Lesson 3.5.2.1

3.5.2.1 Glycolysis, the link reaction and the Krebs cycle Quiz: AQA Biology, Unit 5

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.5.2.1, Glycolysis, the link reaction and the Krebs cycle: 20 multiple choice questions for the AQA Biology (7402), Unit 5: Energy transfers in and between organisms, written with Revision Ninja.

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The 20 questions

  1. Where in a eukaryotic cell does the process of glycolysis take place?

    • Cristae
    • Stroma
    • Mitochondrial matrix
    • Cytoplasm

  2. How many molecules of pyruvate are produced from one molecule of glucose in glycolysis?

    • Six
    • Four
    • One
    • Two

  3. What is the net gain of ATP in glycolysis for each glucose molecule?

    • Zero ATP
    • Six ATP
    • Four ATP
    • Two ATP

  4. What is the first step during the pathway of glycolysis?

    • Triose phosphate oxidation
    • Decarboxylation of pyruvate
    • Phosphorylation of glucose
    • Reduction of pyruvate

  5. Which reaction during glycolysis leads to the formation of reduced NAD?

    • Glucose phosphorylation
    • Pyruvate reduction
    • Triose phosphate oxidation
    • ATP hydrolysis

  6. Which molecule is pyruvate converted into during the link reaction?

    • Lactate
    • Oxaloacetate
    • Glucose
    • Acetate

  7. What carbon-number compound is formed when acetylcoenzyme A combines with a four-carbon compound?

    • Five-carbon compound
    • Six-carbon compound
    • Two-carbon compound
    • Three-carbon compound

  8. Where in the mitochondrion does the Krebs cycle take place?

    • Outer membrane
    • Cristae
    • Matrix
    • Intermembrane space

  9. By which process does pyruvate enter the mitochondrial matrix from the cytoplasm?

    • Facilitated diffusion
    • Active transport
    • Simple diffusion
    • Osmosis

  10. Which molecule is released as a waste product of the Krebs cycle?

    • Oxygen
    • Lactate
    • Water
    • Carbon dioxide

  11. Per acetylcoenzyme A in the Krebs cycle, how many reduced NAD molecules form?

    • One
    • Three
    • Four
    • Two

  12. How many carbon dioxide molecules are released per glucose molecule in aerobic respiration?

    • Two
    • Six
    • Four
    • Eight

  13. Which molecule is directly produced by substrate-level phosphorylation in the Krebs cycle?

    • ATP
    • Glucose
    • Pyruvate
    • Oxygen

  14. Which two types of molecules, besides carbohydrates, can act as respiratory substrates?

    • Lipids and proteins
    • Nucleic acids
    • Lipids and vitamins
    • Proteins and carbohydrates

  15. Where in a eukaryotic cell does the anaerobic process of glycolysis occur?

    • Cristae
    • Outer membrane
    • Mitochondrial matrix
    • Cytoplasm

  16. By what mechanism is ATP directly produced during the Krebs cycle?

    • Photophosphorylation
    • Oxidative phosphorylation
    • Substrate-level phosphorylation
    • Chemiosmosis

  17. Why does the Krebs cycle stop in the absence of oxygen?

    • ATP synthase blocks
    • NAD cannot reoxidise
    • Glucose cannot split
    • Pyruvate breaks down

  18. How many ATP molecules are produced by substrate-level phosphorylation in glycolysis for each glucose molecule, before the 2 ATP used at the start are subtracted?

    • 8
    • 6
    • 2
    • 4

  19. Which intermediate is a three-carbon molecule formed during glycolysis?

    • Acetylcoenzyme A
    • Triose phosphate
    • Citrate
    • Ribulose bisphosphate

  20. Which compound is formed when acetate combines with coenzyme A in the link reaction?

    • Glycerate 3-phosphate
    • Acetylcoenzyme A
    • Citrate
    • Pyruvate

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