What are the two basic requirements for gas exchange. I know they are ventilation and perfusion, but are they any simpler words?

What do all macromolecules have in common with each other? oa. they all are formed from the same elements. ob. they all have major roles in cell membranesoc. they all act as catalysts in the body. od. they all have peptide bonds between carbon atoms.

Based on the topographic map of mt. st. helens, what is the contour interval of the volcano about height is 2,950 m?

Which process takes place last in the human being which process takes place last in the development of a human being