5. Air pressure is caused by the mass of the air being pulled down by the over a particular object or the surface.

Which of the following describe the role a biochemical pump plays in active transport? a it prevents water from moving across the cell membrane. b it uses energy to move materials across the cell membrane against the concentration gradient. c it large molecules cross the cell membrane without using energy. d it a cell move molecules from an area of higher concentration to an area of lower concentration.