AP Biology Study Guide Name____________________ Per __
Read chapter 8 in Campbell.
selectively permeable osmotic concentration
osmotic potential hypertonic
plasma membrane fluid-mosaic model
permease membrane channel
facilitated diffusion electrostatic gradient
electrochemical gradient receptor
membrane pump active transport
sodium-potassium pump endocytosis
Answer the following questions:
1. Describe the process of osmosis and explain the relationship between osmosis and
diffusion. How is the net movement of water through a membrane in osmosis related to the
concentration of solute molecules?
2. Define the terms hypotonic, hypertonic, and isotonic. Explain what would happen to an
animal cell and a plant cell placed in a hypertonic medium and to an animal cell and a plant
cell placed in a hypotonic medium.
3. Construct a diagram and describe the fluid-mosaic model of the cell membrane. In your
description, point out the phospholipid molecules, and indicate the hydrophobic and
hydrophilic portions; point out the proteins that span the interior of the membrane and those
that are confined to the surface; indicate the role of the cholesterol molecules, and explain
why lateral movement of molecules within the membrane is possible. List substances to
which the membrane is relatively permeable, and those to which it is relatively
4. Describe the role that permeases (proteins) play in moving material through membranes.
5. Construct a diagram and explain how an electrochemical gradient can be generated across
a membrane and what is meant by an electrochemical gradient.
6. Distinguish between simple diffusion, facilitated diffusion, and active transport. Indicate the
role of these processes in the life of the cell.
7. Using diagrams, describe the processes of endocytosis, phagocytosis, pinocytosis, and
exocytosis, explaining the role of these processes in transporting substances into and out of
8. Explain the concept of water potential and its importance to plant cells.