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Quiz Chapter 3: Movement of Substances Across the Plasma Membrane

10 questions · Form 4 Biology Bab 3: Movement of Substances Across the Plasma Membrane

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Full Question List & Answer Key

Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.

1. 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.
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Answer: B

Salt draws water out of bacterial micro-organisms by osmosis due to the hypertonic environment, inhibiting bacterial metabolic growth.

2. 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
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Answer: B

Carrier proteins bind specific solute molecules like glucose and change shape to transport them across the membrane during facilitated diffusion.

3. A farmer applied excessive amounts of chemical fertilizer around crop roots. Soon after, the crops wilted. What explains this?

  1. A. The soil solution became hypotonic, causing root cells to burst.
  2. B. The soil solution became hypertonic, drawing water out of root cells via osmosis.
  3. C. Fertilizer blocked stomata, preventing transpiration.
  4. D. Fertilizer caused rapid active transport of toxins into leaves.
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Answer: B

Excess fertilizer turns soil water hypertonic relative to root cell sap, causing water to leave root cells by osmosis and resulting in plasmolysis and wilting.

4. 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.
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Answer: A

Cholesterol stabilizes the membrane at higher temperatures by restraining phospholipid movement, preventing the membrane from becoming excessively fluid.

5. 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
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Answer: B

Glycoproteins (and glycolipids) act as cellular markers, receptors, and recognition sites on the outer plasma membrane.

6. Which molecule acts as a membrane stabilizer by regulating membrane fluidity at varying temperatures?

  1. A. Glycolipid
  2. B. Carrier protein
  3. C. Cholesterol
  4. D. Ribosome
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Answer: C

Cholesterol molecules interspersed within the phospholipid bilayer regulate membrane stability and fluidity.

7. According to the Fluid Mosaic Model, which part of the phospholipid molecule is hydrophilic?

  1. A. Fatty acid tail
  2. B. Phosphate head
  3. C. Cholesterol ring
  4. D. Glycoprotein chain
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Answer: B

The phosphate head of a phospholipid is polar and hydrophilic (water-loving), interacting directly with aqueous environments.

8. Plasmolyzed plant cells can regain turgidity if placed back into distilled water. What is this recovery process called?

  1. A. Hemolysis
  2. B. Crenation
  3. C. Deplasmolysis
  4. D. Active diffusion
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Answer: C

Deplasmolysis occurs when a plasmolyzed plant cell absorbs water in a hypotonic medium, restoring turgor pressure.

9. Which of the following substances can pass through the phospholipid bilayer directly via simple diffusion?

  1. A. Glucose
  2. B. Fatty acids
  3. C. Sodium ions (Na+)
  4. D. Amino acids
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Answer: B

Fatty acids are non-polar and lipid-soluble, allowing them to dissolve and pass directly through the hydrophobic phospholipid bilayer.

10. 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
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Answer: C

In a hypertonic solution, water leaves red blood cells by osmosis, causing them to shrink and undergo crenation.

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