OCR GCSE Biology A: Respiration and the synthesis and breakdown of biological molecules (J247) – Practice Questions

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 – examination boards hold copyright in their own papers. Use these alongside the official past papers from your board or school.

These questions cover topic B1.3 Respiration in OCR GCSE (9-1) Gateway Science Biology A (J247), Version 4.0 (August 2026), outcomes B1.3a to B1.3f. No B1.3 statement is Higher Tier only. Use the study guide and revision notes first. Course links: OCR GCSE Biology hub, checklist and free diagnostics. Where a question needs data on ATP yield, use 30 ATP per glucose for aerobic respiration and 2 for anaerobic. Atomic masses are not needed: use the masses given.

Questions

1. State two uses of ATP in a living cell. [2]

2. A student writes: “Respiration is breathing. Plants do not respire because they photosynthesise.” Explain one error in each sentence. [4]

3. A student puts germinating bean seeds in flask A and boiled, cooled bean seeds in flask B. Both flasks start at 21.0 °C. After two days, A is at 26.4 °C and B is at 21.3 °C.

(a) Calculate the temperature rise due to respiration, allowing for the control. [2] (b) Explain why flask B was boiled. [1] (c) State what the result shows about the energy transfer in respiration. [1]

4. Complete the comparison for respiration in a sprinter’s muscle cell and in a yeast cell without oxygen. [4]

	Sprinter’s muscle	Yeast
Oxygen needed?	no	(i)
Products	(ii)	(iii)
ATP per glucose	2	(iv)

5. A cell needs 450 ATP. Calculate how many glucose molecules it uses (a) aerobically and (b) anaerobically, and state how many times more glucose the anaerobic route needs. [3]

6. A student measures gas from yeast in glucose solution over 8 minutes. At 20 °C the volume is 8 cm³, at 30 °C it is 28 cm³, at 40 °C it is 36 cm³ and at 60 °C it is 0 cm³.

(a) Calculate the rate at 20 °C and at 30 °C, in cm³ per minute. [2] (b) By what percentage does the rate rise between 20 °C and 30 °C? [2] (c) Explain the result at 60 °C. [2]

7. A runner’s blood lactate was measured at four speeds: 8 km/h, 1.0 mmol/dm³; 12 km/h, 1.4; 16 km/h, 3.0; 20 km/h, 8.4.

(a) Describe the pattern. [2] (b) Explain the pattern. [3] (c) Calculate the percentage increase in lactate from 16 to 20 km/h. [2]

8. (a) Explain the terms monomer and polymer. [2] (b) Name the two types of smaller molecule that join to make a triglyceride. [1]

9. (a) Glucose (mass 180) joins fructose (mass 180) to make sucrose. Calculate the mass of sucrose. [2] (b) A polypeptide has 85 amino acids. State the number of water molecules released in making it. [1] (c) Glycerol (mass 92) joins three oleic acid molecules (mass 282 each) to make a triglyceride. Calculate its mass. [2]

10. A person eats cheese on bread. Explain why digestive enzymes are needed and what happens to the products. [5]

11. Plan an experiment to find how temperature changes the rate of anaerobic respiration in yeast. [8]

12. Compare anaerobic respiration in sprinters’ muscles and in yeast, and explain why both release less ATP than aerobic respiration. [6]

Answers

1. Any two: muscle contraction, active transport, building (synthesising) large molecules, cell division, nerve impulses [1][1] [2] Examiner insight: Name a specific use. “Energy for the cell” repeats the stem and gains nothing.

2. Respiration is a chemical process in cells that transfers energy to ATP [1]; breathing only moves air in and out of the lungs [1]. Plants respire in all living cells, all the time [1]; photosynthesis makes the glucose that respiration uses and does not replace it [1] [4] Examiner insight: Each error needs the correction as well as the identification. Say what is wrong and what is right.

3. (a) Rise in A = 26.4 − 21.0 = 5.4 [1]; minus rise in B (0.3) = 5.1 °C [1] [2] (b) Boiling denatured the enzymes, so the seeds cannot respire [1] [1] (c) Respiration transfers energy as heat to the surroundings (it is exothermic) [1] [1] Examiner insight: A control is only explained when you say what it removes. “To compare” is too vague.

