IGCSE Biology
2026 - 2028
Syllabus Checklist
Topic 12: Respiration
1 Respiration
State the uses of energy
in living organisms, including:
muscle contraction, protein synthesis, cell division, active transport, growth, passage of nerve impulses, and maintaining a constant body temperature.
Investigate and describe the effect of temperature
on respiration in yeast.
2 Aerobic Respiration
Describe aerobic respiration
as the chemical reactions in cells that use oxygen to break down nutrient molecules to release energy.
State the word equation
for aerobic respiration as:
glucose + oxygen → carbon dioxide + water.
State the balanced chemical equation
for aerobic respiration as:
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O.
3 Anaerobic Respiration
Describe anaerobic respiration
as the chemical reactions in cells that break down nutrient molecules to release energy without using oxygen.
State that anaerobic respiration
releases much less energy per glucose molecule than aerobic respiration.
State the word equation
for anaerobic respiration in yeast as:
glucose → alcohol + carbon dioxide.
State the word equation
for anaerobic respiration in muscles during vigorous exercise as:
glucose → lactic acid.
State the balanced chemical equation
for anaerobic respiration in yeast as:
C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂.
State that lactic acid
builds up in muscles and blood during vigorous exercise, causing an oxygen debt
.
Outline how the oxygen debt
is removed after exercise, limited to:
▪ Continued fast heart rate transports lactic acid in the blood from the muscles to the liver.
▪ Continued deeper and faster breathing supplies oxygen for aerobic respiration of lactic acid.
▪ Aerobic respiration
of lactic acid in the liver.
Free Class
Videos, Notes & Solved Past Papers
