amazon.co.ukBiochemistry and Respiration
A-Level Biology revision: Biochemistry and Respiration. Learning objectives, key points, worked examples and practice questions across AQA, Edexcel, OCR, WJEC and CCEA.
📌 Key Points
Key Fact: Glycolysis: glucose -> 2 pyruvate (cytoplasm); net 2 ATP, 2 NADH; Link: pyruvate -> acetyl CoA + CO₂ + NADH (mito matrix); Krebs: acetyl CoA + 3NAD⁺ + FAD + GDP -> 2CO₂ + 3NADH + FADH₂ + GTP; ETC: NADH/FADH₂ -> H⁺ gradient -> ATP synthase -> ATP
Key Fact: SLP: direct phosphate transfer (glycolysis, Krebs); OxPhos: H⁺ pumped across inner membrane, flow through ATP synthase
Key Fact: Theoretical: 10 NADH (2.5 each) + 2 FADH₂ (1.5 each) + 4 ATP = 32 ATP; Actual ~30-32
Key Fact: Anaerobic: animals: pyruvate + NADH -> lactate + NAD⁺ (lactate dehydrogenase); Yeast: pyruvate -> acetaldehyde + CO₂ -> ethanol + NAD⁺
Key Fact: Enzymes: globular proteins, active site, specific; Induced fit: substrate binding changes shape; Factors: temp, pH, [substrate], inhibitors (competitive/non-competitive)
Key Fact: Feedback inhibition: end product inhibits early enzyme; Allosteric: effector binds site != active site, changes conformation
🎯 Learning Objectives
- Detail glycolysis, link reaction, Krebs cycle, oxidative phosphorylation
- Explain substrate-level phosphorylation and oxidative phosphorylation (chemiosmosis)
- Calculate ATP yield per glucose (theoretical vs actual)
- Describe anaerobic respiration in animals (lactate) and yeast (ethanol)
- Explain enzyme structure, mechanism (lock-and-key, induced fit), factors affecting activity
- Understand metabolic pathways regulation: feedback inhibition, allosteric regulation
💡 Worked Example
Exam-Style Question
Question: Calculate total ATP from one glucose via aerobic respiration. Explain why yield is often less than theoretical
Model Answer:
Glycolysis: 2 ATP + 2 NADH (3-5 ATP); Link: 2 NADH (5 ATP); Krebs: 2 ATP + 6 NADH (15 ATP) + 2 FADH₂ (3 ATP) = 25-30 + 4 = 29-32 ATP. Less because: proton leak, shuttle costs (glycerol-3-P shuttle vs malate-aspartate), ATP for transport
❓ Practice Questions
Model answers are being added progressively - questions marked ✗ don't have one yet. Cross-check with your teacher or the official mark scheme.
Questions:
- Where does each stage of respiration occur?✗ answer coming soon
- Why does anaerobic respiration produce less ATP?✗ answer coming soon
- Explain induced fit model✗ answer coming soon
- How does cyanide affect respiration?✗ answer coming soon
🎬 Video Resources
- Biochemistry and Respiration - Overview -- YouTube Search
- Biochemistry and Respiration - Exam Questions -- YouTube Search
📄 Past Papers & Exam Resources
🔗 Further Reading & Resources
- Physics & Maths Tutor - Biochemistry and Respiration -- Free notes, worksheets, and past paper questions by topic
- Dr Frost Maths - Biochemistry and Respiration -- Free resources, slides, and interactive questions
- BBC Bitesize - Biochemistry and Respiration -- BBC Bitesize revision resources