4. (i) no [1]; (ii) lactic acid [1]; (iii) ethanol and carbon dioxide [1]; (iv) 2 [1] [4] Examiner insight: Both products are needed for yeast. Writing carbon dioxide for muscle is a common slip.

5. (a) 450 ÷ 30 = 15 glucose [1]; (b) 450 ÷ 2 = 225 glucose [1]; 225 ÷ 15 = 15 times more [1] [3] Examiner insight: Show each division and state the final ratio clearly, so that the reasoning behind your answer is visible.

6. (a) 8 ÷ 8 = 1.0 cm³ per min [1]; 28 ÷ 8 = 3.5 cm³ per min [1] [2] (b) (3.5 − 1.0) ÷ 1.0 × 100 [1] = 250% [1] [2] (c) Enzymes are denatured at high temperature [1]; active sites change shape, so glucose no longer fits and no respiration occurs [1] [2] Examiner insight: Divide by the original value in percentage change; dividing by the new value is a frequent loss.

7. (a) Lactate stays low and rises slowly at 8 to 12 km/h [1]; it increases sharply above 16 km/h [1] [2] (b) At high speed muscles need more ATP [1]; oxygen supply cannot meet demand, so more anaerobic respiration [1]; this makes lactic acid, which builds up [1] [3] (c) (8.4 − 3.0) ÷ 3.0 × 100 [1] = 180% [1] [2] Examiner insight: A description uses figures from the table; an explanation links the cause to oxygen and ATP.

8. (a) A monomer is a small unit [1]; a polymer is a long chain of many monomers joined together [1] [2] (b) Glycerol and fatty acids [1] [1] Examiner insight: Lipids are not chains of one repeating unit, so avoid calling the fatty acid a monomer of the lipid.

9. (a) 180 + 180 = 360 [1]; minus 18 for the water lost = 342 [1] [2] (b) 84 [1] [1] (c) 92 + 3 × 282 = 938 [1]; minus 3 × 18 = 54 gives 884 [1] [2] Examiner insight: Subtract the mass of the water from every join. The number of waters is one less than the monomers in a chain.

10. Cheese contains protein and fat; bread contains starch [1]. These are large molecules and cannot be absorbed [1]. Protease makes amino acids, lipase makes glycerol and fatty acids, carbohydrase makes sugars [1]. Cells rebuild amino acids into their own proteins [1]; glucose is used in respiration to make ATP [1] [5] Examiner insight: Match each enzyme to its substrate and product. A list of enzyme names alone earns little.

11. In every flask keep the yeast mass, glucose volume and glucose concentration equal, using boiled, cooled glucose solution [1]; add a layer of oil to exclude oxygen [1]. Place flasks in water baths at several temperatures, for example 15, 25, 35 and 45 °C [1]; allow time to reach temperature [1]. Collect the gas in a gas syringe [1] over a fixed time [1]. Rate = volume ÷ time, repeated and a mean taken [1]. Plot rate against temperature to find the optimum [1] [8] Examiner insight: Name the independent variable, the dependent variable and at least two controlled variables; vague “keep it fair” statements earn nothing.

12. Both use glucose without oxygen [1]. Muscle makes lactic acid [1]. Yeast makes ethanol and carbon dioxide [1]. Both make only 2 ATP per glucose [1]. Glucose is only partly broken down [1]; energy remains in lactic acid or ethanol [1] [6] Examiner insight: For a comparison, state a similarity and a difference in the same sentence structure.

Where marks are usually lost

• Treating respiration as breathing.
• Saying plants respire only in the dark.
• Mixing up lactic acid and ethanol.
• Writing “makes energy” rather than ATP or “transfers energy”.
• Dividing by the new value in percentage change.
• Forgetting units, or leaving out “per minute”.
• Using the number of monomers instead of the number of joins.
• Giving the ATP figures the wrong way round: aerobic respiration gives the large yield.
• Naming only one product of fermentation in yeast.
• Describing a control as “to compare” without saying what it removes.

Next steps

• Study guide
• Revision notes
• OCR GCSE Biology hub
• Printable checklist
• All free 10-minute diagnostics
• Book a free trial class: /trial/

Official syllabus

OCR, GCSE (9-1) Gateway Science Suite Biology A (J247), Version 4.0 (August 2026), first assessment 2018, topic B1.3 Respiration.