Edexcel iGCSE Biology-2.36-2.38 aerobic and anaerobic respiration- Study Notes- New Syllabus
Edexcel iGCSE Biology-2.36-2.38 aerobic and anaerobic respiration- Study Notes- New syllabus
Edexcel iGCSE Biology-2.36-2.38 aerobic and anaerobic respiration- Study Notes -Edexcel iGCSE Biology – per latest Syllabus.
Key Concepts:
2.36 describe the differences between aerobic and anaerobic respiration
2.37 know the word equation and the balanced chemical symbol equation for aerobic respiration
in living organisms
2.38 know the word equation for anaerobic respiration in plants and in animals
Respiration – Aerobic & Anaerobic
📝 Introduction
Respiration = process by which cells release energy from food (mainly glucose) and store it in ATP.
Energy from ATP is used for:
- Muscle contraction
- Active transport
- Synthesis of macromolecules (proteins, DNA)
- Growth, repair, and other cellular activities
Two main types: Aerobic (with oxygen) and Anaerobic (without oxygen)
1. Aerobic Respiration
Definition: Respiration using oxygen to release energy from glucose.
Word Equation:
Glucose + Oxygen → Carbon dioxide + Water + Energy
Chemical Equation:
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (ATP)
Key Features:
- Requires oxygen
- Produces large amount of energy (~36–38 ATP per glucose)
- Waste products: CO₂ and H₂O
- Location: Mitochondria
- Most efficient type of respiration
2. Anaerobic Respiration
Definition: Respiration without oxygen, producing energy from glucose.
Word Equations:
| Organism | Word Equation | Notes |
|---|---|---|
| Humans (animals) | Glucose → Lactic acid + Energy | Small energy yield (~2 ATP); lactic acid → muscle fatigue |
| Plants & Yeast | Glucose → Ethanol + Carbon dioxide + Energy | Used in fermentation; small energy yield (~2 ATP) |
Key Features:
- Does not require oxygen
- Produces small amount of energy
- Location: Cytoplasm
- Waste products differ:
- Humans → Lactic acid
- Plants/yeast → Ethanol + CO₂
3. Differences Between Aerobic & Anaerobic Respiration
| Feature | Aerobic Respiration | Anaerobic Respiration |
|---|---|---|
| Oxygen needed? | Yes | No |
| Energy released | Large (~36–38 ATP) | Small (~2 ATP) |
| Products | CO₂ + H₂O | Lactic acid (humans); Ethanol + CO₂ (plants/yeast) |
| Location | Mitochondria | Cytoplasm |
| Efficiency | Very efficient | Less efficient |
| Example | Walking, resting | Intense exercise, fermentation in yeast |
⚡ Quick Recap
Aerobic: Glucose + O₂ → CO₂ + H₂O + lots of ATP (mitochondria)
Anaerobic (humans): Glucose → Lactic acid + little ATP (cytoplasm)
Anaerobic (plants/yeast): Glucose → Ethanol + CO₂ + little ATP (cytoplasm)
Main differences: oxygen use, energy yield, waste products, location, efficiency