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
Question 1
Which statement about both aerobic and anaerobic respiration is correct?
A
They break down .
B
They produce an oxygen debt.
C
They use .
D
They use .
Question 2
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
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
Question 4
Human muscle cells use anaerobic respiration during vigorous exercise.
State the word equation for anaerobic respiration in humans.
Question 5
Alcohol can be made by the microorganism yeast.
State the balanced chemical equation for the production of alcohol by yeast.
Question 6
During exercise an oxygen debt may occur in muscles.
What is the cause of this oxygen debt?
A
Aerobic respiration causes a decrease in lactic acid.
B
Aerobic respiration causes an increase in lactic acid.
C
Anaerobic respiration causes a decrease in lactic acid.
D
Anaerobic respiration causes an increase in lactic acid.
Question 7
An athlete monitored their heart rate and breathing rate before, during and after vigorous exercise.
Fig. 6.1 shows the results.
Fig. 6.1
Complete the sentences to describe and explain the results shown in Fig. 6.1.
After exercise, it takes ____ minutes for the athlete's breathing rate to return to its resting rate.
The heart rate decreases by ____ beats per minute between 20 and 40 minutes.
The heart rate and breathing rate do not immediately return to their resting rates because anaerobic respiration has occurred.
Lactic acid has built up in ____ causing an oxygen ____.
The heart rate remains high to transport lactic acid to the ____.
The breathing rate remains high to supply ____ for the ____ respiration of lactic acid.
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