The Anatomy and Physiology of Animals/Plasma Membrane Worksheet/Worksheet Answers
Correct answers in italics.
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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