Biological membranes are composed of fluid phospholipid bilayers that form closed cellular compartments. Proteins embedded in the lipid core of the membrane maintain internal cellular environments by selectively controlling the movement of molecules across the lipid bilayers.

Please answer the following questions:

1. Summarize the functions of membrane proteins.

2. The net movement of a substance down its concentration gradient from a region of greater concentration to one of lower concentration is called

A. Osmosis.

B. Diffusion.

C. Co-transport.

D. transport

3. Cells will swell when placed in a(an):

A. Isotonic Solution.

B. Hipertonic solution.

C. Hipotonic solution.

4. Junctions that permit the transfer of water, ions, and molecules between adjacent plant cells are _____.

A. Tight junctions.

B. Adhering Junctions.

C. Desmosomes.

D. Gap junctions

5. Larger molecules, particles of food and small cells are moved into or out of cells by exocytosis and endocytosis. Explain the process of phagocytosis.