities of available water and energy from the air .the maximum range of biosphere is about 20 km thick with organism variously distributed from the depth of the ocean to the highest mountain peaks. Lithosphere: - the uppermost part of the mantle is the lithosphere or “sphere of rock” which includes the rocky material of the outer part of the earth .the upper part of the lithosphere is completely covered by the crust, a thin, rocky layer about 25 to 40 km thick beneath .the continents and about 5 to 10 km thick beneath the deep oceans. So the lithosphere is a rocky zone having some strength floating over asthenosphere, a zone within the upper mantle having negligible strength. Beneath the oceans, the lithosphere extends down to a maximum depth at about 100 km. beneath the continents; the thickness of the lithosphere is 110 to 200 kms.

3.1	Focus and Epicenter.(2056) Ans: Focus	Epicenter
 * It is the point within the earth where the earthquake waves originate.


 * It lies within earth surface.
 * From the focus, the vibration spreads in all directions.	* It is the point immediately above the focus at the surface where the wave first reaches.
 * It lies at the earth surface.
 * It is the most affected area during an earthquake.

3.2	Primary wave and secondary wave.(2056) Ans: Primary wave	secondary wave
 * They are also called longitudinal wave or push wave or ß- wave.
 * They travel in all media i.e. solid, liquid and gaseous medium.
 * They travel faster than transverse wave.
 * In this case rock vibrates direction parallel to the direction of propagation.	* These are called as transverse or shocking or shear or s-wave.
 * They only travel in solid medium.
 * They travel less rapidly than primary waves.
 * In this case the rock vibration is perpendicular to the direction of wave propagation.

3.3	Slum and Talus.(2057) Ans: Slum	Talus
 * It is an example of landslide.
 * Here the down slope movement of bed – rock mass takes place.	* It is an example of slow flowage.
 * Here the downhill movement of pieces of bed rock takes place.

3.4 Sedimentary and metamorphic rocks.(2058) Ans: Sedimentary rocks	metamorphic rocks
 * This rock is formed by the consolidation of loose sediments or chemical precipitation from the solution at or near the earth surface.
 * Presence of sedimentary like ripples marked cross bedding, mud, cracks, graded, bedding.
 * Common minerals are quartz, gypsum halite, anhydrite, clay mineral.	* This rock is formed by pre-existing rocks by mineralogical structure changes, esp. in solid state.


 * Distorted pebbles or crystal or fossils if present.


 * Common minerals are garment and alusite ,stauralite, kyanite, sillimanite, cordierite etc.

3.4	Creep and slump.(2060) Ans: Creep	slump
 * It is a type of slow flowage and consists of gradual, almost imperceptible down slope transit of soil & may sometimes take place even under the cover of vegetation.
 * In most cases, soil creep is essentially a surface phenomenon in which only the top 1 meter or so of the soil is involved in failure.	* It is a type of complex slide in which the nature of movement is rotational of movement is rotational & the material is of mixed character.
 * The soil falls along a single or multiple curved surface in such a way that its rear region tilts backwards while the toe portion bulges upward.

3.5	Minerals and rocks.(2061) Ans: Minerals	Rocks
 * These are naturally occurring substances.
 * They consist of only one mineral.	* These are aggregate of minerals.
 * They consist of only one mineral if they are mono mineralic and consist more then one if they are polymeneralic.

3.6	Chemical and mechanical weathering of rocks.(2062) Ans: Mechanical weathering	Chemical weathering
 * it is brought by the physical agents e.g. Heat and cold, freezing, glaciers, erosion, waves etc.
 * It brings about the disintegration of the rocks and minerals to small fragments.	* it is brought about by the chemical process e.g. oxidation, reduction.


 * it brings about the disappearance of certain minerals and formation of secondary products.

3.8 Mantle and core.(2062) Ans: Mantle	Core
 * It is the inner layer of earth or second last layer of earth.
 * p – Wave increases for 6.2 Km/sec. to 7.8 Km/s or 410 Km.below.
 * It extends from 33Km – 2900Km. towards the centre.	* It is the inner most layer of the earth or second last layer of the earth.
 * P – wave velocity decreases sharply.


 * It extends from 2900Km. to center.

Extra Question : Ans: Sedimentary rocks are formed by the accumulation and compaction of either fragment from pre – existing rocks which have been disintegrate by weathering and erosion, organic debris such as shell fragment of dead organism or material dissolved in surface water or ground water which is precipitated in the condition of over saturation. The sedimentary rocks can be classified into two categories clastic and non-clastic a)  Clastic rocks: these are detritus or fragmental rocks and are deposited by mechanical means of the geological agents. On the basic of mode of transportation the sedimentary rocks are classified as below; 1)   Rudecious rocks: these are very coarse grained rocks where the size of the grain is those of boulders. These are transported in fraction e.g. Conglomerate. 2)  Arenaceous rocks: These rocks consists cheaply particles as the size of sand; e.g. sand stone, aokose etc. 3)   Silt rocks: Here the constituent particles are finer than common sand and coarser than clay. They are transported by suspension; e.g. silt stone. 4)  Argillaceous rocks: These are made up of clay particles, usually transported in suspension; e.g. clay stone. b)   Non - Clastic rocks: these are formed due to chemical precipitation as well as by biological means. They are of two types. 1) Chemically deposited: These these are the rocks which are accumulated by chemical precipitation of over saturated solution. A system may be considered as a part of universe that is isolated in thought or infactfor the purpose of studying or observing changes that take place under various conditions.OR A part of universe or earth that is aside in our mind for special attention is called a system. Example of a system may include a volcano, a planet, an ocean basin etc. Most system contains various component parts which mutually adjust & each part exerts partial control on the others.eg- the earth may be considered as a system with four main component parts:the atmosphere, the hydrosphere,the biosphere & the lithosphere.The mutual interaction of these parts is responsible for the surface feature of earth today . further more any  change in magnitude or frequency or process in one part will affect the other parts e.g a change in magnitude of the processes that produce mountains may effect the atmosphere by releasing volcanic gas & causing regional changes in precipitation patterns as a new rain shadow is produced. This in turn affects the local hydrosphere as greater or less runoff reaches the ocean basin. Biosphere changes as a result of changes in environment also can be expected & eventually the steeper slopes will also affect the lithosphere by fascilitating increased erosion which in turn will change the rate & types of sediment produced & thus, the types of rock produced from the sediments. These interactions among the variables in system are not random & they can be understood by examining each variable to determine how it interacts over a site, area or region. For example in hydrosphere the spatial distribution of oceans with respect to sun affects the evaporation process of ocean water which in turn affects the decreasing the amount of water in the atmosphere. Earth is dynamic, in which the materials & energy are constantly changing. Such dynamic may be considered evidence that the earth is an open system with no boundary of energy or materials. This interpretation is applicable as long as the sun continues to impart energy to the earth. But of we consider natural earth cycles such as the water cycle & rock cycle in which there is continual recycling of earth materials, we think earth as a closed system or in reality the coalition of large number of closed system e.g.-the rain that falls today will eventually return to atmosphere, the sediment deposited yesterday will be transformed in to solid rock. Therefore although earth is currently and seemingly forever will an open system in terms of energy & material as is essentially a closed system in terms of natural earth cycles. The word volcano has been derived from island of Vulcano which lies at north east of sicily. A volcano is essentially a conical or dome shaped hill or mountain formed by the extrusion lava or other pyroclastic materials from a vent. Volcano is considered to be the most significant landform created by volcanism. Volcanism is the general term used to cover all the phenomenon related to the eruption of magma to the surface of earth. It is most important evidence of dynamic nature of earth & arises from the process which are endogenous in nature. Causes of volcano •	The origin of magma with its high temperature. •	The origin of volcanic gases & •	Extrusion of magmas Magma may be produced by:- •	Geothermal gradients i.e. increase of temperature with depth. •	Accumulation of radioactively generated heat. •	Relaxation of pressure locally. Types of volcano Volcanoes are classified into various types on the following bases 1.	continuity of eruption 2.	nature of eruption 3.	mode of eruption 1.	Continuity of eruption :- on this basis volcanoes are i. Active: - Those volcanoes which still erupt either intermittently or continuously. ii. Dormant: - Those volcanoes which have not erupted for a long time but are expected to be active at any time. iii. Extinct: - The volcano which has stopped eruption over a long time is called extinct. 2. Nature of eruption: On this basis factors like chemical composition of lavas, the amount of gas contained in them & their pressure, temperature etc.on this base, volcanoes are classified as quiet, intermediate and violent. i.	Quiet: - Lava erupts quietly without any explosion, basaltic composition of lava, little gas. ii. Intermediate:- Lava erupts intermediately with an explosion in the beginning and gradually explosion action dies down and lava is emitted quietly. iii. Violent:-These are explosive volcanoes having lavas of acidic composition and have high degree of viscosity & produces high quantity of pyroclastic materials. 3.  Mode of eruption:- On the basis of mode of eruption, volcanoes are classified as central type and fissure type. I.	Central type:- This type of volcanoes are represented by a bowl-like depression called crater and a vent, connecting crater with a magma chamber through which the eruption products reach the surface of the earth. II. Fissure type:- sometimes volcanic eruptions take place along a fissure or a group of parallel or closed fissures. Usually volcanic cones are not produced through fissures-eruptions lava flowing out of fissures spreads out over extensive areas forming lava sheets’; Deccan plateau in India.
 * 1) Classification of sedimentary rocks.
 * Evaporite: It is only due to evaporation and the deposits are like salt gypsum.
 * Siliceous: some organisms like diatoms can secret silica.
 * Calcareous: Shell fragments of mulluscans.
 * Phosphoric: Calcium phosphate is used up by some fishes and brachiopods and remains of these organisms may form phosphate deposits.
 * Ferruginous: By the activities of bacteria, fuliginous material may accumulate.
 * 1) Conceptual framework of earth as a closed system
 * 1) Volcanic Activity

