you know my parents are always telling me, the right person is going to come along. Then why do we have to go through all the wrong people??

Which of the following systems in absorbing oxygen and releases carbon dioxide

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.

What was the land like over 500 million years ago? what was under the sea?