A change in an organisms that increases fitness
What is it called?

Is it considered muscle s ennervation if sympathetic fibers innervate the vessels within the muscle?

What are the four basic classes of organic molecules how do they differ structurally and functionally

Animal bodies (and even plant bodies for that matter) are complex enough that life couldn't exist without enzymes. enzymes are usually large, complex biological catalysts that are expensive to make. enzymes speed up the rate of chemical reactions without being used up during the reaction (they can be reused many times). they are highly specific in the reactions they regulate. knowing what enzymes are and how they function, why does this explain why complex life forms could not exist if there were no enzymes.