Soil Science 1.1 Describe the composition of soil air and discuss the mechanism of gaseous exchange between atmosphere and soil air. (2058) Ans: Soil air has a higher concentration of CO2 and lower concentration of Oxygen than the atmosphere. The difference arises from respiration by soil organisms and plants roots and tends to be reduced by diffusion between the atmosphere and soil air. A well aerated soil is one in which gaseous exchange between the soil air and the atmosphere is sufficiently rapid to prevent a deficiency of O2 or CO2 toxicity. Plants carry on respiration, utilize energy and release CO2 which can be shown in a generalized equation. C6H12O6 + 6CO2                         6 CO2 + 6H2O + Energy. Under such condition the soil O2 become depleted and CO2enriched. Table: Composition of soil air: Table: Composition of the O2 and CO2 in a poorly drained silty loam at different Soil depth. •	Soil air contains 5 – 10 times more CO2 than the atmospheric air. •	In composition of soil air depends on the rate of production of CO2 in the soil and its removal rate. •	The CO2 produced in the soil may be diffused in to the deeper layer of soil by rain water. Mechanism of gaseous exchange in soil: Soil aeration is the mechanism of gaseous exchange in soil that prevents O2 deficiency and CO2 toxicity. The more rapidly roots and microbes use up oxygen and release CO2. The greater is the need for the exchange of gaseous between the soil and atmosphere. The exchange is facilitated by two mechanisms: a)	Mass flow b)	Diffusion a) Mass flow: Mass flow of air is much less important then diffusion in determining the total exchange that occur. It is enhanced by fluctuation in soil moisture content that force air in and out of the soil or by wind. Entry of matter into the soil, forces air out of the soil. Loss of water through evaporation or its consumption by plants provides open for air. b) Diffusion: Diffusion is the molecular transfer of gaseous through porous media. It accounts for the most of the gaseous inter change. According to this, gases in a mixture diffuse according to their individual particle pressure. (The particle pressure of the gas is the pressure through which this gas would exchange if it alone were present in the volume occupied by the mixture). Thus 21% of O2 in the air exerts a partial pressure of 0.21 atmospheres. Diffusion takes place continuously because soil air contains more CO2 and a little less O2 then the atmospheric air. Hence CO2 moves out of the soil in to the atmosphere and O2 from the atmosphere moves into the soil. Thus equilibrium is established between the gases in soil air with those in the atmosphere. The velocity of diffusion is inversely proportional to the square root of the density of gas. The density of CO2, N2, O2 and water vapor at NTP are 1.98 gm, 1.25 gm, 1.43 gm and 0.8 gm/liter. Therefore CO2 will have the slowest speed of diffusion from soil air to the atmosphere. Factors affecting composition of soil air: 	Soil compaction: Loose soil (sandy soil) has more Gaseous exchange than the compacted and tight soil. 	Soil properties: Texture, structure, amount of organic matter and moisture content affect the air exchange capacity and air permeability of the soil. 	Water logging: Pore spaces are closed under water logging condition. 	Organic matter and biological activities: Manuring increases the microbial activity which produces CO2 and increases its level. 	Cropping: Increase the amount of CO2 and reduce the O2 content of the soil. 	Season: Seasonal variations cause moisture and temperature fluctuations, gaseous exchange increase results in high O2 and low CO2 level in soil. High temperature encourages microbial decomposition of organic matter. So, high CO2 level in such soil. 1.2	What is humus? How is humus formed by the natural process? Discuss its role in nature.(2056,2059,2062,2064) Ans: With the progress of decomposition process the fresh organic matter is turned into a brown or dark brown stable organic matter called humus. Humus consists of various chains and loops of linked carbon atoms. It is an amorphous material, which is nearly insoluble in water, and fraction of it is soluble in dilute alkali (0.1 to 0.5 M NaOH or KOH) solution. The formation of humus although an exceedingly complicated biochemical process may be described in general terms rather simply. As organic tissue is incorporated into a moist warm soil it is immediately attacked by a host of soil organisms. The easily decomposed quickly succumb, first yielding intermediate substance and finally the simple soluble product humus. As decomposition occurs, two major kinds of organic compounds tend to be stabilized. First are the microbial resistance compounds of higher plant origin that have been modified by bio chemical even more resistance to microbial attack. Modified lignin compounds are most abundant, although minor amounts of oil, fats and waxes may be present second are new compounds, such as polysaccharides and polyuronides which are synthesized by micro organisms and held as part of their tissue. The modified lignins are similar materials that are partially oxidized during the decomposition, there by increasing their reactivity. The aromatic groups associated with (C) lignin’s are bounded with protein substances, there by protecting the protein from further attack. As this humic substance form side reactions occur then bind protein and other nitrogen (N) compounds as integrals part of humus complex, there by protecting the nitrogen (N) from degrading to simple inorganic forms. A wide variety of organic materials including lignins, tannins, melanins and humic acid are known to react with protein and there by protect them from microbial attack. Some nitrogen compounds are thought to react with aromatic and quinove group as well as polysaccharide. Among the reaction products are amino combinations, in which form about half the nitrogen occurs. Humus is complex and rather resistant mixture of brown or dark brown amorphous and colloidal substances modified from the original tissue or synthesized by various soil organisms. The tiny colloidal humus particles have more adsorptive capacities than those of the layered silicate minerals. The surface area of humus colloid is very high, generally exceeding that of silicate clay, so cation exchange capacity of humus far exceeds that most of silicate clay. The colloidal surface of humus are negatively charged, the source of charge being carboxylic (COOH) or phenolic (-OH) group. The extent of negative (-Ve) charge is pH dependent (high at high pH value). The water holding capacity of humus on weight basis is 4 -5 times that of silicate clay. Humus has low plasticity and cohesion which helps for its very favorable effect on aggregate formation and stability. The black Colour of humus tend to distinguish it form most of the other colloidal systems in soils. Humus is very rich in nutrient so the productivity is high. 1.3	What is soil profile? Describe the physical and chemical composition of soil. (2058, 2060) Ans: Soil profile is a vertical section through the soil, extending well into the un-weathered parent material (generally 6ft) and exposing different horizons. Examination of soil in vertical section reveals the presence of more or less distinctive horizontal layers, such a section is called profile and the individual layers are known as horizons. Every well-developed undisturbed soil has its own distinctive profile characteristic; i.e. No two soil profiles are exactly alike. The various layers comprising a soil profile are not always distinct and well defined. Often the transition from one to the other is so gradual that establishing boundaries is difficult. The upper most horizons of soil profile are darker in Colour than the lower. This difference is due to the accumulation of Organic Matter (O.M.) that result from the decay of plants roots and other organic residues incorporated into the upper soil layers. O.M. gradually decreases with depth. Soil profile is useful in classifying and surveying soils but is of greatest importance in determining how the soil can be best used. The physical composition of soil The soil consists of four major physical components; they are Inorganic materials or mineral materials, Organic matter, Water and Air. The mineral materials constitute of different soil texture like Sand, Silt and Clay. The organic matter constitute of humus. The mineral soil contains about half solid and half pore space (Water + Air). These four components occur in a thoroughly mixed condition in soils. But the air and water in a soil are extremely variable and their proportions determine in large degree the soil’s suitability for plants growth. In ideal condition the four components composition are, 1. Inorganic material or Mineral material 	-45% 2. Organic matter				- About 5% 3. Water				- About 20% to 30% 4. Air 					- About 20% to 30% The volume composition of sub-soils differs somewhat from that of top-soils. Sub-soils are lower in organic matter content, pore space and contain higher % of small pores that are filled much of time with water rather than air. The overall chemical composition of soil is inherited character from the parent material. But in soil some chemical constituent may loss by the process of evolution and may added by the process of eluviations during the profile development. The chemical components of soil The element present in soils may be solid, liquid or gaseous form. Soils are broadly non homogeneous spatially. The stoichiometry of soil is not straightforward. The ten most abundant elements of the soil are in the proportionately decreasing order as, O > Si > Al > Fe > C > Ca > K > Na > Mg > Ti Oxygen account for about 490 g/kg and silica for about 310 g/kg. Together, they account for 80 percent of the soil make up. They exist not as singular elements, O2 or Si, but combine to form minerals, some of which are listed in table. The dominant structural unit in these is the Si-O bond, which is much stronger than the typical metal-oxygen bond. The primary minerals are Quartz, feldspar, mica, amphibole, pyroxene and Olivine, which have their origin in the parent rock. The secondary minerals are those they result from weathering over time of the primary minerals (or Silicates). Climate has profound effect on the chemical and mineralogical composition of soil separates. Table: Mean element with their mass in unit soil sample SN	Element 	In Soil (mg/kg)  In Crustal 	Rock (mg/kg) 1	Oxygen 	490000	474000 2	Silica 	310000	277000 3	Alumunium 	72000	82000 4	Iron 	26000	41000 5	Carbon 	25000	480 6	Calcium	24000	41000 7	Potassium	15000	21000 8	Sodium	12000	23000 9	Magnesium	9000	23000 10	Titanium 	2900	5600 Chemical composition of common soil minerals A. Sand and silt minerals 1. Quartz or Silica 2. Feldspars a. Orthoclase b. Plagioclase c. Calcium feldspar 3. Micas a. Muscovite b. Biotite 4. Pyroxene 5. Amphibole 6. Olivine and Serpentine 7. Calcite, Magnesite, and Dolomite 8. Iron oxides a. Hematite b. Magnetite c. Limonite B. Clay minerals 1. Kaolin 2. Montmorillonite. 1.4 What are difference types of micro-organisms found in the soil and discuss the ecological importance’s.(2057) Ans: The microorganisms found in soil are soil microbes. They are in intimate contact with soil particles and cells of plant root which provide food for them. The microbes are mainly bacteria, actinomycetes, fungi, algae and soil protozoan. They play a key role in decomposition of soil. 1)	Bacteria: The bacteria are unicellular microorganisms. Bacteria are classified according to nutritional patterns and oxygen needs. Autotrophic bacteria can oxidize ammonia, nitrates, Sulphides, Sulphur, ferrous ion, Mangnes ion, hydrogen gas and carbon monoxides. The most important group of autotrophic soil bacteria is those that oxidize ammonium to nitrites and then nitrates. Heterotrophic bacteria are those that depend upon organic matter for their nutrient. Heterotrophic bacteria that do not fix nitrogen are most dominant soil bacteria and accounts for much of decomposition of organic matter. Blue green bacteria or Cyanobacteria fixes atmospheric nitrogen and release oxygen in flooded rice field. 2)	Actinomycetes: These are Gram +ve aerobic, filamentous bacteria. They have septate hyphae having cell elongated containing nucleoid body. They are also fungi like bacteria i.e. they occupy the intermediate position between bacteria and fungi in morphology. They have profusely branching body, aerial mycelium and clumpy growth in liquid culture. Their branching filamentous networks are sensitive to acidic soil. The growth of actinomycetes has the ability to attack the complex and resistant compounds like cellulose and chitin. 3)	Fungi: Fungi are organisms that live on dead or living plant or animal tissue; they have the ability to use the sun for energy. These are effective lignin decomposers. Fungi may be divided into three groups they are ascomycetes, zygomycetes, and basidiomycetes. Ascomycetes included yeast and they don’t play an important role in soil development or growth of higher plants. Zygomycetes are very important in decomposing the organic residues, molds. These are multicellular. Basidiomycete includes the fungus that bears beside (i.e. Basidospore e.g. mushroom). They help in decomposing cellulose, lignin and protein. Fungi decomposes organic residue better than bacteria. Fungi can oxidize ammonium compounds and fixed element nitrogen into combine form. 4)	Algae: Soil algae are microscopic chlorophyll bearing organism. The main group is green algae, blue green algae, yellow green algae and diatoms. Algae develop best in moist soil. Algae are not important as decomposers of organic matter but are producers of new photosynthetic growth. 5)	Soil protozoan: A protozoan is a unicellular organism without a true cell wall. Protozoa inject other bacteria, fungi and other microbes. Protozoan’s digestion of bacteria and fungi influences microbial population. The numerous protozoan found in soil help to control other minerals but also cause critical diseases. Protozoans are classified according to their method of movements. A)	Amoeba: by pseudopodia. B)	Flagellates: By whips like unit. C)	Ciliates: By hair like structure. I.e. cilia. 