IGCSE Biology: Movement Into and Out of Cells — Practice Questions (Cambridge 0610)

These are original questions written for Marlbridge, in the style and at the standard of the examination. They are not reproduced past-paper questions — Cambridge International holds copyright in its own papers. Use these alongside the official past papers available free from your board.

Related: Movement into and out of cells study guide and revision notes

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Section A (Core)

1. Define diffusion. [2]

2. Name four factors that influence the rate of diffusion. [4]

3. State the source of energy used in active transport. [1]

Section B (Core and Supplement)

4. Root hair cells absorb mineral ions from the soil even when the concentration of those ions is lower in the soil than inside the root hair cell.

(a) Identify the process responsible for this movement. [1] (b) Explain why this process, rather than diffusion, must be responsible. [3]

5. A plant cell is placed into a concentrated sugar solution and loses water, causing the cell membrane to pull away from the cell wall.

(a) (Supplement) Name the condition being described. [1] (b) Explain, using the term water potential, why water leaves the cell in this situation. [3]

6. A gas exchange surface in the lungs relies on diffusion to move oxygen into the blood.

(a) State two factors, from those named in this topic, that would increase the rate of this diffusion. [2] (b) Explain why a large surface area increases the rate of diffusion. [2]

7. Complete the following comparison: for each process, state the direction of movement relative to the concentration gradient and whether energy from respiration is required.

(a) Diffusion [2] (b) Osmosis [2] (c) Active transport [2]

8. A student places dialysis tubing filled with concentrated sugar solution into a beaker of pure water and observes the tubing swell over time.

(a) Explain, in terms of water potential, why the tubing swells. [3] (b) Suggest what would happen if the experiment were repeated with the tubing placed in a very concentrated salt solution instead of pure water. [2]

9. A wilted houseplant is watered and, within a few hours, its leaves and stems return to being firm and upright.

(a) (Supplement) Name the state the plant cells are in once they have recovered. [1] (b) Explain how water uptake restores this firmness, referring to the cell wall. [3]

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Answers

1. Diffusion is the net movement of particles from a region of their higher concentration to a region of their lower concentration (down a concentration gradient), as a result of their random movement [2].

2. Surface area, temperature, concentration gradient, distance [4].

3. Respiration [1].

4. (a) Active transport [1]. (b) Diffusion only moves particles from a region of higher concentration to a region of lower concentration (down a concentration gradient) [1]; here, the ions are moving from a lower concentration (in the soil) to a higher concentration (inside the root hair cell), which is against the concentration gradient [1], and movement against a concentration gradient requires energy from respiration, which only active transport (not diffusion) provides [1].

5. (a) Plasmolysis [1]. (b) Water moves by osmosis from a region of higher water potential to a region of lower water potential [1]. The concentrated sugar solution outside the cell has a lower water potential than the cell’s contents [1], so water moves out of the cell, down the water potential gradient, causing the cell to lose water and the membrane to pull away from the cell wall [1].

6. (a) Any two of: larger surface area, higher temperature, steeper concentration gradient, shorter distance [2]. (b) A larger surface area provides more space across which diffusion can occur simultaneously, increasing the total rate at which particles cross the gas exchange surface in a given time [2].

7. (a) Diffusion: high to low concentration (down the concentration gradient); no energy from respiration required (uses kinetic energy of random particle movement only) [2]. (b) Osmosis: high to low water potential; no energy from respiration required [2]. (c) Active transport: low to high concentration (against the concentration gradient); energy from respiration is required [2].

8. (a) The concentrated sugar solution inside the dialysis tubing has a lower water potential than the pure water outside [1]. Water molecules move by osmosis from the region of higher water potential (the pure water outside) to the region of lower water potential (the sugar solution inside), through the partially permeable dialysis tubing, causing the tubing to swell as water enters [1–2]. (b) If the tubing were placed in a very concentrated salt solution instead, the solution outside could have a lower water potential than the sugar solution inside the tubing, in which case water would move out of the tubing by osmosis instead, causing it to shrink rather than swell [2].

9. (a) Turgid [1]. (b) As the plant cells absorb water by osmosis, the water inside each cell increases the pressure pushing outward on the cell wall (turgor pressure) [1–2]. Because the cell wall is rigid and resists this outward pressure, the cells become firm rather than continuing to expand indefinitely, and this turgor pressure across many cells is what gives the whole plant its firm, upright structure once enough water has been absorbed [1].

A note on exam technique for this topic

Question 4 rewards the comparison-based reasoning the study guide identifies as the most valuable exam skill on this topic: identifying which of the three processes is occurring in an unfamiliar context by checking the direction of movement relative to the concentration gradient and whether energy is required, rather than simply naming a process from a half-remembered definition. Question 5 rewards Core candidates keeping the Supplement-only water potential language distinct from the simpler Core statement that water moves by osmosis through a partially permeable membrane — know which level of explanation your tier actually requires.