IGCSE Biology: Respiration — Practice Questions (Cambridge 0610)

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs — Cambridge International holds copyright in its own papers. Use these alongside the official past papers available from your board.

Each question practises a skill tested in the June 2024 Paper 42. After each answer there is an examiner insight, a mark-scheme insight or a tip, and (where a close match exists) the real question to try next. Questions marked (Extended) test Supplement content.

Tier note: questions marked (Extended) go beyond 0610 Core: balanced chemical equations for aerobic and anaerobic respiration, and oxygen debt (12.2, 12.3). All other questions are answerable by a 0610 Core candidate.

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Questions

1. Respiration takes place in every living cell.

(a) Describe what is meant by respiration.

(b) State two uses of the energy released by respiration in the human body. [3]

2. Write word equations for:

(a) aerobic respiration

(b) anaerobic respiration in yeast. [4]

3. (Extended) Write balanced chemical equations, using chemical formulae, for:

(a) aerobic respiration

(b) anaerobic respiration in yeast. [4]

4. A student places yeast in a flask of glucose solution kept at 30 °C and pours a thin layer of oil over the surface of the liquid. A tube from the flask leads to a gas syringe. The syringe reads 6 cm³ after 4 minutes and 27 cm³ after 10 minutes.

(a) Calculate the mean rate of carbon dioxide production between 4 minutes and 10 minutes. Include the unit.

(b) Suggest why the student added the layer of oil.

(c) After 50 minutes the syringe reading stops increasing, even though the temperature has not changed. Suggest one reason why. [4]

5. The student in Question 4 sets up a second flask in exactly the same way, but keeps it at 90 °C. No gas is collected at all. Explain why. [3]

6. Yeast is used in bread-making and in the production of fuel ethanol.

(a) Name the product of anaerobic respiration in yeast that makes bread dough rise.

(b) Name the product of anaerobic respiration in yeast that is collected to make a biofuel. [2]

7. (Extended) A swimmer races 200 m as fast as she can. For several minutes after the race her heart rate and breathing rate stay high, even though she is resting. Explain why. [4]

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Answers

1. (a) The chemical reactions in cells [1] that break down nutrient molecules (such as glucose) to release energy [1].

(b) Any two of: muscle contraction, protein synthesis, cell division, growth, passage of nerve impulses, maintaining a constant body temperature [1 for two correct]. Respiration releases energy; never say it “makes” or “produces” energy.

Tip: “Powerhouse of the cell” is not an answer. Name the process precisely, for example “aerobic respiration releases energy from glucose”.

Try the real question next: Cambridge IGCSE Biology 0610, June 2024, Paper 42, Question 1(a)(i).

2. (a) glucose + oxygen → carbon dioxide + water [1 for reactants, 1 for products].

(b) glucose → alcohol (ethanol) + carbon dioxide [1 for reactant, 1 for both products]. No oxygen appears on the left: that is what makes it anaerobic.

Examiner insight (Cambridge 0610 June 2024 examiner report, Paper 42, Question 1(b)): In a question asking for the balanced chemical equation for yeast, most candidates knew it was anaerobic respiration and started correctly with glucose; fewer knew the product ethanol well enough to write its formula. Learn ethanol as a product of yeast, never lactic acid.

Source for the examiner insights on this page: Cambridge IGCSE Biology 0610 June 2024 Principal Examiner Report for Teachers, Paper 0610/42 section, paraphrased.

Try the real question next: Cambridge IGCSE Biology 0610, June 2024, Paper 42, Question 1(b).

3. (Extended) (a) C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O [1 for correct formulae, 1 for balancing].

(b) C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ [1 for glucose as the only reactant, 1 for correct, balanced products]. Check: 6 C, 12 H and 6 O on each side.

Examiner insight (Cambridge 0610 June 2024 examiner report, Paper 42, Question 1(b)): Many candidates could not recall the formula of ethanol (C₂H₅OH), so they could not balance the yeast equation. Learn it alongside the glucose formula.

Try the real question next: Cambridge IGCSE Biology 0610, June 2024, Paper 42, Question 1(b).

4. (a) Volume produced = 27 − 6 = 21 cm³; time = 10 − 4 = 6 minutes [1]. Rate = 21 ÷ 6 = 3.5 cm³ per minute (cm³/min) [1 for value and unit].

(b) To stop oxygen entering the glucose solution, so the yeast must respire anaerobically [1].

(c) All the glucose has been used up [1] (or: the ethanol produced has built up to a level that is toxic to the yeast).

Examiner insight (Cambridge 0610 June 2024 examiner report, Paper 42, Question 1(c)): Many candidates wrongly said the oil stops evaporation, as in a transpiration experiment; others wrote “air” or “gas” where “oxygen” was needed. In the rate calculation, some wrote “m” for minutes, which is the symbol for metres.

Try the real question next: Cambridge IGCSE Biology 0610, June 2024, Paper 42, Question 1(c).

5. At 90 °C the enzymes in the yeast cells that control respiration are denatured [1]. The shape of the active site changes, so glucose (the substrate) no longer fits / is no longer complementary to it [1]. So the yeast cannot respire and no carbon dioxide is released [1].

Examiner insight (Cambridge 0610 June 2024 examiner report, Paper 42, Question 1(c)(iv)): Some candidates wrote as if yeast itself were an enzyme that becomes denatured. Yeast is a living fungus; it is the enzymes inside its cells that denature.

Try the real question next: Cambridge IGCSE Biology 0610, June 2024, Paper 42, Question 1(c)(iv).

6. (a) Carbon dioxide [1]: the gas bubbles get trapped in the dough.

(b) Ethanol (alcohol) [1].

Examiner insight (Cambridge 0610 June 2024 examiner report, Paper 42, Question 1(d)): When asked for a use of the carbon dioxide from yeast, some candidates gave uses of yeast in general, such as biofuel or wine. Read which product the question is about.

Try the real question next: Cambridge IGCSE Biology 0610, June 2024, Paper 42, Question 1(d).

7. (Extended) During the race her muscles respire anaerobically as well as aerobically, so lactic acid builds up in the muscles and blood [1]. This causes an oxygen debt [1]. Afterwards, the fast heart rate carries lactic acid in the blood from the muscles to the liver [1], and the fast, deep breathing supplies the oxygen needed for aerobic respiration of the lactic acid [1].

Tip: Link each observation (heart rate, breathing rate) to its own job in removing the oxygen debt; a single vague sentence about “needing more oxygen” will not collect all the marks.

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Where marks are usually lost

• Writing “air” or “gas” when the answer needs “oxygen” (or “carbon dioxide”).
• Saying respiration “produces” or “makes” energy instead of releasing it.
• Treating yeast as an enzyme: the yeast is killed because its enzymes denature.
• Leaving out units, or using “m” for minutes, in rate calculations.
• Not knowing the formula of ethanol, so the yeast equation cannot be balanced.