Is the cell wall the only feature which really seperates the Plant Kingdom from the Animal Kingdom? While at first you think this silly. You think all plants make food (sugars) from sunlight, but this is not true for primitive plants, such as fungi.
And, some animals look like plants - such as undersea life and slime molds. (And then, there’s another oddity - the Venus Flytrap.) In fact, I think the slime mold is still debated by biologists as to which Kingdom it belongs.
Anyway, I was just wondering. The cell wall of plant cells is the only distinguishing trait I could think of that might define the fine line between plant and animal.
Fungi are not “primitive plants.” Comparison of DNA has shown that fungi are more closely related to animals than plants. Their cell walls are made of chitin (yup, same stuff that insects use). Cell walls of plants are made of cellulose. Bacteria also have cell walls, which are mostly peptidoglycan. They also are neither plants nor animals. Recent taxonomic systems recognize three Domains (Bacteria, Archaea and Eukarya). Eukarya includes the Kingdoms for Plants, Fungi, Animals and Protists (“stuff we can’t put in any other category”).
Besides cell walls, plants have chloroplasts. I believe that all plants are autotrophs and all animals and fungi are heterotrophs. The other stuff can be either.
No, as I was taught there are only two Kingdoms of life…until we conclusively meet E.T.s, that is! Fungi are within the Plant Kingdom, to the best of my knowledge.
Fungi aren’t plants, they belong to the fungi kingdom (ruled over by the benevolent mushroom king). IIRC all plants photosynthesize. Slime mould isn’t a plant, fungus or animal it belongs to the protista kingdom.
Hmm…me posted too soon? Maybe there’s been breakthrough thinking since I was in a Biology class? Based on SparrowHawk’s post, maybe scientists have re-classified things since the 1980’s?
E-gads! Are the 1980’s that outdated already? :eek: - Jinx
I took my first college-level biology course in 1985 and they were already teaching the Five Kingdom system at that point :). Indeed it was pointed out at the time that some reaerchers had come up with as many as 20-odd kingdoms, depending on various interpretations of the available taxonomic data ( most of the splits were off of the Protista - as Sparrowhawk noted a bit of a ‘garbage-can’ group ).
Fungi are rather odd in being defined by a unique suite of characters, rather than any unique character per se. But plants they’re not.
IIRC.
Plants have chloroplasts and cell walls. They under go Photosynthesis and Cellular Respiration.
Animals have mitochondrians and only under go Cellular resperation.
Oh yeah, and plants are green.
No, all eukaryotes have mitochondria, and some non-plants photosynthesize.
I think the OP is really asking two questions: (1) What is a plant, and (2) What is an animal? Otherwise, it’s like saying, “What separates a zebra from a snake?” How can you answer, other than by saying, here is what defines a zebra, and here is what defines a snake.
SparrowHawk has already answered the “What defines a plant?” question. Regarding animals, I remember that they all have Hox genes, but I’ll defer to someone who knows more to explain what those are or why they’re so important.
This is correct. In the complex Radiata (radially-symmetric animals: Ctenophores and Cnidarians), 2 or 3 individual Hox genes may be present (Porifera - the sponges - have been found to also possess one primordial Hox gene). However, only in the Bilateria (bilaterally-symmetric animals: just about everything else) do we find the Hox cluster - a suite of Hox genes (between 7 and 13) working together to determine morphological development. It is this cluster which defines “head”, “tail” and “trunk” for bilateral animals (and controls various aspects of limb development, etc. - for those who have them - as well).
