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Quiz Chapter 3: Movement of Substances Across the Plasma Membrane

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

Question 1 of 10Score: 0

What is the primary difference between passive transport and active transport?

Full Question List & Answer Key

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

1. What is the primary difference between passive transport and active transport?

  1. A. Passive transport moves substances against a concentration gradient using ATP.
  2. B. Active transport requires ATP energy to move substances against a concentration gradient.
  3. C. Passive transport relies exclusively on carrier proteins.
  4. D. Active transport only allows the transport of water molecules.
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Answer: B

Active transport requires metabolic energy (ATP) to move molecules against their concentration gradient.

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. 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.

4. 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.

5. 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.
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Answer: C

Charged ions cannot cross the non-polar hydrophobic tail region of the lipid bilayer and require specific channel or carrier proteins.

6. Intravenous saline drips given to hospital patients usually contain 0.9% NaCl solution. What is the osmotic status of this solution relative to human blood plasma?

  1. A. Hypertonic
  2. B. Hypotonic
  3. C. Isotonic
  4. D. Saturated
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Answer: C

A 0.9% NaCl solution is isotonic to human blood plasma, ensuring red blood cells maintain normal osmotic balance without shrinking or bursting.

7. 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.

8. 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.

9. 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
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Answer: D

The sodium-potassium pump moves ions against their respective concentration gradients using ATP energy, which defines active transport.

10. 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
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Answer: A

Root cells absorb mineral ions (e.g., nitrates) against a concentration gradient from the soil via active transport requiring ATP.

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