Lesson 3.2.3.2

3.2.3.2 Diffusion, osmosis and active transport Quiz: AQA Biology, Unit 2

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.2.3.2, Diffusion, osmosis and active transport: 20 multiple choice questions for the AQA Biology (7402), Unit 2: Cells, written with Revision Ninja.

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The 20 questions

  1. Which process moves water molecules across a partially permeable membrane from a region of higher water potential to lower water potential?

    • Osmosis
    • Facilitated diffusion of glucose
    • Active transport
    • Co-transport

  2. Which process requires hydrolysis of ATP to move a substance against its concentration gradient?

    • Active transport
    • Osmosis
    • Facilitated diffusion
    • Simple diffusion

  3. Which process uses carrier proteins to absorb sodium ions and glucose together into cells lining the ileum?

    • Hydrolysis of lipids in micelles
    • Osmosis
    • Simple diffusion
    • Co-transport

  4. What is the main limitation of simple diffusion across the phospholipid bilayer?

    • It allows large polar molecules to pass through rapidly by ATP.
    • It only allows water to pass through the channel proteins.
    • It allows only small, non-polar molecules to pass through easily.
    • It requires carrier proteins for all molecules, including oxygen.

  5. In facilitated diffusion, what is the role of a channel protein?

    • It binds glucose and uses sodium ions to move it into the cell.
    • It hydrolyses ATP to pump ions against the concentration gradient.
    • It changes the shape of the phospholipid heads to allow diffusion.
    • It forms a pore that allows specific ions or polar molecules to diffuse down a gradient.

  6. A plant tissue cell has a water potential of -300 kPa and the solution outside has -500 kPa. Which direction does water move?

    • Out of the cell, from -300 kPa to the solution at -500 kPa.
    • No net movement, because both values are negative.
    • Into the cell, from the solution at -500 kPa to the cell at -300 kPa.
    • Into the cell, because active transport always moves water inwards.

  7. Which of these explains why active transport needs carrier proteins?

    • Carriers bind the substance and change shape to move it against the gradient.
    • Carriers are needed only for osmosis and not for any other process.
    • Carriers hydrolyse glucose into water and carbon dioxide during transport.
    • Carriers form permanent channels for water to diffuse down a gradient.

  8. A cell has a higher concentration of solutes than its surroundings. What happens to net water movement by osmosis?

    • Water moves into the cell, because the cell has a higher water potential.
    • Water moves into the cell, because the cell has a lower water potential.
    • Water moves out of the cell, because the cell has a higher water potential.
    • There is no net movement of water, because solute concentration does not affect osmosis.

  9. Which factor would increase the rate of facilitated diffusion across a membrane?

    • A reduced number of carrier proteins in the membrane.
    • A smaller concentration gradient across the membrane.
    • A greater number of channel proteins in the membrane.
    • A smaller surface area of the membrane available for diffusion.

  10. Glucose enters an epithelial cell of the ileum against its concentration gradient. Which process is most likely responsible?

    • Osmosis through aquaporin channels in the membrane.
    • Facilitated diffusion through a glucose channel protein alone.
    • Co-transport, driven by the sodium ion gradient.
    • Simple diffusion through the phospholipid bilayer.

  11. A dilution series of sucrose solution is used with plant tissue to identify water potential. What is the water potential of the tissue when there is no net gain or loss of mass?

    • The same as the solution in which there is no change in mass.
    • Lower than all the solutions, because the tissue absorbs all the water.
    • Twice the water potential of the most concentrated solution.
    • Zero kPa, because the tissue has no solutes at all.

  12. Which statement about active transport and facilitated diffusion is correct?

    • Both processes move substances down a gradient and both require ATP hydrolysis.
    • Facilitated diffusion moves substances against a gradient using ATP, while active transport moves them down it.
    • Both processes move substances against a gradient and neither uses carrier proteins.
    • Facilitated diffusion moves substances down a gradient without energy, while active transport moves them against it using ATP.

  13. A cell is exposed to a poison that blocks ATP production. Which transport process would be most directly stopped?

    • Simple diffusion of oxygen across the cell membrane.
    • Facilitated diffusion of glucose down its concentration gradient.
    • Active transport of ions against their concentration gradient.
    • Osmosis of water through the phospholipid bilayer.

  14. Which feature of an exchange surface increases the rate of diffusion across it?

    • A reduced number of membrane channels for diffusing molecules.
    • A thick layer of membrane that increases the distance diffusion must travel.
    • A steep concentration gradient maintained across the surface.
    • A flat surface with a low ratio of surface area to volume.

  15. A sucrose solution of -400 kPa is placed in a bag with a cell of water potential -200 kPa. Which statement about osmosis is correct?

    • Water enters the cell by osmosis, moving from -400 kPa to -200 kPa.
    • Water leaves the cell by osmosis, moving from -200 kPa to -400 kPa.
    • Water moves into the cell by active transport against the gradient.
    • No water moves, because solutions with negative values are isotonic.

  16. Which statement explains how co-transport can use the sodium gradient to move glucose?

    • Glucose is moved by water passing through the membrane by osmosis.
    • Sodium ions diffuse back down their gradient through the same carrier, pulling glucose in with them.
    • Glucose diffuses through the sodium channel and out of the cell.
    • Sodium ions are hydrolysed to release glucose inside the cell.

  17. Why does an increase in surface area of a membrane increase the rate of transport across it?

    • The gradient is removed, so transport stops once the surface is larger.
    • The surface becomes impermeable, so molecules cross only by osmosis.
    • The membrane becomes thicker, so the substances are held in the cell for longer.
    • There are more sites available for transport, so more molecules can cross per unit time.

  18. Which of these is the best example of simple diffusion across a cell membrane?

    • Oxygen moving through the phospholipid bilayer into a cell down its concentration gradient.
    • Sodium ions leaving a neurone through a channel protein using energy from ATP.
    • Glucose moving into a cell through a carrier protein against its concentration gradient.
    • Water moving into a root hair cell through aquaporin channels in the membrane.

  19. Solution A has a water potential of -150 kPa and a plant cell has -250 kPa. Which statement describes net water movement?

    • Water moves into the cell from solution A, which has the higher water potential.
    • No net movement occurs, because the difference between the two values is only 100 kPa.
    • Water moves out of the cell into solution A, which has the lower water potential.
    • Water moves into the cell by active transport, because carriers pump water using ATP.

  20. Glucose uptake by a tissue continues when ATP production is blocked, but stops when the sodium gradient is removed. Which conclusion is best supported?

    • Glucose uptake happens by osmosis, because only water movement is affected by the sodium gradient.
    • Glucose uptake needs ATP directly at the carrier, consistent with simple active transport alone.
    • Glucose uptake is facilitated diffusion, which needs no sodium gradient or carrier at all.
    • Glucose uptake depends on a sodium gradient acting through a shared carrier, consistent with co-transport.

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