Wikipedia:Reference desk/Archives/Science/2022 June 6

= June 6 =

Etiology of feline hepatic lipidosis
I’ve noticed that there is very little known about what causes feline diseases, in this particular case, feline hepatic lipidosis. What are the current trends, hypotheses, and theories about this disease in cats? Viriditas (talk) 02:15, 6 June 2022 (UTC)
 * I'm afraid I don't have a veterinary background, but it seems to me from that article that the immediate trigger in most cases is pretty well-understood: prolonged fasting. Lack of food intake requires the body to pull from its fat reserves. An aspect of this is that the liver will carry out gluconeogenesis to convert fatty acids from the blood to glucose, to maintain a minimum blood glucose level and prevent hypoglycemia. This is not specific to cats; it's a feature of all vertebrate physiology. However it looks like the cat liver has issues with this, and so fat deposits build up in the liver and cause liver damage and eventual failure. This seems to me to share features with fatty liver in other species including humans. Felids are hypercarnivores adapted to an all-carnivorous diet, and I'm betting the liver's reduced capacity to handle prolonged fasting has something to do with that. If you want more in-depth stuff you're going to have to take a look at some feline veterinary books or journals. --47.147.118.55 (talk) 07:11, 10 June 2022 (UTC)

respiration and oxygen
If plant respiration uses oxygen, why do plants release O2 into the atmosphere? Is it just that photosynthesis produces more oxygen than the plant can use? And do fungi also take oxygen from the atmosphere or soil gases? (I assume they do, since most are aerobic.) — kwami (talk) 04:03, 6 June 2022 (UTC)
 * Because in very simple terms, they use the energy from Photosynthesis, to split water, H2O, and Carbon dioxide, CO2, and recombine them to produce Carbohydrates and other organic compounds, HnCn+otherstuff, and Oxygen gas, O2. The complex process may also use atmospheric O2 (see Photorespiration and Cellular respiration), but overall more O2 is created. The organics are what they build their physical material with, the surplus oxygen is a waste product. The Photosynthesis article says all this in its lede paragraph.
 * When Cyanobacteria first began using photosynthesis and similar processes (Green algae and their Plant descendents arrived a little later, see Evolutionary history of plants), resulting in the Great Oxidation Event, the extra oxygen they produced was toxic to almost all other living things on Earth and (it is thought) caused an Extinction event called the Oxygen catastrophe: eventually, Anaerobic organisms evolved the ability to tolerate increasing levels of oxygen, and then to use it. {The poster formerly known as 87.81.230.195} 90.199.171.123 (talk) 05:24, 6 June 2022 (UTC)
 * Yes, the lead says that, but poorly. Where it says that oxygen is also released as a waste product that stores three times more chemical energy than the carbohydrates, the obvious question is why the plant doesn't retain all that stored energy. So I take it that the O2 is surplus to need, with no good way for the individual plant to store it. (Or no need to store it, since enough is available in the atmosphere and soil.)
 * O2 will leave the plant very quickly. The O2 or the waste product is undoubtedly too difficult to store or to convert to energy on demand, unlike sugar. Abductive  (reasoning) 07:00, 6 June 2022 (UTC)
 * And what of fungi? I assume that, having mitochondria, they share the basic cellular respiration of plants and animals. How do they get that oxygen? Is it passively absorbed from the environment, or is there something more active? And do they 'exhale' CO2 as a waste product? Do plants also exhale CO2, or do they manage to use what they produce?
 * Fungi respire. The issue in observing it is the low rate of metabolism in organisms that are not producing their own heat. The bubbles in beer are from yeast respiring. Plants must generate CO2 when they metabolize sugar, but they will grab it right back if they are photosynthesizing. Plants usually are CO2-limited, not energy-limited. Abductive  (reasoning) 07:00, 6 June 2022 (UTC)
 * It's a bit difficult to work out which organisms do what from the main articles, because it's not clear if an article doesn't say because it's complicated or because it's simple. — kwami (talk) 05:43, 6 June 2022 (UTC)
 * Nearly all protists, plants, animals and fungi respire, and need oxygen to do so. The few exceptions prove the rule. Since plants produce their own oxygen, I'm told that they don't need oxygen from the air, but they do need oxygen. Abductive  (reasoning) 07:00, 6 June 2022 (UTC)
 * Thanks. That helps. — kwami (talk) 07:25, 6 June 2022 (UTC)
 * Concerning oxygen is also released as a waste product that stores three times more chemical energy than the carbohydrates, I've just removed that statement from photosynthesis. See that article's talk page. IpseCustos (talk) 00:10, 8 June 2022 (UTC)

As for why the plant doesn't keep the waste oxygen which represents so much energy, oxygen is very reactive. And thus damaging to cells. Mitochondria exist to isolate the oxygen using reactions from the rest of the cell. --User:Khajidha (talk) (contributions) 14:19, 6 June 2022 (UTC)
 * To clarify a possible ambiguity, u|Khajidha, I think you mean "oxygen-using reactions"; correct? {The poster formerly known as 87.81.230.1965} 90.199.171.123 (talk) 07:34, 7 June 2022 (UTC)
 * Whoops. Yep. --User:Khajidha (talk) (contributions) 09:18, 7 June 2022 (UTC)
 * When making 1 kilogramme of carbohydrates, a plant produces about 1 kilogramme of oxygen, and when burning that kilogramme of carbohydrates, it consumes the same amount of oxygen. A plant only intends to burn a small fraction of the carbohydrates it makes. A large fraction is meant as structural material (wood consists of carbohydrates), which is not intended to burn. Best to get rid of the oxygen, or the wood might ignite to easily. Anyway, there's no way a one tonne tree can store one tonne of oxygen at standard pressure and temperature, as oxygen is a gas. PiusImpavidus (talk) 07:46, 7 June 2022 (UTC)