How does blood return back to the heart given the low venous blood pressure?

Which layer will become saturated first when rain falls?

Which statement best explains why cells were observed in more detail using a compound microscope than a simple microscope? a compound microscope has greater magnification ability than a simple microscope. the compound microscope was invented before the simple microscope. a compound microscope is much easier to manufacture than a simple microscope. compound microscopes were more common than simple microscopes.

How does a catalyst influence a chemical reaction?