Interactions Between Cells and the Extracellular Environment

1. The rate of diffusion is dependent on which factors?
a. temperature of the solution
b. the permeability of the plasma membrane to the
diffusing substance
c. concentration differences across the two sides of the membrane
d. a and b
*e. all of the above

2. What statement for osmosis is NOT true?
a. the simple diffusion of solvent (water) through a membrane
more permeable to the solvent than to the solute
b. osmosis depends on a difference in total solute concentration
*c. osmosis depends on the chemical nature of the solute
d. none of the above

3. In passive transport what type of energy is required?
*a. No energy required, passive transport is the net movement of molecules and ions across a membrane from higher to lower concentration.
b. ATP
c. Osmosis
d. both b and c.

4. What fibers have been likened to reinforcing iron bars in concrete?
a. Collagen
b. Integrins
c. Elastins
*d. Collagens and Elastins

5. A membrane which allows some molecules to pass into or out of a cell is?
a. Carrier Mediated Transport
*b. Selectively Permeable Transport
c. Passive Transport
d. Facilitated Diffusion
e. None of the Above

6. Why are the Sodium-Potassium Pumps in cells so important?
a. The extra sodium Na+ is used for "coupled transport" of other molecules.
b. Sodium and Potassium are 2 of the electrolytes in the body and are essential for the nerves, and muscles.
c. The active pumping of the sodium out of the cell prevents cell damage or from causing the cell to burst.
*d. All the above
e. none of the above

7. What would be an example of a semipermeable membrane
a. a plastic bag
*b pantyhose
c.glass
d a plastic bucket
e. b & c

8. In what kind of solution will a RBC swell and possibly burst?
a. hypertonic solution
b. hypo-osmotic
c. isotonic solution
*d. hypotonic solution

9. The chemical driving force for a substance crossing a cell membrane,
*a. depends only on the concentration gradient, regardless of whether or not the substance is an ion.
b. depends only on the concentration gradient if the substance is uncharged, but also depends on the electrical force if the substance is an ion.
c. is the total driving force on the substance, even if it is an ion.
d. is the force that pushes molecules across the membrane, but only if the substance is actively transported.
e. always favors movement of a molecule into the cell.

10. The osmotic pressure of a solution depends on
*a. the concentrations of all solute particles contained in it.
b. the concentrations of all permeant solute particles contained in it.
c. the concentrations of all impermeant solute particles contained in it.
d. pressure exerted on the solution by the atmosphere.

11. What do pumps and carriers have in common?
a. They both transport molecules up electrochemical gradients.
b. They both transport molecules down the electrochemical gradients.
c. They both transport lipid-soluble substances preferentially.
d. They both utilize ATP to transport molecules
*e. They both are specific to certain molecules.

12. The movement of water across a plasma membrane occurs by
a. an active transport water pump.
b. a facilitated diffusion carrier.
*c. simple diffusion through membrane channels.
d. all of these.