2.1	Define buffering and explain buffering capacity of soil. (2058) Ans: : Buffering is the capacity of resisting change in pH with the addition of acid or base. Most of soil can resist pH changes when large amount of a material either strongly acidic or basic are added. This ability of the soil to resist the change in pH is known as buffering capacity of soil. In soil, there is an exchange of ions between the soil colloid surface and in soil solution. All ions have a tendency to maintain equilibrium between the soil colloids and soil solution. This causes the reserve acidity and alkalinity for soil system that resists the measurable change in soil pH; however a small change in pH will occur when we add large amounts of acidic or basic material to soil. Buffering in soil occurs by cation exchange and neutralization of concentrated hydrogen or hydroxyl ions in soil solution. Colloid – H + NH4OH                          Colloid – NH4 + H2O. Colloid – 2H + CaCO3                         Colloid – Ca + H2CO3. The above example shows that neither the aqua’s NH3 nor the lime greatly changes the soil pH because the base is neutralized to either exchangeable NH4 or Ca++ and water. A similar buffering reaction occurs with added acids. Colloid – Ca + 2H2CO3                        Colloid – 2H + Ca (HCO3)2 (slightly basic) The dissociation H+ from carbonic acid goes on the exchange site and Ca (HCO3)2 is formed which is slightly basic. If the cation exchange capacity of soil is high, the buffering capacity of soil is also high. Soil with high proportion of silicate clays or humus has high buffering capacity. 2.2	Is cation exchange important? How does the soil resist pH changes when large amounts of a material either strongly acidic or basic are added?(2056) Ans: Cation exchange is very important phenomenon in maintaining soil quality.This process in fact is very essential in maintaining the soil pH constant even on addition of certain amount of strongly acidic or basic substance. Most of soil can resist pH changes when large amount of a material either strongly acidic or basic are added. This ability to resist the change in pH is known as buffering capacity of soil. In soil, there is an exchange of ions between the soil colloid surface and in soil solution. All ions have a tendency to maintain equilibrium between the soil colloids and soil solution. This causes the reserve acidity and alkalinity for soil system that resists the measurable change in soil pH; however a small change in pH will occur when we add large amounts of acidic or basic material to soil. Buffering in soil occurs by cation exchange and neutralization of concentrated hydrogen or hydroxyl ions in soil solution. Colloid – H+ +NH4OH                          Colloid – NH4+ + H2O. Colloid – 2H+ + CaCO3                         Colloid – Ca++ + H2CO3. The above example shows that neither the aqua’s NH3 nor the lime greatly changes the soil pH because the base is neutralized to either exchangeable NH4+ or Ca++ and water. A similar buffering reaction occurs with added acids. Colloid – Ca++ + 2H2CO3                        Colloid – 2H+ + Ca (HCO3)2 (slightly basic) The dissociation H+ from carbonic acid goes on the exchange site and Ca (HCO3)2 is formed which is slightly basic. If the cation exchange capacity of soil is high, the buffering capacity of soil is also high. Soil with high proportion of silicate clays or humus has high buffering capacity. 2.3  Major soil types of Nepal. (2055) Ans: Mainly eight types of soils are found in Nepal: Soil are formed by weathering of rocks in same place (insitu) or transported. The sand, gravel and regoliths are parent material formed by deposition. These may develop clay, silt, oxygen, plants and animals. The organisms grow and die, they become mixed in soil. In this process higher organisms develop. a)  Entisols: These are recent soils, without well developed pedogenic horizons; very common in mountainous area and recent alluvial deposits. With change in process and soil profile development the soil changes in Colour and chemical constituents. The lower part will remain somewhat same as before while upper part is mixed organic matter and minerals giving dark colored layer the A horizon. The lower unchanged layer is called the C horizon. The soils with only A and C horizons are called entisols. These are also called young soil. The parent materials are active alluvium and alluvium on shale. The texture types are loamy fine sand and ruby loam. They occur in lower Terai, susceptible mountains and middle mountains. b)    Inseptisols: In this type of soil pedogenic horizons present. This soil is more developed than entisols. The parent materials of this type soil are Alluvium on phyllate, schiest, quartizite and limestones, slate, frost shattering and colluviaction, Alluvia fan acid and neutral bedrocks, calcium rich parental material. This type of soil occurred in Terai, Siwaliks, high mountain, high Himalayas and mountain region especially central and eastern parts, lower piedment of Terai, Dun valley and middle mountains. c)  Mollisol: Mollisols are characterized by loose and dark Colour. Characteristics of grassland and evergreen forests where there is high organic matter content about more than 50 Cm. thick. The parent materials are deep alluvium aquic, udic. The texture type is silt loam with pH value 7.5. Its occurrence is in terai upper piedment. d)   Alfisols: Soils that fall in high rainfall areas, mainly of forests with A, B, C horizons. The characteristics property of alfisols is that BCSP is greater than 50%. The concentration of basic cation. The parent material is old alluvium derived from phylite. Its texture type is fine loamy to clay. Occurrence is in Siwaliks, middle mountains, high Himalayas, high mountains. e) Spodosols: The soil profile characterized by the presence of grey colored E horizon; Parent material is loamy morinal deposits. The texture type is Loam with pH value 4.7. It occurs in cold, wet climate usually under acidic coniferous forest or vegetation that develops acidic soil in high Himalayas and high mountains. f) Ultisols: The surface horizons highly leached; clay accumulation in B horizon. Its BCSP is <35% but moderate to strongly acidic. Dark surface horizon followed by E horizon. The parental material is lacustrine with the sandy loam texture having pH 5.6. It occurrence is in Siwaliks. g) Aridisols: The parent materials are Glacial and alluvial colluvial fan with texture type gravelly loamy sand with pH value 8. Its occurrence is in high Himalaya. h) Histosols: This is organic soil having more than 12% Organic carbon content. Its occurrence is in upper Narayani terraces, Jiri, Kalimati (Kathmandu) and Tansen. 2.4	Describe the important properties of humus. (2056) Ans: : With the progress of decomposition process the fresh organic matter is turned into a brown or dark brown stable organic matter called humus. Humus consists of various chains of linked carbon atoms. It is an amorphous material, which is nearly insoluble in water. The important properties of humus are: 1) The tiny colloidal humus particles are composed of C, H, O (Composition). 2)   The surface area of humus colloid is very high, generally exceeding that of silicate clay. 3)  The colloidal surface of humus are negatively charged, the source of charge being carboxylic (COOH) or phenolic (-OH) group. The extent of negative (-Ve) charge is pH dependent (high at high pH value). 4)   Although pH value, the cation exchange capacity of humus far exceeds that most of silicate clay. 5)  The water holding capacity of humus on weight basis is 4 -5 times that of silicate clay. 6)   Humus has low plasticity and cohesion which helps for its very favorable effect on aggregate formation and stability. 7)  The black Colour of humus tend to distinguish it form most of the other colloidal systems in soils .8)   Cation exchange reactions with humus are qualitatively similar to those occurring with silicate clay. Ca2+, H+, Mg+, K+, Na+ are cation with humic micelle. 9) Humus is very rich in nutrient so the productivity is high. 2.5	 Describe the different factors which play important role in soil formation.(2057) Ans: There are five different important factors that play important role in soil formation. They are-1) Parent material 2) Climate 3) Vegetation Coverage and Organisms 4) Topography 5) Time. 1)	Parent material: The structure, texture and mineral composition of rocks are the important component of the soil formation. Any one type of parent material do not always result into the development of same type of soil. The same type of rock can give rise to very different soils. E.g. Basalt (Igneous rock), give brilliant red, highly weathered soil in humid tropic and black soil in semi arid environment. 2)	Climate: Rainfall affects leaching, profile development and presence of CaCO3 layer. Excess rainfall leaches silica, basic materials that favors for the formation of hydroxide of Fe and AL. Low rainfall do not leach soluble salts as Ca, Mg and Na hence alkaline type of soil is formed if sufficient water is present. Temperature affects the effect of chemical reaction. The higher the temperature, the faster is the reaction. The rate of any chemical reaction is double for each 10°C raise in temperature warms temperature, temperature speeds of the decay and loss of organic matter due to biological activities. 3)	Vegetation Coverage and Organisms: The vegetation coverage of the land also effects the soil formation. The plants roots, growing between jointed blows and along minute fracture mineral grain, exert an expansive force tending to widen the existing openings and sometimes create new features. Insects like earthworm, snail etc and burrowing animals like rodents loosen the soil cover and create suitable for the various external agencies to have their own action on the underlying rocks that lead to weathering. 4)	Topography: The topography of the land feature is ununiform so it plays a role in soil formation. The rain water flows rapidly on steep slopes cutting the parent material on steeper slopes. Therefore soils in step slope tend to have rather shallow, poorly developed profiles. 5)	Times: It is an important factor because Soil formation requires thousands and even millions of years. 2.6	Define soil. Discuss the movement of soil water under saturated and unsaturated conditions.(2060) Ans: Soil may be defines as a dynamic natural body on the surface of the earth which composed of mineral and organic material and life form in which plants grow. The water moves from a zone of higher moisture potential to lower moisture potential. The movement of water into soil can be grouped into 1) saturated flow and 2) unsaturated flow. 1)	Saturated flow : The movement of water when the pore spaces are filled with water. The upper layers are more saturated hence the water flows downwards where the layers are less saturated. The flow of water under saturated condition is determined by two major factors the hydraulic force driving the water through soil and the case with which the soil pores permit water movement, which is expressed as: V = Kf. Where, V= Volume of water moves per unit time. K= Hydraulic conductivity of soil. F= Moving force. K depends on the size of and configuration of soil pores. This is contrast to the situation in an unsaturated soil, where hydraulic conductivity decreases with moisture. The driving force, known as hydraulic gradient is the difference in height of water above and below the soil column. The saturated flow not only occurs down profile, hydraulic force will also cause horizontal and upward flow. The gravity does not assist horizontal flow and hinders upward flow. Most of water movement likely to be saturated flow. The moves more rapidly in sandy loam than in clay loam. On the other hand horizontal movement is more evident in the clay loam. Factors affecting the hydraulic conductivity and saturated soils. •	Size and configuration of soil pores. •	Texture and structure of soil. •	Moisture content in soil pores. 2)	Unsaturated flow: Under field conditions most soil water movements occurs where the soil pores are not completely filled or saturated with water, the soil micro pores are filled with air. Further more, the irregularity of soil pores results in isolated pockets of water not in contact with each other. Water movement under these conditions is slower than in saturated conditions. At low tension levels hydraulic conductivity is higher in sandy soil than in clay. Opposite is true at higher tension levels. This relationship is to be expected since the dominance of large pores in the coarse – textured soil encourages saturated flow. Likewise the prominence of finer (Capillary) pore in the clay soil encourages more unsaturated flow than in sand. Factors affecting unsaturated flow: Unsaturated flow is governed by the same general principles affecting saturated flow i.e. its direction and rate are related to the hydraulic conductivity and to a driving force, which in this case is moisture suction gradient. This gradient is the different in tension between two adjoining soil zones. Movement will be from a zone of low tension (high metric potential) to one of high tension (low metric potential) or from a zone of thick moisture film to one where the film are thin. The force responsible for this tension is the attraction of soil solid for water. The higher the percentage of water in the moist soil, the greater is the tension gradient and the more rapid is the flow. In one case, the change from liquid to vapor states place with the soil pores. In second case, the phenomenon occurs at the land surface and the resulting vapor is lost to the atmosphere by diffusion and convection 2.7	 What is Soil profile.(2061,2062,2063,2064) Soil profile is a vertical section through the soil, extending well into the unweathered parent material and exposing all the horizons. Every soil profile has its own distinctive characteristics i.e. no two soil profiles are exactly alike .it is not always true that all these horizons are always present in each profile .A simple soil profile will usually displays five (5) distinct horizons which are :-O,A,B,C,R. 1.	‘O’ horizon :- This is the organic horizons that form above the mineral soil .they result from litter derived from dead plants & animals .They are commonly found upon the formation of organic compound. •	Oi:— organic residue are identifiable •	Oe:— organic residue are not identifiable •	Oa:- organic residue are highly decomposed 2.	‘A’ horizon:-this is the top layer of mineral soil. It consists of mixture of organic matter & mineral matter .it is further divided into A1 or A2. •	A1:—mineral horizon darkened by organic matter accumulation. •	A2:—A mineral horizon lighter colour than A1. 3.	‘B’ horizon :— this is the horizon of illuviation .small particles that have washed from O or A is accumulated in this horizon. 4.	‘C’ horizon :-it is the unconsolidated material below ‘A’ or ‘B’ horizons .it may or may not be same as the parent material from which the soil is formed .it is   affected by profile developing processes. 5.	‘R’ horizon :-this is the underlying consolidated rock .it is not affected by weathering. 3.1	Micro-nutrients and Macro-nutrients.(2057, 2060, 2063) Ans: Micro-nutrients	Macro-nutrition.
 * These are the plant nutrient needed in large amount.
 * Eg. N, P, K, Ca, Mg etc.
 * They are taken by the plants as their respective ions. Eg. Ca++, K+, NO3- etc.


