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CAIE IGCSE Biology 12.3 Anaerobic Respiration Questions

Practise anaerobic-respiration questions on oxygen shortage, yeast fermentation, muscle lactic acid, energy yield and oxygen-debt recovery.

Syllabus
2026–2028
Course
Biology 0610

Exam points

  • compare anaerobic and aerobic respiration by oxygen use, energy yield per glucose and products
  • write glucose → alcohol + carbon dioxide as the yeast anaerobic word equation
  • interpret yeast carbon-dioxide evidence using oxygen exclusion, cloudy limewater or glucose depletion
  • distinguish yeast alcohol and carbon dioxide from muscle lactic acid in fermentation questions
  • state C6H12O6 → 2C2H5OH + 2CO2 with correct formulae and coefficients
  • use the 1:2:2 ratio to compare glucose, ethanol and carbon-dioxide molecules
  • distinguish the yeast anaerobic equation from aerobic-respiration and photosynthesis equations
  • write glucose → lactic acid and link vigorous exercise or limited oxygen to muscle anaerobic respiration
  • explain lactic-acid build-up in muscles and blood as the cause of oxygen debt
  • interpret recovery graphs to identify when oxygen consumption remains above resting level
  • explain recovery through continued fast heart rate, deeper breathing and lactic-acid transport to the liver
  • explain liver aerobic breakdown of lactic acid into carbon dioxide and water

Covered syllabus points

12.3.1—Anaerobic respiration as the chemical12.3.2—Anaerobic respiration releases much12.3.3—Word equation for anaerobic12.3.4—Word equation for anaerobic12.3.5—Anaerobic respiration equation12.3.6—Lactic acid builds up in muscles12.3.7—How the oxygen debt is removed after

Question 1

[Maximum number: 1]

Which statement about both aerobic and anaerobic respiration is correct?

A

They break down C6H12O6\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}.

B

They produce an oxygen debt.

C

They use CO2\mathrm{CO}_{2}.

D

They use O2\mathrm{O}_{2}.

Question 2

[Maximum number: 1]

Which statement about anaerobic respiration is correct?

A

Anaerobic respiration requires oxygen and releases less energy per glucose molecule than aerobic respiration.

B

Anaerobic respiration requires oxygen and releases more energy per glucose molecule than aerobic respiration.

C

Anaerobic respiration does not require oxygen and releases less energy per glucose molecule than aerobic respiration.

D

Anaerobic respiration does not require oxygen and releases more energy per glucose molecule than aerobic respiration.

Question 3

[Maximum number: 1]

What is the word equation for anaerobic respiration in yeast?

A

glucose → alcohol + carbon dioxide

B

glucose → alcohol

C

glucose → lactic acid + carbon dioxide

D

glucose → lactic acid

All question bank results loaded