Anaerobic respiration — Paper 2 · IGCSE Biology (9-1) 0970

21 Yeast is able to respire both aerobically and anaerobically. Which statement describes the waste products of yeast respiration? A Aerobic respiration produces alcohol as one of its waste products. B Aerobic respiration produces three times as much carbon dioxide as anaerobic respiration from one molecule of glucose. C Anaerobic respiration and aerobic respiration both produce the same amount of carbon dioxide from one molecule of glucose. D Anaerobic respiration produces three times as much carbon dioxide as aerobic respiration from one molecule of glucose.

1 marks

Answer: B

This question in 0970/21 May/June 2018

21 Lactic acid builds up in the muscles during vigorous exercise. During recovery, how is this lactic acid removed? A aerobic respiration of lactic acid in the liver B anaerobic respiration of lactic acid in the muscles C excretion of lactic acid by the lungs D removal of lactic acid by the alimentary canal

1 marks

Answer: A

This question in 0970/22 Oct/Nov 2019

21 The diagram shows an experiment to investigate the respiration of yeast. Oil prevents oxygen entering the glucose and yeast suspension. delivery tube thin layer of oil bubble of gas glucose and yeast limewater suspension If no oxygen is present in the glucose and yeast suspension, what will occur? A Ethanol will be produced and the limewater will stay clear. B Ethanol will be produced and the limewater will go cloudy. C Lactic acid will be produced and the limewater will stay clear. D Lactic acid will be produced and the limewater will go cloudy.

1 marks

Answer: B

This question in 0970/21 May/June 2020

37 What is the role of anaerobic respiration in bread-making? A to produce alcohol to flavour the bread B to produce gas to make the bread rise C to release enough energy to bake the bread D to release enough lactic acid to kill the yeast

1 marks

Answer: B

This question in 0970/21 May/June 2020

22 The formula C2H5OH represents a chemical produced during anaerobic respiration. What is this chemical? A alcohol B glucose C glycogen D lactic acid

1 marks

Answer: A

This question in 0970/22 May/June 2020

37 What is the role of anaerobic respiration in bread-making? A to produce alcohol to flavour the bread B to produce gas to make the bread rise C to release enough energy to bake the bread D to release enough lactic acid to kill the yeast

1 marks

Answer: B

This question in 0970/22 May/June 2020

21 What is produced during anaerobic respiration in muscles? A carbon dioxide B ethanol C lactic acid D water

1 marks

Answer: C

This question in 0970/22 Oct/Nov 2020

24 After vigorous exercise, an athlete continues to breathe deeply during the recovery period. During this recovery period the oxygen debt is removed. Which reaction is used to remove the oxygen debt? A aerobic respiration of lactic acid in the liver B aerobic respiration of lactic acid in the muscles C anaerobic respiration of lactic acid in the liver D anaerobic respiration of lactic acid in the muscles

1 marks

Answer: A

This question in 0970/22 May/June 2021

23 Which statement about lactic acid is correct? A Lactic acid is a product of anaerobic respiration in yeast. B Lactic acid build-up in tissues can lead to an oxygen debt. C Lactic acid is produced from sucrose during anaerobic respiration. D Lactic acid is transported from the liver to the muscles after exercise.

1 marks

Answer: B

This question in 0970/22 Oct/Nov 2021

38 What is the useful product of anaerobic respiration in the manufacture of bread? A carbon dioxide B ethanol C lactic acid D oxygen

1 marks

Answer: A

This question in 0970/22 Oct/Nov 2021

22 What is the balanced chemical equation for anaerobic respiration in yeast? A C6H12O6  2CO2 + 6H2O B C6H12O6  6CO2 + 6H2O C C6H12O6  2C2H5OH + 2CO2 D C6H12O6  2C2H5OH + 2H2O

1 marks

Answer: C

This question in 0970/21 May/June 2022

22 During vigorous exercise, lactic acid builds up in muscles leading to an oxygen debt. Which statement describes a stage in the removal of the oxygen debt during recovery? A Anaerobic respiration breaks down lactic acid in the muscles. B Aerobic respiration breaks down lactic acid in the muscles. C Anaerobic respiration breaks down lactic acid in the liver. D Aerobic respiration breaks down lactic acid in the liver.

