Lesson 5.2.1b

5.2.1b Light-dependent and light-independent stages Quiz: OCR Biology, Unit 6

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 5.2.1b, Light-dependent and light-independent stages: 20 multiple choice questions for the OCR Biology (H020), Unit 6: Energy for biological processes, written with Revision Ninja.

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The 20 questions

  1. Which molecule accepts carbon dioxide at the start of the light-independent stage?

    • Glycerate 3-phosphate (GP)
    • Pyruvate
    • Ribulose bisphosphate (RuBP)
    • Triose phosphate (TP)

  2. Which enzyme catalyses the fixation of carbon dioxide onto RuBP?

    • RuBisCO
    • ATP synthase
    • Photosystem II
    • NADP reductase

  3. Which two products of the light-dependent stage enter the Calvin cycle?

    • ADP and NADP
    • Water and carbon dioxide
    • Oxygen and glucose
    • ATP and reduced NADP

  4. What provides electrons to replace those lost from photosystem II in non-cyclic photophosphorylation?

    • Carbon dioxide
    • Water
    • Glucose
    • Reduced NADP

  5. Which gas is released as a by-product of the light-dependent stage?

    • Carbon dioxide
    • Hydrogen peroxide
    • Oxygen
    • Nitrogen

  6. What is the first stable product formed when carbon dioxide is fixed in the Calvin cycle?

    • Starch
    • Triose phosphate
    • Ribulose bisphosphate
    • Glycerate 3-phosphate

  7. What compound is regenerated using most of the triose phosphate produced in the Calvin cycle?

    • Glucose
    • RuBP
    • Acetyl CoA
    • GP

  8. Three molecules of carbon dioxide are fixed onto three molecules of RuBP. How many molecules of glycerate 3-phosphate are produced?

    • 9
    • 12
    • 6
    • 3

  9. In each turn of the Calvin cycle, six triose phosphate molecules are made. How many are used to regenerate RuBP?

    • 3
    • 6
    • 5
    • 1

  10. Which molecule is directly prevented from being reduced if thylakoid electron transport is blocked?

    • NADP
    • GP
    • RuBP
    • Pyruvate

  11. Which molecules run out rapidly when a photosynthesising plant enters darkness?

    • ATP and reduced NADP
    • Oxygen and glucose
    • RuBP and GP
    • Carbon dioxide and water

  12. What process uses light energy to split water during the light-dependent stage?

    • Decarboxylation
    • Photolysis
    • Phosphorylation
    • Glycolysis

  13. Which product is made in non-cyclic photophosphorylation but not in cyclic photophosphorylation?

    • RuBP
    • ATP
    • Reduced NADP
    • Triose phosphate

  14. Which enzyme catalyses the fixation of carbon dioxide onto ribulose bisphosphate?

    • RuBisCO
    • ATP synthase
    • PEP carboxylase
    • NAD dehydrogenase

  15. What happens to RuBP concentration when a photosynthesising leaf lacks carbon dioxide?

    • It decreases
    • It drops to zero
    • It remains constant
    • It increases

  16. A chloroplast fixes 12 carbon dioxide molecules per turn of the Calvin cycle. Five-sixths of the triose phosphate made is recycled to regenerate RuBP. How many triose phosphate molecules are left per turn for other uses?

    • 8
    • 4
    • 20
    • 12

  17. What primary shortage stops the Calvin cycle shortly after a plant enters darkness?

    • Absence of glucose
    • Lack of water
    • Excess of oxygen
    • Depletion of ATP

  18. Which molecule supplies energy to convert triose phosphate into RuBP?

    • Reduced NADP
    • ATP
    • Pyruvate
    • Glucose

  19. In which part of the chloroplast does the light-independent stage occur?

    • Stroma
    • Thylakoid membrane
    • Thylakoid lumen
    • Outer membrane

  20. Which photosystem is exclusively involved in cyclic photophosphorylation?

    • Neither photosystem
    • Both photosystems
    • Photosystem II
    • Photosystem I

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