5 Written Questions

1. The charge difference between a cell's cytoplasm and the extracellular fluid, due to the differential distribution of ions. Membrane potential affects the activity of excitable cells and the transmembrane movement of all charged substances.
2. The regulation of solute and water concentrations in body fluids by organisms living in hyperosmotic, hypoosmotic, and terrestrial environments.
3. In comparing two solutions, referring to the one with a lower solute concentration.
4. The diffusion of water across a selectively permeable membrane.
5. The spontaneous passage of molecules and ions, bound to specific carrier proteins, across a biological membrane down their concentration gradients.

5 Matching Questions

1. pinocytosis
2. electrogenic pump
3. tonicity
4. aquaporin
5. isotonic

1. a An ion transport protein that generates voltage across a membrane.
2. b Having the same solute concentration as another solution.
3. c A transport protein in the plasma membrane of a plant or animal cell that specifically facilitates the diffusion of water across the membrane (osmosis).
4. d A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes.
5. e The ability of a solution to cause a cell within it to gain or lose water.

5 Multiple Choice Questions

1. In comparing two solutions, referring to the one with a greater solute concentration.
   1. hypotonic
   2. hypertonic
   3. isotonic
   4. exocytosis
2. A protein covalently attached to a carbohydrate.
   1. aquaporin
   2. glycolipid
   3. glycoprotein
   4. hypotonic
3. A lipid covalently attached to a carbohydrate.
   1. plasmolysis
   2. glycolipid
   3. flaccid
   4. glycoprotein
4. Protein channel in a cell membrane that allows passage of a specific ion down its concentration gradient.
   1. gated channel
   2. ion channel
   3. tonicity
   4. ligand
5. The movement of specific molecules into a cell by the inward budding of membranous vesicles containing proteins with receptor sites specific to the molecules being taken in; enables a cell to acquire bulk quantities of specific substances.
   1. pinocytosis
   2. receptor-mediated endocytosis
   3. phagocytosis
   4. endocytosis

5 True/False Questions

1. electrochemical gradient → The diffusion gradient of an ion, representing a type of potential energy that accounts for both the concentration difference of the ion across a membrane and its tendency to move relative to the membrane potential.

   True        False

2. fluid mosaic model → The currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of individually inserted protein molecules drifting laterally in a fluid bilayer of phospholipids.

   True        False

3. selective permeability → A property of biological membranes that allows some substances to cross more easily than others.

   True        False

4. proton pump → Having the same solute concentration as another solution.

   True        False

5. concentration gradient → An increase or decrease in the density of a chemical substance in an area. Cells often maintain concentration gradients of ions across their membranes. When a gradient exists, the ions or other chemical substances involved tend to move from where they are more concentrated to where they are less concentrated.

   True        False