Quiz Chapter 3: Movement of Substances Across the Plasma Membrane

1. Which component on the extracellular surface of the plasma membrane serves as a recognition site or receptor?

1. A. Hydrophobic tail
2. B. Glycoprotein
3. C. Cholesterol
4. D. Contractile vacuole

2. How does salting preserve fresh fish against bacterial spoilage?

1. A. High salt levels destroy bacterial DNA directly.
2. B. High salt creates a hypertonic environment, dehydrating bacterial cells via crenation/plasmolysis.
3. C. Salt acts as an enzyme inhibitor in fish muscle tissue.
4. D. Salt increases water potential in the fish tissue.

3. The sodium-potassium pump transports 3 Na+ ions out of the cell and 2 K+ ions into the cell. What type of transport is this?

1. A. Simple diffusion
2. B. Osmosis
3. C. Facilitated diffusion
4. D. Active transport

4. Why do red blood cells burst (undergo hemolysis) in distilled water, whereas plant cells do not?

1. A. Plant cells possess a rigid cell wall made of cellulose.
2. B. Plant cells do not absorb water via osmosis.
3. C. Animal cell membranes are completely impermeable to water.
4. D. Plant vacuoles pump water out as fast as it enters.

5. Which of the following molecules moves across membranes via active transport during mineral absorption in plant roots?

1. A. Nitrate ions moving from low soil concentration into root cells
2. B. Carbon dioxide diffusing into stomata
3. C. Water entering root hair cells
4. D. Oxygen diffusing into root cells

6. What happens to the rate of facilitated diffusion when all available transport proteins become fully saturated with solute molecules?

1. A. The rate drops to zero immediately.
2. B. The rate reaches a maximum limit (Vmax) and levels off.
3. C. The rate increases exponentially.
4. D. Active transport takes over automatically.

7. Which characteristic prevents sodium ions (Na+) from passing directly through the hydrophobic core of the phospholipid bilayer?

1. A. They are lipid-soluble.
2. B. They are small and uncharged.
3. C. They are charged polar ions.
4. D. They are non-polar organic molecules.

8. If the plasma membrane lost all its cholesterol molecules, how would its physical properties change at elevated body temperatures?

1. A. It would become overly fluid, unstable, and overly permeable.
2. B. It would become completely rigid and freeze solid.
3. C. It would prevent all water molecules from passing through.
4. D. It would automatically convert into a single cell wall layer.

9. When red blood cells are placed in a 5% sodium chloride (hypertonic) solution, what phenomenon occurs?

1. A. Hemolysis
2. B. Plasmolysis
3. C. Crenation
4. D. Deplasmolysis

10. Which protein type undergoes a conformational structural change to transport glucose molecules down their concentration gradient?

1. A. Channel protein
2. B. Carrier protein
3. C. Glycoprotein
4. D. Peripheral protein