Lesson 5.2.2

5.2.2 Light-dependent reactions Quiz: Pearson Edexcel Biology A (Salters-Nuffield), Unit 5

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 5.2.2, Light-dependent reactions: 20 multiple choice questions for the Pearson Edexcel Biology A (Salters-Nuffield) (9BI0), Unit 5: On the Wild Side, written with Revision Ninja.

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The 20 questions

  1. Where do the light-dependent reactions of photosynthesis take place?

    • In the outer envelope of the chloroplast
    • On the thylakoid membranes of the chloroplast
    • In the stroma, where the Calvin cycle occurs
    • In the cytoplasm outside the chloroplast

  2. What happens to chlorophyll electrons when light is absorbed in the light-dependent reactions?

    • They are excited and passed along a transport chain
    • They are converted into glucose directly
    • They are stored unchanged in the stroma until dark
    • They are destroyed and the chlorophyll molecule is discarded

  3. What is the source of electrons that replace those lost from chlorophyll?

    • Photolysis of water
    • Oxidation of glucose
    • Breakdown of ATP
    • Reduction of carbon dioxide

  4. Which gas is released as a by-product of photolysis of water?

    • Carbon dioxide
    • Hydrogen
    • Nitrogen
    • Oxygen

  5. What is produced by photophosphorylation in the light-dependent reactions?

    • Starch, stored in the thylakoid membranes
    • Glucose, made from carbon dioxide in the thylakoid
    • ATP, from ADP and phosphate
    • Oxygen, made by respiration of glucose

  6. What is reduced NADP used for in the Calvin cycle?

    • Breaking down glucose in respiration
    • Splitting water to release oxygen
    • Building the cell wall of the chloroplast
    • Supplying hydrogen to reduce GP to GALP

  7. Which statement best describes the role of chlorophyll in the light-dependent reactions?

    • Chlorophyll fixes carbon dioxide into glucose
    • Chlorophyll breaks down ATP to release energy
    • Chlorophyll absorbs light energy and uses it to excite electrons
    • Chlorophyll is used up as a reactant in the Calvin cycle

  8. A student sees oxygen bubbles released from pondweed in bright light, but none in the dark. What explains this?

    • Oxygen is released by photolysis, which only occurs in the presence of light
    • Oxygen is released from carbon dioxide during the dark reactions
    • Pondweed releases oxygen all the time, so the result is an error
    • Oxygen is produced by respiration, which only occurs in the dark

  9. Why is ATP made in the light-dependent reactions described as photophosphorylation?

    • Water is phosphorylated to form oxygen
    • Phosphate is removed from ATP to release light
    • Phosphate is added to ADP using light-driven energy
    • Glucose is phosphorylated to form starch

  10. In a calculation, 4 electrons are needed to reduce 2 NADP molecules. How many water molecules must be photolysed to supply these electrons?

    • 4
    • 1
    • 8
    • 2

  11. Why do light-dependent reactions require a supply of ADP and inorganic phosphate?

    • They are the products that are released as oxygen
    • They are the pigments that absorb light
    • They are substrates for making ATP
    • They are the enzymes that split water

  12. Which change is seen in a chloroplast when light is removed from the thylakoids for a long time?

    • Chlorophyll is converted into glucose directly
    • Oxygen production rises as a result of the darkness
    • ATP and reduced NADP supply falls, slowing the Calvin cycle
    • Photolysis increases to compensate for the lost light

  13. Which process is coupled to the electron transport chain in the thylakoid?

    • Synthesis of cellulose in the cell wall
    • Pumping hydrogen ions into the thylakoid space
    • Breakdown of starch into maltose
    • Conversion of glucose into carbon dioxide

  14. In photosynthesis, what is the main function of the photosystems?

    • To fix carbon dioxide into glucose in the stroma
    • To break down starch into glucose in the cytoplasm
    • To capture light and pass on excited electrons
    • To make cellulose microfibrils for the cell wall

  15. A plant under strong light makes more ATP. Which reaction is most directly responsible?

    • Respiration of glucose in the mitochondria
    • Photophosphorylation in light-dependent reactions
    • Transpiration of water through stomata
    • Hydrolysis of cellulose in the cell wall

  16. Which evaluation of the light-dependent reactions is correct?

    • They take place only in the dark
    • They produce glucose directly without any further steps
    • They make no contribution to oxygen production
    • They supply ATP and reduced NADP for the Calvin cycle

  17. Why does photolysis of water help to maintain the electron supply in chloroplasts?

    • It replaces electrons lost from chlorophyll
    • It stores electrons in starch granules
    • It removes electrons from ATP to make glucose
    • It converts carbon dioxide into electrons

  18. A student measures the rate of oxygen production by a plant under different light intensities. Which is the best control variable?

    • The temperature of the water containing the plant
    • The light intensity, which is the independent variable
    • The number of days the plant is grown
    • The volume of oxygen produced, which is the dependent variable

  19. Photolysis of 36 water molecules releases how many molecules of oxygen?

    • 72
    • 9
    • 36
    • 18

  20. Which pigment absorbs red and blue light most strongly in chloroplasts?

    • Cellulose in the stroma
    • Chlorophyll
    • Carotene in the stroma
    • Starch in the grana

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