 * they are supplied by means of adding fertilizers to the soil. Eg. (NH4)2, SO4 etc.	* These are the plant nutrient needed in small amount.
 * Eg. Fe, Zn, Cu, B, Cl etc.
 * They are taken by the plants as their respective ions. Eg. Fe++, Fe+++, Zn++, Cl- etc.
 * These are present in soil as the minerals.

3.2 Cation and anion exchange.(2057) Ans: Cation exchange	anion exchange Cation exchange •The total number of negative sites in the given amount of soil is called soil cation exchange capacity. •These sites gives rise to absorption of cations and these cations are replacement by other cations. • Some common soil cations are Ca2+, Mg2+, K+, Na+, Al(OH)2+, NH4+, Zn2+ etc. which are adsorb and hold by CEC sites. •Most cations are retained by the simple electrostatic attraction. Anion exchange •The total number of positive sites in the given amount of soil is called soil anion exchange capacity. •These sites gives rise to absorption of anions and these anions are replacement by other anions. •Some common soil anions are Cl -, HCO3-, CO3 2-, NO3-, SO4 2-, OH- etc. •Anions may be retained by purely electrostatic attraction and non- electrostatic process.

3.3 Calcareous and Sodic soil.(2058) Ans: Calcareous soil	Sodic soil
 * This type of soil contain greater % of salt of calcium.
 * The soil is basic in nature.
 * PH above 7.	* This type of soil contain greater percentage of sodium salts.
 * The soil is acidic in nature.
 * PH below 7.

3.5	Loam and clay.(2059) Ans: Loam	   Clay
 * Loam contains sand silt & clay.
 * To identify loam sand, silt & clay must be in equal proportion.
 * It is useful in agriculture.	* Clay contains sand & silt.
 * To identify as clay soil must contain 35-40% of clay (fire soil).
 * It is useful in pottery industries.

3.6	Molisol and Alfisol.(2060) Ans: Molisol	Alfisol Molisol •It is well developed soils with dark A horizon. •Characteristics of grass land & ever green forest. •Surface layer is soft. •The parent materials are deep alluvium aquic, udic. •The texture type is silt loam. •Its occurs in Terai upper piedment. Alfisol •It is developed in alkaline B horizon. 

• Characteristics of high rainfall area.

•Surface layer is somewhat hard. •The parent material is old alluvium derived from phylite. •Its texture type is fine loamy to clay. •Occurrence is in Siwaliks, middle mountains, high Himalayas, high mountains.

3.7	Saline and sodic soil.(2056) Ans: Saline soil	sodic soil a. Soil containing sufficient soluble salt to impair its productivity. b. It does not contain high amount of exchangeable Sodium percentage. c. Exchangeable Sodium percentage (ESP) is always less than 15 % and Sodium Absorption Ratio (SAR) is always less than 13. d. pH rang is 8.5 or belowe. Electrical Conductivity is greater than 4 decisiemens per meter (ds/m). a. Soil containing sufficient Sodium to interfere with the growth of the most crop plant. b. It contains high amount of exchangeable sodium percentage. c. Exchangeable Na percentage is always more than 15 % and Sodium Absorption Ratio (SAR) is more than 13 d. P.H range is always more than 8.5 and often rising to 10 or high.e. Electrical Conductivity is less than 4 ds/m.

3.7 Organic soil and mineral soil.(2056) Organic soil	mineral soil a. Organic soil formed from chemical decomposition & decaying of organic matter. b. Here productivity is high because of more fertility. c. Rich in carbohydrate, protein & other material. a) Mineral Soil is formed by the disintegration of the rocks or original land forms. b) Here productivity is less due to less fertility. c) Rich in phosphorous & other mineral.

3.8	Spodosol and Mollisol.(2056) Spodosol	Mollisol a. Ash Colour with reddish to black, found in A-horizon b. The soil is Acidic. c. Found in coniferous forest. d. Its parent materials are Loamy morinal deposits. e. Texture is loam. a. Dark Colour found in A-horizon. b. The soil is Alkaline. c. Found in grass land and evergreen forest. d. Its parental materials are deep colluviums on mica schiest, limestone bed rock.

e.Texture is silt loam and sandy loam

3.9	Primary and secondary mineral. (2060) Primary mineral	secondary mineral *A mineral resulting from the decomposition from primary mineral or from the precipitation of the product of decomposition.
 * Mineral that has persisted with little change in composition since they were extruded in molten lava is known as primary minerals.
 * They are most prominent in sand and silt fraction.
 * E.g. Quartz, mica, feldspar.
 * They are most prominent in clay and oxides of iron and sometime silt form.
 * E.g. Silicate clay, silt fraction

3.10	Adhesion and cohesion (2060) Ans: Adhesion	cohesion
 * Molecular attraction that holds surface of two substances in contact. (e.g. water and sand particles)
 * It holds water in surface of soil particles.	* It is the attraction of water molecules by soil molecules.


 * It is the bonding between molecules of liquid and solid.

Extra Question and their Solutions The overall chemical composition of soil is in hearted character from the parent material. But in soil some chemical constituent may loss by the process of evolution and may added by the process of eluviations during the profile development. The physical components of soil are sand, silt and clay. Sand: Sand grains may be rounded or quite irregular depending on the amounts of abrasion they have received. When not coated with clay and silt such particles are not sticky even when they are wet. They do not have any capacity to be molded (plasticity) as clay. Their water holding capacity is low, not excessive of their large size of space between the separate particles. The passage of air and water is rapid. Hence, it facilite drainage and good air movements. Silt: Silt particles are irregularly fragmental diverse in shape and seldom smooth and flat. They are micro sand particles usually Quartz is dominant mineral. The silt separate usually has an adhering film of clay posse’s stickiness (cohesion) plasticity and adsorptive capacity but much less than the clay separate itself. Silt may lead to compaction and crusting of soil surface unless it is supplemented by adequate amount of sand, clay and organic matter. Clay: Clay particles commonly are platy in shape and highly plastic when moist. When clay is wetted it tends to be sticky and is easily molded. Water tightly held on surface of soil particle is in a lower energy sate than free water. The presence of clay in a soil imparts to it a fine texture and soil water and air movement such a soil is highly plastic becomes sticky when too wet and hard and cloddy when dry unless properly handed. The chemical composition of soil Since sand and silt are dominantly quartz (SiO2), a mineral known for its resistance to weathering, these two fractions are quite inactive chemically. Even the primary mineral that may contain nutrient element in their chemical make up are generally insoluble as to make their nutrient supplying ability essentially nil. As exception to this general rule is the silt fraction of certain potassium bearing minerals such as mica, which is known to release this element at sufficiently rapid rate to meet same plant requirement. Chemically, the silicate clay vary widely kaolinite is relatively simple aluminous silicate. But the smectites, vermiculites or chlorite contain in their crystal structure varying quantities of Fe, Mg and other elements. Thydrous micas are basically potassium alumino silicate. At the surface of the silicate clays are held. Small but significant quantities of cation such as Ca+2, K+, H+, Na+ and NH4+. The cations are exchangeable and can be release for absorption by plant. In highly weathered soil, such as those in the hot humid tropic, oxides of Fe and Al are prominent if not dominant even in clay single fraction. Thus climate have profound effect on the chemical and mineralogical composition of soil separates. 1.	Entisols :-weakly developed very young soils lacking horizons & dominated by mineral matter ( eg-river banks ). A &C horizons. 2.	Inseptisols :-moderately developed soils, horizons not well developed A,B &C horizons are present ,different chemical properties, generally in humid climate .eg-brown forest soils. 3.	Mollisols :-Well developed soils with dark A horizon, high alkaline content, surface layer soft & crumbly.these are characteristics of grassland & evergreen forest where organic matter layer is greater than 50 cm thick. 4.	Alfisols(Al & Fe):-Soils with aluminium(Al) & iron (Fe) precipitation as silicates in alkaline B horizons, thin humus layer , well defined horizons. These are characteristics of high rainfall area, B50% 5.	Aridisols :- soils that remain aridy (dry) for a longer time, little humus & highly alkaline .eg.desert soils. 6.	Histosols :-Soils with considerable organic matter, carbon content more, than 12%.e.g-peats,bogs,muck. 7.	Oxisols :-well weathered tropical soils rich in iron & alminium(Al) oxides & typically rich with humus.eg-lateritic soils of tropics. 8.	Spodosols :-A1 horizon humus rich ,A2-horizon ash colour with reddish to black B horizon .It occurs mainly in cold, wet climate, acidic soils in coniferous forest. 9.	Ultisols :-Old soils found in humid climate ,surface layer highly leached ,low alkaline content ( acidic).B30% clay) mineral rich expand on wet and contract on dry ,dark in colour .eg-river,bed. In the soils that are neutral to alkaline in reaction the exchange sites are occupied primarily by the basic cations, specially Na+. soil alkanity occurs when there is a comparatively high degree of base saturation. The presence of soluble salts & Ca, Mg & Na2CO3 also gives a dominating numbers of hydroxyl ions over hydrogen (H+) ions in the soil solution .Alkaline ,soil is characteristics of Arid & semiarid regions. When salts of strong bases & weak acids such as Na2CO3,K2CO3,MgCO3 go in solution & undergoes hydrolysis is then the alkanity is developed. 2Na+ + CO3— + 2HOH ——2Na+ + H2CO3 +2OH - Since ,dissolution of NaOH is greater than of weak acid H2CO3 the OH- ion predominate the H+ ions produced by acid. The exchangeable bases such as Ca,Mg,K,Na contribute towards a reduction in acidity & increase in alkanity. The process are of great significance.eg-weathering which release these exchangeable cations from minerals & make them available for absorbtion. The addition of CaCO3 is common way for estimating nature’s supply of metallic cation.Irrigation water also contains the soluble salts, the cations are absorbed by the soil resulting in increased soil alkanity. The pH of soils of arids & semi arid regions are high because the water can’t leach all the cations since these are formed by weathering of soil minerals (rocks) so the percent (%) base saturation of these soils remains high. Soil acidity is due to H+ ions in the free form. The pH value of pure rain water is acidic near 5.6-5.7. it is because the rain water is mixed with CO2 present in atmosphere. CO2+ H2O                  H2CO3 H2CO3                 H+ + HCO3- The rain having pH of 5.6-5.7 is not acid rain. Acid rain has pH value less than 5.6. Causes of soil Acidity 1. CO2 :- CO2 causes in soil acidity since it mixed with rain water forms carbonic acid. CO2 + H2O                            H2CO3 2. Ammonium containing fertilizers :- As the plant require nitrogen, they should get nitrogen.All plants can’t fix atmospheric nitrogen & also for availability of nitrogen for plants the ammonium containing fertilizers are used which the plants can absorb.e.g – urea ( write formula) which is changed to ammonium the available form for the plants. The ammonium is oxidized by microorganisms to produce nitrate & H+ ions .When one mole of ammonium is added to soil it means addedthe two moles of H+ ions so the soil becomes acidic. 3. Sulphur oxidation :-when sulphur is oxidized it produces SO2 mixed with water leads to the formation of H+ ions & SO4. The H+ ions leads to the acidity of soil. 4. Hydrogen ion released by roots:-In taking the other cations the plant roots release H+ ions so soil because acidic .e.g in taking one mole of Ca
 * 1) Physical and chemical component of soil.
 * 1) Soil classification
 * 1) Soil Alkanity
 * 1) Factors of alkanity
 * 1) Soil Acidity

