Answer: they have to maintain homeostasis, so they remove waste to do so..
Answer:
Enzyme
Explanation:
Enzymes are the bio-catalyst that serve to accelerate the metabolic reactions occurring in a living cell. All the metabolic reactions of organisms are catalyzed by enzymes. Each metabolic reaction is catalyzed by specific enzyme. Absence of that particular enzyme leads to absence of the respective product. Since genes code for protein which regulate the specific trait, absence of enzyme does not allow the expression of that trait.
Example: Absence of enzymes for chlorophyll synthesis would lead to absence of chlorophyll from leaves of the green plants.
If reproduction didn't exist, all species would eventually go extinct.
The fact that species are becoming immune through natural selection being passed down generations
The central nervous system of the frog is different from that of humans; if the optic nerve of a frog is cut, the animal will be able to see again within weeks but the same damage in humans would cause permanent blindness :).
