AS Level Biology chapter 4: Cell membranes and transport MCQs with answers

By Team Megalecture · Updated 4 Nov 2026

25 exam-style questions on Cell membranes and transport, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.

25 questions · 2 topics · 10 per test

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What chapter 4 covers

Ten Cell membranes and transport questions with answers

Try each one, then open the answer. These ten stay the same; the test draws new ones every time.

1. A hormone travels in the blood to every part of the body but only some cells respond to it. Why?

  1. A
    the hormone is broken down by enzymes in all cells except the target cells
  2. B
    only target cells have receptors with a shape that is complementary to the hormone
  3. C
    the hormone can only pass through the membranes of target cells
  4. D
    only target cells receive a blood supply that carries the hormone
Show answer

Answer: B. Responding requires a specific receptor. Cells without a complementary receptor are exposed to the hormone but do not respond.

2. Which statement describes a channel protein?

  1. A
    it binds hormones on the outer surface and starts a signal in the cell
  2. B
    it has a water-filled pore through which specific ions can diffuse
  3. C
    it acts as an antigen that identifies the cell to the immune system
  4. D
    it changes shape to move molecules against a concentration gradient using ATP
Show answer

Answer: B. Channel proteins have a hydrophilic pore for ions; movement is passive. Changing shape to move a molecule is how carrier proteins work.

3. What is one role of cholesterol in a cell surface membrane?

  1. A
    it acts as a receptor that binds hormones and starts a response in the cell
  2. B
    it forms channels through the bilayer that allow ions to pass through
  3. C
    it provides the ATP needed for active transport across the membrane
  4. D
    it helps regulate membrane fluidity and reduces its permeability to ions
Show answer

Answer: D. Cholesterol stops the membrane becoming too fluid when warm or too rigid when cold, and it helps block ions and water-soluble molecules.

4. What is the surface area to volume ratio of a cube with sides of 3 cm?

  1. A
    3 : 1
  2. B
    1 : 2
  3. C
    6 : 1
  4. D
    2 : 1
Show answer

Answer: D. Surface area = 6 × 3 × 3 = 54 cm2; volume = 3 × 3 × 3 = 27 cm3. 54 : 27 = 2 : 1.

5. Cubes of agar containing an indicator, with sides 1 cm, 2 cm and 4 cm, are placed in acid. Which cube changes colour completely first, and why?

  1. A
    all at the same time, because the rate of diffusion is the same for every cube
  2. B
    the 4 cm cube, because it has the largest total surface area for uptake
  3. C
    the 2 cm cube, because its surface area is neither too large nor too small
  4. D
    the 1 cm cube, as it has the largest surface area to volume ratio
Show answer

Answer: D. The 1 cm cube has an SA : V of 6 : 1 and the shortest distance to its centre. The larger cube has more total surface but far more volume to fill.

6. What is the water potential of pure water at atmospheric pressure?

  1. A
    0 kPa
  2. B
    100 kPa
  3. C
    −100 kPa
  4. D
    it depends on the temperature only
Show answer

Answer: A. Pure water has the highest possible water potential, defined as zero. Adding solutes makes it negative.

7. A spherical cell grows until its radius has doubled. What happens to its surface area to volume ratio?

  1. A
    it doubles
  2. B
    it stays the same
  3. C
    it falls to one quarter
  4. D
    it halves
Show answer

Answer: D. For a sphere, SA : V = 4πr2 : (4/3)πr3 = 3/r. Doubling r halves the ratio; surface area rises four times but volume eight times.

8. Why do phospholipids form a bilayer in cell membranes?

  1. A
    hydrophobic heads face the water while the hydrophilic tails face inwards
  2. B
    hydrophilic heads face the water and hydrophobic tails face inwards
  3. C
    the phosphate heads form covalent bonds with each other across the bilayer
  4. D
    the tails form hydrogen bonds with water molecules on both surfaces
Show answer

Answer: B. The polar heads interact with water inside and outside the cell, while the non-polar tails cluster together away from water.

9. Where are the carbohydrate chains of glycoproteins and glycolipids found in a cell surface membrane?

  1. A
    embedded in the hydrophobic core, between the fatty acid tails
  2. B
    on the inner surface, projecting into the cytoplasm of the cell
  3. C
    on the outer surface, facing outside the cell
  4. D
    sandwiched between the two phospholipid layers, next to the tails
Show answer

Answer: C. Carbohydrate chains project from the outer surface, where they can act as receptors and antigens.

10. Visking tubing containing concentrated sucrose solution is placed in a beaker of distilled water. After an hour the tubing is heavier. Why?

  1. A
    water moved in by osmosis, from higher to lower water potential
  2. B
    water was pumped in by active transport through the tubing
  3. C
    the tubing absorbed water like a sponge and expanded
  4. D
    water moved in by osmosis, from lower to higher water potential
Show answer

Answer: A. Visking tubing is partially permeable: water crosses it but sucrose cannot. Water moves by osmosis from the distilled water (higher water potential) into the sucrose solution (lower), so the tubing gains mass.

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Cell membranes and transport: questions students ask

How many Cell membranes and transport MCQs are there?

25, each with the answer and a short explanation, across 2 topics: Fluid mosaic membranes, Movement into and out of cells. Every chapter test draws ten of them, so you can take it many times.

Is the AS Level Biology chapter 4 test free?

Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.

How is the chapter test marked?

The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.

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