Why is it that animals cannot do a set of solid-waste-free metabolisms? plants' metabolism always dump gas at the very most......
what about that type of species which is animal in nature, but has chlorophyls? (sorry, I've been away from Biology materials, so I don't know if that's amoeba, volvox or whatever......)
there known as oddities of nature neither plant nor animal, that’s what the kingdom Protista is for this half and half critters.
Animals move actively and they do not, in principle, change shape. Moving requires much more energy than the immobile life of plants, this more metabolism. At the same time, retaining the same shape neccesitates the excretion of waste products. In principle, a plant just adds all metabolic products (except some gasses) to its organism, growing and changing shape, occasionally shedding parts of its "body" (leaves etc.). I bet you look differently on your wooden desk now Please Register or Log in to view the hidden image! Hans
Hmmm.... I can accept that...... Still, it's rather odd that (though luckily this doesn't happen) these post metabolism matters are not reproduced into more useful organic substances...... (good though, just think what if animals keep changing their outer skins......)
Oh, oneother question: If animals were to be fed with nutritions only (ie, only carbohydrates, fat, protein, vitamin etc etc etc without the food which contains them), would they stop making solid-waste?
yes, they have the leftover, non-digested parts of the meat left over. also, around 60% of the mass of your daily crap is bacteria, so we don't give off as much actual solid waste as most people think. Most of it is still alive, and it's directly from us.
that's why playing with poop is a Bad ThingTM . one other thing I thought of: Even non-meat-eating plant give off 'solid' waste- it's just in a soluable form. If you ever water plants with hard water (high in minerals), and in particular water high in salt, the plant will, over time, develop a whitish covering on it's leaves. That's the solidified salt from the water it drank and then excreted. It pooped out the salt during transpiration, but because of the weight of the salt molecule, it stuck to the leave while the water molecules evaporated away.
Just so you all know what it is you're talking about ... "Human fecal material consists primarily of bile pigments, mucus, unabsorbed minerals, undigested fats, cellulose, meat protein toxins, peeled off cells, potassium chloride, sodium bicarbonate, and water . Fecal composition is approximately three-fourths water (50 to 150 ml) and one-fourth solid matter." :m: Please Register or Log in to view the hidden image! :m:
Well, the feces excreted by animals represents that material, mostly, that they did not want to absorb into their bodies in the first place. If we consider the waste products of cellular metabolism, the main waste products are carbon dioxide and water. Plants release these into the air as gases, or use some of that "metabolic water" for their own purposes. A human, for example, will get rid of the carbon dioxide in the same form for the most part. The metabolic water can be conserved for use, or if in excess, removed from the blood by the kidneys. I think that maybe your question is related to different fates of the products of nitrogen metabolism in plants vs animals. Again, considering a human vs a plant; A human is unable to store any significant amount of the protein that they consume. Excess amino acids cannot just be stored the way that one can store excess fat or glucose. So, your liver (mostly) takes the excess amino acids ( and nucleotides and any nitrogenous substance for that matter) and cuts off the amino group. This makes ammonia, which is very toxic. So, the ammonia is made into urea, which is nice and water soluble. Your kidneys can remove the urea and dump it out in the urine. One of the main reasons to pee is to get rid of this excess nitrogen, mostly in the form of urea. Birds and reptiles get rid of most of their excess nitrogen as uric acid, a solid. This is a way to conserve water. Uric acid is much of that white stuff in bird poop But, plants can't pee. I once read an interesting essay on this topic titled "Why Trees Don't Urinate On Dogs". They do have to deal with excess nitrogen and ammonia, but they can't easily excrete it. So, they attach it to carbon compounds and hold onto it in some form that won't cause them any metabolic problems. This is why plants have such interesting nitrogen compounds, all of those amines (e.g. caffeine, nicotine, morphine, cocaine, quinine, etc). Some plants have come up with amines that serve their purposes very well. Amines, being basic, typically taste bitter, a way to discourage animals from eating them. Other amines might make an animal sick, or give it hallucinations. Still other amines kill or inhibit the growth of microbes, a way of warding off parasites. This is why so many medicinal substances come from plants. Hope this helps. Chuck
to river-wind: Maybe I need to go to beaches to see the proof Please Register or Log in to view the hidden image! Please Register or Log in to view the hidden image! Please Register or Log in to view the hidden image! to chuck: Interesting. So it means that plants have auto anti-toxic metabolisms, isn't it?
