Cellular Respiration | OCR A-Level Biology B (Advancing Biology) (H422)
Cellular Respiration
- 75 questions
- 5 subtopics
- Biology content, examined on all three papers
- Component 01, Component 02 and Component 03
Cellular Respiration is examined in all three written papers — the specification states that Components 01, 02 and 03 can each assess content from any of the five modules, so nothing is confined to one paper.
It covers glycolysis and the link reaction, the Krebs cycle, oxidative phosphorylation and anaerobic respiration, respiratory substrates and respiratory quotients and measuring the rate of respiration.
Sample questions from Cellular Respiration
Answer each one closed book first, then open the answer.
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Glycolysis and the link reaction
What happens to hexose bisphosphate in the lysis stage of glycolysis?
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It is split into two molecules of triose phosphate, each with three carbon atoms. -
Glycolysis and the link reaction
Where does the link reaction take place?
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In the matrix of the mitochondrion, where its enzymes are found. -
The Krebs cycle
Account for the number of carbon atoms in citrate and in oxaloacetate.
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Oxaloacetate has four carbon atoms and gains two from the acetyl group to give the six of citrate, and the two carbons lost as carbon dioxide return it to four. -
The Krebs cycle
What is the main purpose of the Krebs cycle in respiration?
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To generate reduced NAD and reduced FAD, which deliver hydrogen and electrons to oxidative phosphorylation where most of the ATP is made. -
Oxidative phosphorylation and anaerobic respiration
What is chemiosmosis?
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Chemiosmosis is the flow of protons back down their electrochemical gradient through ATP synthase, which drives the synthesis of ATP. -
Oxidative phosphorylation and anaerobic respiration
Describe what happens to pyruvate in a muscle cell respiring anaerobically.
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Pyruvate is reduced to lactate by lactate dehydrogenase, using the hydrogen carried by reduced NAD. -
Respiratory substrates and respiratory quotients
Explain why the respiratory quotient of a lipid is lower than that of a carbohydrate.
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A lipid contains proportionally far less oxygen and more hydrogen than a carbohydrate, so much more oxygen must be taken in from outside to oxidise it, while the carbon dioxide released per carbon atom is unchanged. -
Respiratory substrates and respiratory quotients
Compare the energy released per gram by lipid and by carbohydrate, and explain the difference.
Show the answer
Lipid releases roughly 39 kJ g⁻¹ against about 16 kJ g⁻¹ for carbohydrate, because a lipid has far more hydrogen atoms per gram, so more reduced NAD and reduced FAD are generated and more ATP is made in oxidative phosphorylation.
The 5 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Glycolysis and the link reaction | Recall questions on enzyme-controlled metabolic pathways, the phosphorylation, lysis and oxidation stages of glycolysis, dehydrogenases and NAD, substrate-level phosphorylation, the net yield of glycolysis, and the link reaction in the mitochondrial matrix and the role of coenzyme A. | 16 |
| The Krebs cycle | Recall questions on where the Krebs cycle happens, forming citrate from acetyl coenzyme A and oxaloacetate, decarboxylation and dehydrogenation, the carbon dioxide, reduced NAD, reduced FAD and ATP produced per turn and per glucose, its purposes, and why it stops without oxygen. | 14 |
| Oxidative phosphorylation and anaerobic respiration | Recall questions on the electron transport chain and cristae, the proton gradient and chemiosmosis, ATP synthase, oxygen as final electron acceptor, ATP yields and cyanide, lactate production in muscle, ethanol production in yeast, and the low ATP yield and fatigue of anaerobic respiration. | 18 |
| Respiratory substrates and respiratory quotients | Recall questions on respiratory substrates, calculating and interpreting respiratory quotients for carbohydrate, lipid and protein, quotients above 1.0 and in fermenting yeast, the energy released per gram by lipid and carbohydrate, and how amino acids enter respiration. | 13 |
| Measuring the rate of respiration | Recall questions on using a respirometer with soda lime and a control tube, calculating oxygen consumption and respiratory quotients from manometer readings, following yeast respiration with methylene blue, investigating temperature and sugar type, creating anaerobic conditions, and sources of error. | 14 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
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Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby topics
OCR A-Level Biology B (Advancing Biology) Active Recall Guide
Every topic, not just this one. 2,895 questions with their answers.