Environmental Chemistry 2.1	What are the major sources of water pollution? (2059) Ans: Any chemical, physical, biological change in water quality that has a harmful effect on living organisms and makes water unsuitable for desired uses is called polluted water. It is state of deviation from the pure condition where by its normal function and properties are affected. The major sources of water pollution are: a)	Point source: point sources are those that discharge the pollutants at specific location through pipes, ditches and sewage into the bodies of water. Example includes industries, sewage treatment plant, active and abundant mining activities, oil tankers etc. because of pointed source at specific place, they are fairly easy to identify monitor and regulate. In developing countries such discharges are largely uncontrolled. b)	Non-point source: non-point sources are those sources that can’t be traced to any single site of discharge. They are usually large land are as or air sheds that pollute water by run off or deposition from the atmosphere. Examples includes the run off of chemical in to surface water from agriculture fields, animals feed lots, urban streets, parking lots etc. Little process have been made in controlling non-point sources of water pollution because of the difficulty and expense of identifying and controlling discharge from so many diffused source. 2.2) Discuss the electrolytic technique for analyzing the sample of water. (2057)                     Ans: Electrolytic procedures require the use of carefully controlled experimental conditions to deposit an element electrolytically upon the suitable electrode. For environmental analyses of an element in the solution (water), quantitative removal on an element from solution is required. A general technique is discussed below; Electrodeposition is governed by Ohm’s law and faraday’s two laws of electrolyses. Electrolytic cell consists of two electrodes with external electrical supply. The cathode is the electrode in which metal deposition takes place due to reduction and is attached to the negative terminal of the energy source. The anode is the electrode at which oxidation takes place and is connected to the positive terminal of the energy source. Inert platinum electrodes are used for deposition and potential is controlled at which reduction of element of interest takes place. After complete deposition of metal is ensured, the electrode is dried and metal deposited is quantitatively weighed. Metals like Cd, Co, Cu, Pb, Ni, Ag, Zn, Sb etc can be determined by electrolytic analysis. The general circuit for the experiment is shown below;

2.3) What is significance of standard deviations in chemical analysis?(2058, 2062) Ans: Standard deviation is defined as the root mean square deviation of values from their mean and is calculated using formula,                     N - 1 Standard deviation is the measure of variability of analytical data. It is the measure of precision. Larger the value of standard deviation more variable is the data and less précised it is said to be. Larger value of standard deviation indicates the existence of random error and reliability of the data is low. This also implies the existence of many unassignable errors. However such data can be subjected to statistical treatment and expressed in terms of confidence interval. Even if the result has less standard deviation, it may not be an accurate one. It still may have some constant systematic error which deviates all results by same degree and data appears to be précised with less standard deviation. Therefore, less standard deviation is expected for experimenter to be reliable devoid of personal carelessness. 2.4	 Describe the principle of potentiometric titration. Or 2.5	 What information can be obtained from potentiometric titration? (2058, 2060, 2061, 2062,2063, 2064) Ans:of higher potential to the electrode of lower potential i.e. emf from higher potential electrode to lower potential electrode. The potential difference is then read directly from the instrument known as potentiometer.Potiontiometer consists of a reference electrode(whose potential does not change with concentration) which is coupled with indicator electrode whose potential changes with concentration of ions in the solution. Emf of cell which is proportional to the potential of indicator electrode can directly be read in read out. In potentiometric titration, the emf is plotted against volume of the titrant added and the point in the curve having maximum slope corresponds the equivalence point of the titration. A typical potentiometric titration is shown below. There are three types of potentiometric titration: a)	Acid base titration: A known volume of the acid to be titrated is kept in a beaker in which a standard hydrogen electrode is emerged and is connected to normal calomel electrode through a salt bridge. The hydrogen and calomel electrodes are connected to a potentiometer which records the emf of the solution. The change in emf is noted against the volume of titrant in ml. The point where the emf increases sharply gives the end point. b)	Oxidation- reduction titration: It can be carried out potentiometricaly in the same manner as acid base titration by substituting for the electrode reversible to H+ ion and inert metal such as platinum wire. The metal acts as an oxidation reduction electrode whose emf is determined by the activity ratio of the substance being oxidized or reduced and is plotted in graph. c)	Precipitation titration: in precipitation titration an electrode reversible to one of the ions involved is used such as Hg, Pb. In the titration of AgNO3 with NaCl; Ag electrode will exhibits a Sharpe change in emf. When all Ag is precipitate and a curve is obtained when plotted in graph. Fig: A typical potentiometric curve 3.1	Biological and chemical control of pests.( 2061) Ans: Biological control of pests 	chemical control of pests
 * The controlling of pest by using biological control method like by introduction of natural enemies of pest, changing cultivation practice by controlling the birth rate of pests are known as biological control.
 * It does not have any adverse effect to the surrounding.
 * It does not harm to the agro ecosystem.	* The controlling of pest by using different chemicals like DDT, Chlorinated hydro carbon, micro botany etc. are known as biological control.


 * It has any adverse effect to the surrounding.
 * It cause serious disturbance in agro ecosystem.

3.2	Density and frequency.(2062) Ans: Density	Frequency


 * Density is the number of individual of the species in any unit area.
 * * Frequency is the number of sampling unit (in %) in which particular species occurs.

3.3 Accuracy and Precision.(2062, 2064) Ans: Accuracy	Precision
 * The closeness of the observed value with true(reported) value is called accuracy
 * It is the extent to which a given measurement agrees with the standard value for that measurement.
 * It is measured as absolute and relative error.	* The degree of concordness among the results from replicate measurements is called precision
 * It is the extent to which a given set of measurement of the same sample agrees with their mean.
 * It is measured by standard deviation

3.3	Differentiate between Electrolytic and Coulometric analysis.(2056) Electrolytic analysis	Coulometric analysis
 * In electrolytic analysis the amount of analyte present is determined by converting it electrolytically to a product that is weighed as a deposit on one of the electrodes.
 * The product of electrochemical reaction needs to be weighable substance	* In coulometric analysis the amount of analyte is determined by measuring the quantity of electric charge needed to convert it completely into product.
 * The product of electrochemical reaction needs not to be weighable substance

3.5 Volumetric and Gravimetric analysis. (2055,  2056, 2057, 2059,  2060, 2063,  2064) Volumetric analysis	Gravimetric analysis
 * It deals with the measurement of the volumes of known solution which equivalently reacts with fixed amount of analyte involved in the chemical analysis.
 * Certain visual indicator has to be used to determine the end point.
 * Indicator error and observation error are the common sources of errors in volumetric analysis	*It deals with the measurement of weight of the precipitate formed by complete conversion of analyte into weighable substance
 * No visual indicator is required but instead certain specific or selective precipitating agents are used
 * Co-precipitation and weighing and drying errors are common sources of errors in gravimetric analysis

3.7	BOD and COD. (2057) BOD	COD
 * It stands for biological oxygen demand.
 * It is the amount of oxygen required for by the aerobic micro organisms for oxidizing the organic waste and nutrients in water.


 * Oxidation is done by microorganism.


 * BOD values are generally lower than the COD values.	* It stands for chemical oxygen demand.
 * It is the amounts of oxygen required by strong chemical oxidizing agents (like potassium dichromate in sulphuric acid) for oxidizing the organic wastes and nutrients in water.
 * Oxidation is done by chemical oxidizing agents.
 * COD values are generally higher than the COD values because certain organic substances which are difficult to get oxidized by common microbial oxidants can easily undergo chemical oxidation with strong oxidizing agents.

