LEARNING OBJECTIVES
By the end of this chapter, you should be able to:
- state energy uses
- compare aerobic and anaerobic respiration
- write equations
- explain oxygen debt
THE BIG IDEA
How cells release energy with or without oxygen.
This chapter builds each process from its structures, inputs and outputs. Follow the connections rather than memorising isolated facts, then use precise biological terms when explaining cause and effect.
01
SECTION 01
Aerobic respiration
Aerobic respiration uses oxygen to break down glucose and releases energy for contraction, synthesis, division, active transport, growth, impulses and temperature control.
DETAILED EXPLANATION
- Most aerobic respiration occurs in mitochondria.
- Yeast respiration rises with temperature to an enzyme optimum, then falls with denaturation.
FORMULA OR EQUATION
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O
02
SECTION 02
Anaerobic pathways
Without oxygen, glucose is incompletely broken down and releases much less energy.
DETAILED EXPLANATION
- Yeast: glucose → ethanol + carbon dioxide; balanced: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂.
- Muscle: glucose → lactic acid during vigorous activity.
1yeast → ethanol + CO₂→
2muscle → lactic acid
03
SECTION 03
Oxygen debt
Lactic acid accumulation creates an oxygen debt removed during recovery.
DETAILED EXPLANATION
- Heart rate stays high to carry lactic acid to liver.
- Breathing remains faster and deeper to supply oxygen.
- Liver aerobically respires lactic acid.
QUICK CHAPTER SUMMARY
The ideas to carry forward
- Respiration releases usable energy.
- Aerobic respiration yields more energy.
- Anaerobic products differ.
- Recovery removes lactic acid.