Plasma Membrane Worksheet Answers

1. The two most important functions of the plasma membrane are two of:
 * 1. The plasma membrane defines and encloses the cell;
 * 2. It is the boundary between intra and extracellular fluid;
 * 3. It is selectively permeable i.e. it maintains homeostasis.

2. The best definition of Homeostasis is:


 * a) Keeping a constant temperature inside a cell or organism despite external changes.


 * b) Keeping constant conditions within a cell or organism despite external changes.


 * c) Keeping a constant pH inside a cell or organism despite external changes.


 * d) Keeping constant conditions outside a cell or organism despite internal changes.

3. The two most abundant molecules in the plasma membrane are:
 * 1. Proteins
 * 2. Phospholipids (or fats or lipids)

4. This is true of the structure of the plasma membrane:


 * a) It is a double layer of protein molecules with phospholipid molecules randomly dotted through it
 * b) It is single layer of phospholipid molecules
 * c) It is a double layer of phospholipid molecules with protein molecules dotted in it.
 * d) It is single layer of protein molecules with phospholipids dotted in it.

5. Add the following labels to the diagram of the plasma membrane shown below.


 * protein molecules; protein channel; double layer of phospholipid molecules



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