Meteorology 1.1	Define Monsoon and discuss briefly Asian Monsoon. (2057) Ans: The term monsoon is derived from an Arabic word ‘Mausim’ which means seasons or wind shifting from one direction to other. In meteorology, ‘monsoon’ means the directional shifting of wind from one direction to other. In summer, there is a warm and moist wind blowing from the ocean towards land, while during the winter, a cold and dry wind originating on land blows seaward. Monsoon circulation involves a change of 180° in direction of wind. Various theories have been purposed for the origin of monsoon, they are-: 1)	Thermal theory and  	2) planetary wind migration theory. 1)	Thermal theory: Halley purposed this theory, according to this theory, the monsoons are considered to be gigantic conventional system produced by differential seasonal heating of continental and oceanic areas. During winter the huge land mass of Asia cools more rapidly than the surrounding areas with the result that a strong high pressure center develops over the continental and the pressure over adjacent ocean is relatively low. Therefore there is an outflow of air from continental landmass towards the adjacent oceans so that it brings cold, dry air towards the low latitudes. In summer the temperature and pressure conditions are reserved. In summer the huge landmass of Asia heats quickly and develops a strong low pressure center where as pressure over the adjacent ocean is high. The warm and moist air over the ocean flows from high pressure to low pressure systems. The saturated warm and moist air is unstable and moves upward by the influence of high mountains of Asia and atmospheric turbulence. This air cools as it moves upward leading to condensation and heavy rainfall is expected. 2)	Planetary wind migration theory: Flohn purposed that the seasonal migration of the planetary wind causes the reversal in the direction of wind. Asian monsoon:                   There are two types of Asian monsoon .they are                    a) Winter monsoon       	 b) summer monsoon 1)  Winter monsoon: - During winter the intense cooling of huge land mass of Asia leads to the formation of a high pressure system over the continent. The centre of the usually strong anticyclone lies in eastern Siberia and in Peshawar in about 1035 to 1040 Mb. In the adjacent ocean are warmer than the extremely cold continent. The whole of north pacific & in the equatorial zone of Indian Ocean, there is low pressure center. Since it is summer in Australia there also is low pressure center. During the winter season, Asia is dominated by high pressure center from which there is an outflow of air that spread towards the south & southeast over Korea, China & Japan. So the continental polar air, sometimes become very steep which results in high velocity oceanic low pressure centre  termed as the winter monsoon or dry monsoon. 2) Summer monsoon: - In summer the temperature & pressure condition the Asian continent are reversed. In this season, the huge land mass of Asia heats quickly and a strong low pressure centre develops over there. This development is reinforced by inter- tropical convergence which reaches its maximum pole ward migration to a position over southern Asia. Thus, low pressure attracts warm & moist air from the ocean. It may be pointed out that the tropical air masses which are unstable and full of moisture cannot by themselves yield precipitation .precipitation results only when the moisture laden winds are forced to rise by a land form barrier or any atmospheric turbulence. 1.2 What are the applications of microclimatology in vegetated surfaces and urban areas? Explain.(2059, 2061,2060) Ans: Micrometeorology is restricted in depth to the lowest hundred meters of atmosphere from the surface boundary layer and is studies under the micro-scale. This implies that some urban scale phenomenons are studied under micrometeorology. The micro-scale phenomenon affects the plants, animals and humans. So, knowledge of micrometeorology is therefore useful in agriculture, hydrology, forestry and public health to the cities. And many of great transformation in the atmosphere take place in its lower boundary. Application of micro meteorology in vegetated surface: Meteorological parameters such as temperature, light, precipitation, relative humidity, atmospheric pressure, wind affects the plants growth and distribution. Evapotranspiration and photosynthesis are dependent on these parameters. The distribution and growth rates of vegetated species reflect climatic conditions and vegetation, in turn affects the forest on climate are greatest in the area and they are roughly proportional to the density of cover, but forest also modify the climate of adjacent areas. Widespread removal changes in species composition or compassion to other types of lands use after surface heat and water budgets and may affect regional climate. Temperature (average) within a forest (vegetated surface) is slightly lower than in adjacent open area. The greatest average difference is in summer (It may be as much as 2.0°C) and in winter it is only about 0.06°C. In a dense forest the upper canopy shades the ground and acts as primary absorbing surface during the day, then retards the temperature of soil. At night the canopy radiates heat more rapidly than the ground which is slower to cool. The same principle holds true for seasonal radiation. Depending upon the density of vegetated area up to 90% of sunlight is intercepted. The albedo of plant surface aids the control of leaf and steam temperature. Precipitations of vegetated surface areas differ from that with the adjacent areas. Rain gauze placed in open space within the forest indicates greater rainfall then outside the forest. Increased transpiration as well as evaporation of water intercepted by the vegetation reduces surpluses in water budget. Similarly vegetation increases the infiltration and reduces the stream flow from a watershed. Relative humidity is 3-10% higher within the forest then other open area, owing to the lower temperature, lighter air movement and transpiration from the plants. Evaporation from the soil is reduced due to higher humidity and if the ground is well covered with plant litter, it is reduced by 1/2 to 2/3 as compared to evaporation from soil in the open field. Surface wind speed is markedly reduced by trees. By resisting air movement, trees aid in reducing evaporation, lowering temperature and increasing relative humidity. Application of micro meteorology to the urban areas: Urban areas differ from rural areas in surface material, surface shapes and heat and moisture sources. In turn these affect radiation, visibility, temperature, wind, humidity, cloudiness and precipitation. A city with several million people and automobile and industries emits the increase level of atmospheric pollutants in the air and creates an urban aerosol which attenuates insulation. The aerosol is developed during the conditions of stable air and calms (light winds) condition. The urban aerosol reduces the isolation as well as proposition of ultraviolet radiation more than the longer wave lengths. Hence it reduces the number of bright sun sine hours as well as the horizontal visibility. Temperature normally is highest near the city center and decline gradually towards the several areas. The differences are greater at night then by day. The cars, factories, furnace lights and people in cities area generates enormous amount of heat. Tall buildings and paved streets and parking areas in cities absorb heat and obstruct cooling winds. Rainfall runs off fast, so that little standing water is available to cool the air through evaporation. This combination of effects creates an urban heat island surrounded by cooler sub urban and rural areas. The net effect of the urban aerosol or precipitation over the city and to the leeward is not clearly understood. But the proportion of precipitation in the form of snow appears to be less over urban centers (due to urban heat island) where as there is greater incidence of hail along storm paths to the lee of the urban area then over adjacent rural land. The mean relative humidity in city air is usually lower then in surrounding area. Urban surface promotes rapid run off of precipitation, where as vegetation and soil the country retain moisture for evaporation over a longer period. 1.3	 Explain the term turbulence and discuss the meteorological principles responsible for the transportation and diffusion of pollutants.( 2058, 2063, 2064) Ans: Surface wind usually undergoes rapid and irregular fluctuation in both speed and direction which indicates that the air flow has random motion with many eddies occurring near the earth surface is known as turbulence. So, turbulence is irregular motion of air over short distances in the atmosphere. Turbulent flow has many eddies occurring in the region near the earth surface. Degrees of turbulence have found to depend on a number of factors such as roughness of surface, the environmental lapse rate and speed of the winds. Mainly there are two types of turbulence. They are: 	Thermal turbulence and 	Mechanical turbulence Meteorological principles responsible for the transportation and diffusion of pollutants: Air quality at a given site varies tremendously from day to day even though emission may remain relatively constant. The determining factors have to do with the weather; how strong are the winds, in what direction are they bowings, what is the temperature profile, how much sunlight is available and how long has it been since the strong winds or the precipitation were able to clear the air. Thus, transport and diffusion of air pollutant depends on the dynamics of the atmosphere. Stable air discourages the dispersion and dilution of pollutants stability of atmosphere is largely determined by the rate of change of air temperature with altitude. Rapid vertical mixing takes place when air is unstable that encourage pollution dispersal. Wind plays major role for the transportation and diffusion of pollutants. The gaseous waste or smoke is taken away or diluted by wind. The stronger the wind greater will be the dilution of pollutant. Similarly, during thermal inversion atmosphere is stable so the pollutant dispersion is minimum. Plume model and diffusion of pollutants: The atmospheric temperature profile affects the dispersion of pollutants from a smokestack. Plume refers to the path and extent in atmosphere of the gases effluent release from a source. There are six types of plume behavior which determine the diffusion level of pollutants. Coning: Coning occur when atmosphere is neutrally stable. Its shape is symmetrical and cone like. It occurs with vertical temperature gradient which is sub adiabatic. Looping: Looping occurs when the atmosphere is very unstable and there is rapid vertical air movement, both up and down. The high degree of turbulence helps in dispersing the pollutants rapidly. Here vertical temperature is super adiabatic. Fanning: Fanning occurs when a stable atmosphere greatly restricts the dispersion of the plume in the vertical direction it occurs when temperature gradient is positive so it spreads only horizontally. Lofting: Lofting occurs when an inversion exists only below the plume and plume is inhibited from mixing downward and mixing in the upward direction is uninhibited. Such lofting helps to keep the pollution high above the ground. Fumigation: Fumigation occurs when plume is under an inversion layer, emission move downward much more easily than upward. Trapping: Trapping occurs when plume is caught between inversions and can only diffuse within a limited vertical height. The lofting plume is the most favorable with respect to minimizing air pollution. The fumigation and trapping plumes are very critical from the point of ground level pollutants concentration.

1.4	Discuss the applications of micrometeorology for the betterment of urban areas and human welfare.(2059, 2060, 2061) Ans:

