Respiration | OCR A-Level Biology A (H420)

Respiration

74 questions
6 subtopics
Module 5: Communication, homeostasis and energy
Component 01 and Component 03

Respiration closes Module 5.

It covers the mitochondrion and the role of ATP, glycolysis, the link reaction and the Krebs cycle, oxidative phosphorylation and chemiosmosis, what happens when oxygen runs out, and how the respiratory quotient identifies the substrate being used.

Sample questions from Respiration

Answer each one closed book first, then open the answer.

Respiration, ATP and the mitochondrion

State two processes in animals that require ATP from respiration.

Show the answer
Muscle contraction and active transport.
Respiration, ATP and the mitochondrion

What are cristae and what is their function?

Show the answer
Cristae are folds of the inner mitochondrial membrane that increase surface area for electron carriers and ATP synthase.
Glycolysis

What happens in the second phosphorylation step during glycolysis?

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A second phosphate group is added from another ATP molecule.
Glycolysis

Describe what happens to triose phosphate in glycolysis.

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Triose phosphate is oxidised to pyruvate with the reduction of NAD to reduced NAD.
The link reaction and the Krebs cycle

In which part of the mitochondrion does the Krebs cycle occur?

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The Krebs cycle occurs in the mitochondrial matrix.
The link reaction and the Krebs cycle

How is ATP produced directly in the Krebs cycle?

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Substrate-level phosphorylation produces ATP directly from the transfer of a phosphate group to ADP.
Oxidative phosphorylation and chemiosmosis

What is the role of oxygen in oxidative phosphorylation?

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Oxygen is the final electron acceptor, combining with electrons and hydrogen ions to form water.
Oxidative phosphorylation and chemiosmosis

What is established across the inner mitochondrial membrane during oxidative phosphorylation?

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A proton gradient (electrochemical gradient) is established across the inner mitochondrial membrane.

The 6 subtopics

One subtopic is one session. Work down the list.

Subtopic	What it covers	Questions
Respiration, ATP and the mitochondrion	What respiration transfers and why plants, animals and microorganisms all need it, and the membranes, cristae, matrix and DNA of a mitochondrion.	10
Glycolysis	Where it happens, the two phosphorylation steps, the splitting of hexose bisphosphate into triose phosphate, and the net ATP and reduced NAD produced.	8
The link reaction and the Krebs cycle	Decarboxylation of pyruvate and the formation of acetyl coenzyme A, the citrate cycle, and the decarboxylation, dehydrogenation and coenzymes involved.	14
Oxidative phosphorylation and chemiosmosis	The electron transport chain and the role of oxygen, the proton gradient across the inner membrane, and how chemiosmotic theory explains ATP synthesis.	9
Anaerobic respiration	What happens to pyruvate in mammals and in yeast, why regenerating NAD matters, and how the ATP yield compares with aerobic respiration.	10
Respiratory substrates and the respiratory quotient	Why lipids yield more energy per unit mass than carbohydrates, how proteins are used, and the respiratory quotient, the respirometer and the variables to control.	23

Respiration is 74 of the 1,833 questions in the guide.Get the guide, £8

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.

Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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.
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.