How to Revise Respiration — OCR A-Level Biology
Respiration is a topic in the OCR A-Level Biology specification. This guide covers learning objectives, examiner tips, common mistakes, and key terminology to help you revise effectively.
Examiner Tips for Respiration
- Ensure you can clearly distinguish between aerobic and anaerobic respiration pathways
- Practice calculating RQ values and interpreting what they indicate about the respiratory substrate
- Be prepared to describe the role of ATP as the immediate energy source for biological processes
- Use precise terminology when describing the roles of coenzymes and electron carriers
- Review the interrelationship between photosynthesis and respiration as specified in 5.2.1
Common Mistakes in Respiration
- Confusing the sites of different stages of respiration within the cell or mitochondrion
- Incorrectly identifying the products and reactants of the Krebs cycle
- Failing to explain the role of oxygen in oxidative phosphorylation
- Misunderstanding the chemiosmotic theory and the role of the proton gradient
- Incorrectly calculating or interpreting the respiratory quotient (RQ)
Key Marking Points
- Structure of the mitochondrion (inner/outer membranes, cristae, matrix, DNA)
- Glycolysis: phosphorylation of glucose, splitting into triose phosphate, oxidation to pyruvate, yield of ATP and reduced NAD
- Link reaction and its site
- Krebs cycle: formation of citrate, decarboxylation, dehydrogenation, reduction of NAD/FAD, substrate-level phosphorylation
- Role of coenzymes (NAD, FAD, coenzyme A)
- Oxidative phosphorylation: electron carriers, oxygen, mitochondrial cristae