Ans: Micrometeorology is restricted in depth to the lowest hundred meters of atmosphere from the surface boundary layer and is studies under the micro-scale. This implies that some urban scale phenomenons are studied under micrometeorology. The micro-scale phenomenon affects the plants, animals and humans. So, knowledge of micrometeorology is therefore useful in agriculture, hydrology, forestry and public health to the cities. And many of great transformation in the atmosphere take place in its lower boundary. Application of micro meteorology to the urban areas: Urban areas differ from rural areas in surface material, surface shapes and heat and moisture sources. In turn these affect radiation, visibility, temperature, wind, humidity, cloudiness and precipitation. A city with several million people and automobile and industries emits the increase level of atmospheric pollutants in the air and creates an urban aerosol which attenuates insulation. The aerosol is developed during the conditions of stable air and calms (light winds) condition. The urban aerosol reduces the isolation as well as proposition of ultraviolet radiation more than the longer wave lengths. Hence it reduces the number of bright sun sine hours as well as the horizontal visibility. Temperature normally is highest near the city center and decline gradually towards the several areas. The differences are greater at night then by day. The cars, factories, furnace lights and people in cities area generates enormous amount of heat. Tall buildings and paved streets and parking areas in cities absorb heat and obstruct cooling winds. Rainfall runs off fast, so that little standing water is available to cool the air through evaporation. This combination of effects creates an urban heat island surrounded by cooler sub urban and rural areas. The net effect of the urban aerosol or precipitation over the city and to the leeward is not clearly understood. But the proportion of precipitation in the form of snow appears to be less over urban centers (due to urban heat island) where as there is greater incidence of hail along storm paths to the lee of the urban area then over adjacent rural land. The mean relative humidity in city air is usually lower then in surrounding area. Urban surface promotes rapid run off of precipitation, where as vegetation and soil the country retain moisture for evaporation over a longer period. Application of micro meteorology for the welfare of human beings: Human health, energy and comfort are affected more by climate then by any other element of the physical environment. Physiological functions of the human body respond to changes in the weather and the incidence of certain diseases varies with climate and seasons. Of all life forms, humans are the most adaptable to varying atmospheric conditions. Among the climatic element that affects the human body, the more important are temperature, sunshine and humidity. Wind exerts an influence largely through its effects on skin temperature and body moisture; the circulatory, respiratory and nervous system resists changes in atmospheric temperature, pressure. Extreme temperature is the most common causes of illness related to weather. Heat stroke or hyper thermo develops when the body is unable to maintain its heat balance at high relative humidity and air temperature above that of body. Atmospheric pressure and relative humidity changes appear to bear a relation to certain kinds of pains specially those associated with respiratory infection and muscular aches. Nutrition requirement in hot climate differ from those in cold climate. Under cold condition, the body requires a greater food intake to maintain heat. Application of micro meteorology for the welfare of animals: Domestic animals are highly dependent on climatic factors that affect pasture or feeding crops. Fluctuation in animal product frequently results from variation in the feed supply rather than from the direct effects of climatic elements or the animals. All breeds have optimum ranges of climate for maximum growth and development. The climatic elements which affect livestock directly are temperature, light, precipitation, relative humidity, atmospheric pressure, wind and storm and which effect indirectly through feed supply and those which influence plant growth or the spread of insects and diseases. High temperature generally reduces production and reproductive capacity. For e.g. dairy cow produce less milk when exposed to high temperature; the optimum is about 10°C. Hen lays larger eggs in winter. Sunlight and the duration of day light influence animals in several ways. Fertility is affected by daylight, especially in poultry. (Commercial poultry farmers commonly supply light to increase egg production). The primary influence of precipitation on livestock is through its effects on feed. Very dry air i.e. low relative humidity may cause discomfort, winds and high temperature also cause to increase the water requirements of animals. 1.5 Define pollution. Describe how air pollution is affected by meteorological parameters.(2055, 2062) Ans: Any addition to environmental components (air, water etc.) that threatens the health survival and activities of humans and other living organisms is called pollution. Pollutants can enter to the environment from natural as well as anthropogenic activities. Effects of meteorological parameter on air pollution: The meteorological parameters that affect the atmospheric pollutants can be grouped under two categories they are: primary parameters and secondary parameters. The wind speed turbulence is under primary parameters where as temperature, humidity, precipitation, solar radiation, pressure, visibilities are the secondary parameters. The primary parameters are responsible for dispersion and dilution of pollutants where as secondary parameter affect the primary parameters. Even though the discharge of contaminants into the atmosphere in a given area remains constant the degree of air pollution may vary from day to day because of difference in meteorological conditions. The important meteorological parameters that influence air pollution are: 1) Wind: The direction and speed of surface wind govern in drift and diffusion of air pollutants discharge near the ground level. The higher the wind speed at or near the point of discharge of pollution, more rapidly are the pollutants carried away from the source. Then the pollutant so dispersed will not exist at the same concentration but will rapidly be diluted with greater volume of air. 2) Atmospheric stability and temperature: During temperature inversion the atmosphere is stable and very little turbulence or mixing takes place. The accumulation of smoke and other contaminants prevents the sun rays to warm the ground and adjacent air. Fog is commonly associated with the inversion because the temperature of the air at ground level falls below the dew point of the water vapor in the air. 3) Mixing height: It can be defined as the height above the earth surface to which related pollutants will extend through the action of atmospheric turbulence. It is usually related to wind direction, wind speed and wind turbulence. 4) Rainfall: It exerts decreasing action on the pollutant discharge into the atmosphere. It accelerate the deposition of particulate matter on the ground and hence its removal from the atmosphere and goes to the ground. It also helps to remove the concentration of gases pollutants which are soluble in water. 5) Humidity: The moisture content of the atmosphere influences the corrosive action of the air pollutant and indicates the potentiality for fog formation in relation to the degree of air pollution. 6) Solar radiation: Depending on the location, solar radiation can have an effect on the type and rate of chemical reaction in the atmosphere. 2.1 Why yields of rice are consistently less in equatorial regions then in temperate regions? (2056) Ans: Although there is high solar input in the equatorial regions than the temperate regions but the yield of rice is consistently less. This may be due to following regions. a) In general, high temperatures (high water stress) require that the plant expands more of its gross production energy in respiration. Thus it costs more to maintain the plant structure in hot climates. b) In equatorial regions the length of day is shorter than in the temperate regions. The longer the length of day, more solar radiation is converted into chemical energy during photosynthesis. So there is large accumulation of organic matter (i.e. energy once in this case) in temperate regions than in the equatorial regions having comparatively shorter wavelength. 2.2	Discuss how the atmosphere maintains earth’s heat level.(2056) Ans: Our atmosphere has many layers. When the heat rays entered to the layers they are found to have short wave length so they can penetrate the atmospheric layer and then reach to the earth surface. Now in the earth surface, these rays are trapped and the wavelength increases. Some rays are trapped & some are reflected. The reflected wave have longer wavelength, they could not penetrate and escape out from the earth atmosphere and hence green house effect is observed. Due to this green house effect, the heat of the earth’s atmosphere is maintained. If there is not such effect then, there would be extreme hot at the day time & extreme cold at night. The temperature difference becomes very high. Thus, by the help of this green house effect, atmosphere maintains earth’s heat level. 2.3 Describe the role of meteorological parameters in the environment.(2060) Ans: Influence of meteorological parameters is the greatest extent during the transport and diffusion of air pollutants. The motions of the atmosphere which may be highly variable are responsible for transport and diffusion of air pollutant. Winds carry pollutants away from single source and produce leeward plume that experience a progressive decrease in intensity of pollution. Precipitation reduces the air pollutant by washout effect. Pollutants on air are removed by rain, diluted by wind and unstable air. The meteorological parameters that effect the atmospheric pollutants can be grouped under two categories are primary parameters and secondary parameters. The wind speed, direction and the atmospheric turbulence are under primary meteorological parameter, whereas temperature, precipitation, humidity, solar radiation, pressure, visibility are the secondary parameters. The primary parameters are responsible for dispersion and dilution of pollutants where as secondary parameters affects the primary parameters. a)	Wind direction: It represents the direction of travel of the pollutants. b)	Wind speed: Wind speed effects the pollutants by two ways, first wind speed determine the travel time from a source to given receptor and second effect of dilution in down wind direction. The concentration of air pollutant is inversely proportional to the square of speed of wind. c)	Turbulence: It is induced by stability of atmosphere when the earth surface is heated by the solar radiation the lower layer of the atmosphere becomes unstable and the thermal turbulence becomes greater under condition of light winds. In clear night with light wind, heat is radiated from earth surface resulting in the cooling of the atmosphere near the earth surface. Under this condition the turbulence is minimum. Similarly, temperature, pressure, humidity, pressure, insolation, precipitation, visibility are the secondary parameters which influence the air pollutants. 2.4 Discuss the role of anthropogenic gases for climatic change.(2057) Ans: Since the creation of earth a great change in climate has been reported. Climate is the most variable aspect of natural environment. It varies all time, scale and in different amplitude. The role of anthropogenic gases for climatic change:- A natural effect that traps heat in the atmosphere near the earth’s surface is termed as green house effect. Some of the heat flowing back toward space from the earth’s surface is observed by water vapor, carbon monoxide, ozone, and several other gases in the atmosphere and then radiated back towards the earth’s surface. If the atmospheric concentrations of these green house gases rise, the adverse temperature of the lower atmosphere will gradually increases. The following are the major gases for climate change: a) Carbon dioxide (CO2): CO2 is released by volcanoes, Oceans, decaying matter, combustion of fossil fuel. Concentration of carbon dioxide in atmosphere increases due to anthropogenic factors. Combustion of fossil fuel amounts for over 80% of fossil fuel CO2 emission. In 1985 CO2 concentration was around 315 ppm and growing rate was 1ppm per year. By 1994 it had reached 358 ppm and was doubling at about 1.6 ppm per year. CO2 concentration is now almost 30% higher than they were just before the industrial revolution. b)  Methane (CH4): Methane is another naturally occurring gas that is increasing in concentration as a result of human activities. it is produced by bacterial fermentation under anaerobic condition such as occurs in swamps, marshes, rice, paddies and land fills from fossils, fossil fuel combustion from livestock. CH4 concentration is currently increasing at about 1.4% annually. c) Nitrous oxide (N2O): Nitrous oxide (laughing gas) is another naturally occurring gas that is increasing due to human activities. The current atmospheric concentration is about 312 ppb. The growth of N2O is estimated at about 0.2% per year. The major source of atmospheric N2O is nitrification process of nitrogen fertilizer. d)  Chlorofloro carbon: Halocarbons are carbon based molecules that have chlorine, fluorine or bromine in them. Halocarbons are potent green house gases. There is no natural source of halocarbons but presently they exist in the atmosphere from the foam production, refrigerants, and air conditioning device and aerosol proponents. They are environmentally important not only because they contribute to global warming but also because chlorine and bromine atoms that find their way into the stratosphere have ability to destroy ozone catalytically. 2.5 Discuss the causes of ozone layer depletion.(2055,2058) Ans: Ozone is compound containing 3– atom of Oxygen and is the important species in the stratosphere, acting as a productive radiation shield for living organisms on the earth. The maximum ozone concentration is around 10 PPM in the stratosphere at the altitude of 25 – 30 Km. It is produced by a photo chemical reaction. O2 + hµ (242nm)                       O + O O + O2 + M                           O3 + M. (Increased energy) Ozone absorbs ultraviolet light very strongly in the region 220 – 330 nm. About 90% of the ozone is found in the stratosphere between roughly 10 and 50 Km. is commonly referred to as ozone layer. Scientist discovered that the ozone layer was being attacked by CFCs, chemicals used in refrigerator, air condition system, cleaning solvent and aerosol spray. When the CFCs are released into the atmosphere, Chlorine containing chemicals are raised and are broken down by sunlight. The chlorine reacts and destroys ozone molecules up to 10000 per CFCs molecule. The destruction of the ozone reduces the thickness of the ozone layer and hole is formed. This hole is known as ozone hole. 2.6	What are the major sources of air pollution? Explain.(2060) Ans: Any addition to environmental components (air, water etc.) that threatens the health survival and activities of humans or other living organism is called pollution and that undesired change in air is called air pollution. There are two major sources of air pollution; a) Natural source and b) Anthropogenic source. a) Natural source includes : 1)	Dust and other forms of suspended particulate matter form due to storms. 2)	Sulphur oxide and particulate matter form volcanoes. 3)	CO2, NO2 and particulate from forest trees. 4)	Hydrocarbon and pollen grains from living plants. 5)	Methane and hydrogen sulphide from decaying plants. 6)	Salt particulate form the sea. 7)	Moist natural source of air pollution is volcanic eruption and some forest fire, rarely reach harmful level. b) Anthropogenic source includes: 1)	Emission of CO2, NO2, CO particulate from transportation. 2)	Agriculture burning and man made fire emitting CO2, CO, particulate matters etc. 3)	Burning of fossil fuels in power plants and industries releasing hazardous wastes, NO2, SO2 etc. 4)	Nuclear power plants releasing radioactive substances and mining activities releasing suspended particulates. 5) Solid waste disposal process which emits CO2, NO2, CO, SO2 etc. 2.7 Describe the effects of global warming in the environment.(2055,2059, 2063) Ans: The consequences of global warming are serious threat to the people and existing ecosystem and species. Some places would get dry and some place wet, the consequences of global warming in future are as follows: Food production: Food productivity could vary considerably increasing in some areas and dropping in others, because of change in the global distribution of heat and precipitation. Water is the limiting factor in the growth of many crops, especially in dried areas. Computer models have projected drops in the global yield of key food crops ranging from 30% to 70%. Forest and biodiversity: Rapid climate change would have severed impact on natural ecosystems. Forest growth in temperate and sub artic region would move toward the poles or to higher altitudes, if the forest could keep up with the rate of climate change. Large scale forest die backs would also cause mass extinction of species that could not migrate to new areas. Any sifts in regional climate could threaten many parks, wildlife reserves, wilderness areas, wetlands and coral reefs. And fish would die due to temperature increases in lakes and streams. Human health and weather extremes: A warmer world would affect human health by disrupting supplies of food and fresh water, displacing millions of people and altering disease patterns in dangerous and in predictable ways. The spread of tropical climates from the equator would bring malaria, encephalitis, yellow fever, danger fever, and other insect born disease to formerly temperate zones. In warmer world weather extremes, such as prolong heat waves and droughts, would become common in many areas. Sea level rise: Water expands as it warms, decreasing its density and increasing its volume, which causes sea level to rise. In addition, melting glacier and ice caps contribute to increasing ocean volume and rising sea level. Since 1900 the world’s average sea level has raised 10-20 Cm. and now appears to be rising about 2.5 decades. Warming at the poles caused ice sheets and glaciers to melt even particles. The global sea level would rise even more. About one third of the population and more than a third of the worlds economics infrastructure are concentrated in coastal region are highly affected by global warming. Scientist project that even a modest 0.3 meter (1-Foot) rise in average sea level would 2.8	Positive and negative impact of green house effect. Or 2.9	What are the consequences of green house phenomenon?(2061) Ans: Green house effect is a natural effect of the atmosphere that trap heat near the earth’s surface. Green house effect is possible only due to presence of green house gases which are -: CO2, CH4, N2O, CFCs, waqter vapour etc. Due to the green house effect living things are present in the earth biosphere. Due to presence of green house gases in the atmosphere fluctuation of temperature during day and night is minimum. This minimum fluctuation in temperature causes the survival of living beings. But due to the increase of atmospheric concentration of these gases the average temperature of the lower atmosphere is going to increase which cause the loss of agricultural production, loss of biodiversity, weather extremes and sea level rise. 2.10	 What do you understand by El Nino? Write its major effect.(2062) Ans: Under normal condition the water of the eastern pacific of equators, Peru and northern Chili are surprisingly as cold as 10°C, than the normal value of water. This part of eastern pacific is teeming with fish, since there cold water is rich in nutrients. But once every 5-10 years from December to March, the water of the eastern pacific warms up a little (4°c higher than normal values) when disrupts the up willing of cold water. This in turn disrupts the anchovy fishery key to Peruvian economy. This phenomenon is called El Niño. El Niño is not a regular event as it takes place once every five years on the average. But when it occurs, the local environment suffers from enormous disruption. The anchovy fish die for shortage of food. This has disastrous affect on Peruvian economy. Normally, trade wind blowing the equator from the south east pacific toward west pushes warm water out of the sea. When El Nino comes along these trade winds become weak and change direction from west to east i.e. the warm pacific current starts to flow east. When it reaches the South America coast, it kills cold water fishes. The warm water also warms the air, which lowers the atmospheric pressure and spark torrential storms along Chili coast reaching as far as southern California thus change the rainfall pattern due to weak low pressure and leads to extensive drought and heavy floods in the other parts of the world. 2.11Discuss the structure of the atmosphere with neat diagram and explain how ELNino affect monsoon.(2056) Ans: Trosphere: is the basal part of the atmosphere which is about upto 20Km. above the earth surface is known as Troposphere. For living organism this is the most important zone of atmosphere. The important events, such as cloud formation, lighteneig, thundering, thunder strome formation etc. all takes place in trosphere. Stratosphere: Next to troposphere, the second zone of about 30 Km. height, is called Stratosphere, where the temperature values shows an increase up to 90oC. This increase in temperature is due to ozone formation under the influence of ultra violet component of sunlight. Upper layer of stratosphere form stratopause. Mesosphere: About 40 Km. in height, the zone, next to stratosphere, is called mesosphere. In this zone, temperature shows again a decrease up to- 80oC. Upper layer of this zone are mesosphere. Ionosphere: The rest above the mesosphere, upto the height of above 300 Km. above the earth’s surface is iionosphere. Most of the gaseous components which become ionized under the influence of radiant energy, remains as ions. Due to their much less density, they are rarely present in the molecular form. Fig : Layers of Atmosphere

