The fact that oxygen and carbon dioxide move easily through cell membranes is due to

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.

Explain how scientists use geologic time to determine the age of landforms.

Vessels draining the myocardium of the heart, open primarily ,into which chamber?