1 marks

Answer: D

This question in 0970/22 May/June 2022

22 Which row shows the products of anaerobic respiration in humans and yeast? products in humans products in yeast A lactic acid only alcohol only B lactic acid only alcohol and carbon dioxide C lactic acid and carbon dioxide alcohol only D lactic acid and carbon dioxide alcohol and carbon dioxide

1 marks

Answer: B

This question in 0970/22 Oct/Nov 2022

21 In the chemical equation for anaerobic respiration in yeast, the numbers have been replaced by the letters W, X, Y and Z. CWHXOW → YCYHZOH + YCOY Which number is Z? A 2 B 5 C 6 D 12

1 marks

Answer: B

This question in 0970/21 May/June 2023

22 A student measured their oxygen consumption before, during and after exercise. The results are shown in the graph. at rest during exercise after exercise 3.0 2.5 2.0 oxygen consumption 1.5 / dm3 per minute 1.0 0.5 0.0 0 5 10 15 20 25 time / minutes At which time is the oxygen debt being removed? A 5–10 minutes B 5–15 minutes C 15–20 minutes D 20–25 minutes

1 marks

Answer: C

This question in 0970/21 May/June 2023

22 In which organ is lactic acid respired aerobically to remove an oxygen debt? A brain B heart C liver D lungs

1 marks

Answer: C

This question in 0970/22 May/June 2023

40 Yeast carries out anaerobic respiration, making carbon dioxide and ethanol as end-products. Which end-products can be used to make biofuel and bread? biofuel bread A carbon dioxide carbon dioxide B carbon dioxide ethanol C ethanol carbon dioxide D ethanol ethanol

1 marks

Answer: C

This question in 0970/22 May/June 2023

23 Yeast cells can convert glucose into alcohol and carbon dioxide. Which statement about this process is correct? A The alcohol produced can be used to make bread rise. B The carbon dioxide produced can be burnt as a biofuel. C The yeast cells are using oxygen for this process. D The yeast cells are carrying out anaerobic respiration.

1 marks

Answer: D

This question in 0970/22 Oct/Nov 2023

24 What is the correct balanced equation for one type of respiration? A C2H5OH → 2C6H12O6 + 2CO2 B 2C2H5OH → C6H12O6 + 2H2O C C6H12O6 → 2C2H5OH + 2CO2 D C6H12O6 → 2C2H5OH + 2H2O

1 marks

Answer: C

This question in 0970/22 Oct/Nov 2023

24 Vigorous exercise can cause an oxygen debt. Which process removes the oxygen debt? A aerobic respiration of lactic acid in the liver B a decrease in breathing rate C a decrease in heart rate D an increase in blood supply to the skin

1 marks

Answer: A

This question in 0970/21 May/June 2024

23 A student investigates the rate of anaerobic respiration in yeast. The total volume of carbon dioxide produced is measured every 10 minutes for 40 minutes. The table shows the results. total volume of time / minutes carbon dioxide produced / cm3 0 6 10 30 20 37 30 40 40 41 Between which times is the rate of anaerobic respiration fastest? A 0–10 minutes B 10–20 minutes C 20–30 minutes D 30–40 minutes

1 marks

Answer: A

This question in 0970/22 Oct/Nov 2024

22 After a race, athletes experience oxygen debt. The diagram shows how the oxygen debt is removed. lactic acid forms in the muscles lactic acid moves in X the blood to the liver faster breathing supplies extra oxygen What happens at X? A aerobic respiration of glucose B aerobic respiration of lactic acid C anaerobic respiration of glucose D anaerobic respiration of lactic acid

1 marks

Answer: B

This question in 0970/22 May/June 2025

17 A person exercised vigorously for one minute and then rested for one hour. Which statements about lactic acid are correct? 1 During exercise, lactic acid is produced in the muscles and diffuses into the blood. 2 The blood transports lactic acid to the liver. 3 Lactic acid is broken down by anaerobic respiration. A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 2 only

1 marks

Answer: B

This question in 0970/22 Oct/Nov 2025