3.1 Weather and climate.(2055,2059) Weather	climate
 * It is the day to day state of the atmosphere.
 * It denotes the short term variations of atmosphere in term of temperature, pressure, wind, moisture, cloudiness, precipitation and visibility.
 * It is highly variable, constantly changing from hour to hour or from day to day.
 * Weather is the differentiation of climate.	* It is the state of atmosphere acting over an extended period of time.
 * It denotes the atmospheric status in terms of acting over an extended period of time.


 * It remains more or less constant with slight variations.
 * Climate is the integration of the weather.

3.2	El Niño and western disturbances.(2055) El Niño	western disturbances
 * This is sudden raise of temperature in sea water in December (about 4-6 c)
 * Lower aquatic animals are highly affected and higher are some what affected.	* This is not sudden raise of temperature.


 * Lower aquatic animal as well as higher are equally affected.

3.3	Biosphere and Lithosphere.(2057) Biosphere	Lithosphere
 * This is the sphere consisting of that part of lithosphere, atmosphere and hydrosphere where living organism lives.
 * It covers three huge layers; lithosphere is the part of it.	* This is the sphere consisting of soil and earth crust.


 * It is the smallest layer as it is a part of biosphere.

3.4 Diffusion and inversion.(2057) Diffusion	Inversion
 * Here movement of pollutants from higher concentration to lower concentration.
 * Diffusion decreases atmospheric pollution.	* Here temperature of upper layer of the atmosphere is greater then lower.
 * Inversion increases the atmospheric pollution.

3.4	Solar radiation and Terrestrial radiation.(2057) Solar radiation	Terrestrial radiation
 * It is the emission of light rays from sun.
 * Sun itself a source of energy.


 * It involves only one step.	* It is the loss of heat from the earth surface.
 * Here the radiation is re radiated by the earth surface.
 * It involves two steps.

3.5	Specific humidity and relative humidity.(2058) Specific humidity	Relative humidity
 * It is the weight of water vapor per volume of air.
 * It is expressed as gram of water vapor per cubic meter of air.
 * It is seldom used in meteorology.  	* It is the weight of water vapor per weight of given mass of air including water vapor.
 * It is expressed as gram of vapor per kg of air.


 * It is more frequently used in meteorology.

3.7 Primary and secondary pollutants.(2060,2063) Primary pollutants	secondary pollutants
 * They are the pollutant which are release directly in to the air in a harmful form.
 * Primary particulates that are released from fires, industrial process, and volcano eruption or from sandstorms are some of the primary pollutant.	* The pollutant which reach to the air after the interaction with other agent.
 * Photochemical oxidant smog and atmospheric acids are the most important secondary pollutants.

3.8	Subsidence Inversion and Trade wind Inversion (2060) Subsidence Inversion	Trade wind Inversion
 * A subsidence inversion forms in an air mass when a large body of air subsides and spreads out above a lower layer. In the process the air heats dynamically more in the upper portion that at its base.
 * This inversion may develop at considerable altitudes and are common in the region of trade winds and in large slow moving high pressure area.	* It is a type of subsidence inversion which is results of process of subsidence in adiabatic heating and low relative humidity.


 * Trade wind inversion tends to restrict vertical cloud development, thus dries the land surface. It occurs in trade wind areas.

3.9	Coriolis force and frictional force (2060) Coriolis force	Frictional force
 * It is a force that influences on wind direction of the earth because of the earth rotation. However it is not considered as force and it is effect of resulting from rotational movement of the earth and the movement of air.
 * It causes all wind in the north hemisphere to move towards their rights and those of the south to move left.	* It is a force that produces from friction of two or more materials or molecules. It tends to reduce the velocity of the winds.


 * The effects of frictional force depends on the pressure gradient of the air.

3.10	Monsoon and El Nino.(2063) Monsoon	El Nino
 * The directional shifting of wind from one season to other is called the monsoon. Monsoon greatly affect climate of Asia.

* At the interval of 5-10 years from December to march, temperature of the eastern pacific ocean increased by 40C from the normal temperature this event is called El Nino.
 * Monsoon circulation involves a change 1800 in direction of wind.
 * During El Nino, the area of warm water expands eastward and the area of coverage and precipitation drift eastward. rainfall increases over eastern pacific ocean and along the west coast of south America.

3.11	Monsoon and ENSO.(2063) El Nino	ENSO
 * At the interval of 5-10 years from December to march, temperature of the eastern pacific ocean increased by 40C from the normal temperature this event is called El Nino.
 * During El Nino, the area of warm water expands eastward and the area of coverage and precipitation drift eastward. rainfall increases over eastern pacific ocean and along the west coast of south America.	* ENSO is the combine form of El Nino and southern oscillation.


 * ENSO events lasts for 12 months from December to December . the event mostly imparts for Peruvian anchovies.

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Narayan Thapaliya Piyush Khanal Ganga Sapkota Uttam Aryal

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Edited By:- Man Kumar Dhamala (M.Sc T.U Environmental Science) Prakash Chandra Aryal (M.Sc. T.U Environmental Science) Madan Krishna Suwal  (M.Sc.T.U Environmental Science) Bhoj Raj Neupane (M.Sc.T.U Environmental Science) Bishal Rizal (M.Sc.T.U Environmental Science) Bed Prasad Bhurtel (M.Sc.T.U Environmental Science) Hem raj K.C. (M.Sc. T.U Chemistry) Ratna Chudamani Neupane (B.E.)

Edition:-First, 2064

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