12.2Respiration
Aerobic respiration — Cambridge IGCSE Biology 0610 Revision Notes & Topical Questions
5 min read 8 parts Lesson 3 of 4 1 quiz
Lesson summary
12.2 Aerobic respiration — IGCSE BIOLOGY notes: Define aerobic respiration and give its word and balanced equations.Aerobic respiration = the chemical reactions in cells that use oxygen to break down nutrient molecules to release energy.Breakdown — It is the complete breakdown of…
- Marking points
- Hydrogencarbonate indicator
- Investigation
- Mitochondria
- Breakdown — It is the complete breakdown of glucose
- Energy — A relatively large amount of energy is released for use in cell processes
Section 1 of 8Definition
Aerobic respiration
Aerobic respiration the chemical reactions in cells that use oxygen to break down nutrient molecules to release energy.
Breakdown
- It is the complete breakdown of glucose.
Energy
- A relatively large amount of energy is released for use in cell processes.
Location
- Most reactions take place in the mitochondria.
Section 2 of 8Word equation
Reactants
- Glucose and oxygen.
Products
- Carbon dioxide and water, plus useful cellular energy.
Equation
- Equation glucose + oxygen → carbon dioxide + water.
Section 3 of 8Balanced chemical equation (Supplement)
Equation
- C6H12O6 + 6O2 → 6CO2 + 6H2O.
Marking points
- Correct formulae for glucose and oxygen, correct formulae for carbon dioxide and water, and correct balancing.
Link
- It is the photosynthesis equation reversed.
Section 4 of 8Evidence of carbon dioxide production
Evidence of carbon dioxide production
Limewater
- Turns milky when carbon dioxide is bubbled through it.
Hydrogencarbonate indicator
- Changes from red towards yellow as carbon dioxide concentration rises.
Investigation
- Seal small organisms with indicator and compare with a control of glass beads.
Section 5 of 8Aerobic and anaerobic compared
| Feature | Aerobic | Anaerobic |
|---|---|---|
| Oxygen | Needed | Not needed |
| Glucose breakdown | Complete | Incomplete |
| Energy released per glucose | Relatively large | Relatively small |
| Products | Carbon dioxide and water | Lactic acid (animals); ethanol and carbon dioxide (yeast) |
Section 6 of 8More from the specification
More from the specification
Investigating Respiration Using Redox Indicators
- Methylene blue acts as an artificial electron acceptor, decolourising from blue to colourless as dehydrogenase enzymes transfer hydrogen atoms during active cellular respiration.
Temperature Dependency of Respiration Rate
- Plotting reaction velocity against temperature shows an initial rate increase up to an optimum temperature, beyond which thermal denaturation of respiratory enzymes causes rapid loss of catalytic function.
Complete Oxidation Equation
- Aerobic respiration completely oxidises glucose according to: C6H12O6 + 6O2 → 6CO2 + 6H2O, releasing energy to regenerate ATP molecules.
Independent variable
- The factor deliberately changed in an investigation.
Dependent variable
- The factor measured to see the effect of the change.
Muscle cell
- Mitochondria
Enzyme
- A protein that functions as a biological catalyst.
Section 7 of 8Key terms
| Term | Meaning |
|---|---|
| Aerobic respiration | Reactions in cells that use oxygen to break down nutrients and release energy. |
| Mitochondria | Organelles where most aerobic respiration takes place. |
| Glucose | The main nutrient molecule broken down in respiration. |
| Hydrogencarbonate indicator | Indicator that changes colour with carbon dioxide level. |
| Limewater | Solution that turns milky with carbon dioxide. |
Section 8 of 8Exam technique
1
Saying energy is made in respiration — energy is released from glucose.
2
Confusing respiration with breathing — respiration is a chemical process in cells.
3
Writing the equation unbalanced — six oxygen and six carbon dioxide and water molecules are needed.
4
Saying aerobic respiration happens only in animals — it happens in all living cells.
Marked practiceQuizzes for this lesson
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