Lesson 3.5.1.2

3.5.1.2 Photosynthesis: limiting factors and investigation Quiz: AQA Biology, Unit 5

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.5.1.2, Photosynthesis: limiting factors and investigation: 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. Which environmental factor directly acts as a limiting factor for photosynthesis?

    • Carbon dioxide concentration
    • Soil pH
    • Oxygen concentration
    • Glucose concentration

  2. In a well-lit greenhouse, how can a grower further increase the rate of photosynthesis?

    • Increase CO2 concentration
    • Increase oxygen concentration
    • Reduce humidity
    • Decrease temperature

  3. What defines a limiting factor in a physiological process like photosynthesis?

    • Increases energy loss
    • Stops all activity
    • Destroys required enzymes
    • Restricts process rate

  4. When increasing light intensity no longer increases photosynthesis rate, what has occurred?

    • Light reaction stops
    • Another factor limits
    • Chlorophyll is destroyed
    • Stomata open fully

  5. Which commercial practice increases carbon dioxide concentration in greenhouses?

    • Burning propane heaters
    • Overhead spraying
    • Adding nitrate fertiliser
    • Installing LED lamps

  6. Which technique is used to separate photosynthetic pigments from leaves?

    • Chromatography
    • Electrophoresis of proteins
    • Titration
    • Serial dilution

  7. How is the Rf value of a photosynthetic pigment calculated?

    • Pigment distance / solvent distance
    • Pigment distance / origin distance
    • Solvent distance / pigment distance
    • Origin distance / pigment distance

  8. What difference between shade-tolerant and sun-adapted leaves is shown by chromatography?

    • Glucose solubility
    • DNA sequence
    • Pigment proportions
    • Number of stomata

  9. Which redox indicator is commonly used to measure dehydrogenase activity in isolated chloroplasts?

    • Iodine solution
    • DCPIP
    • Benedict's reagent
    • Biuret reagent

  10. When investigating DCPIP decolourisation rate at different light intensities, what is the independent variable?

    • Light intensity
    • Volume of DCPIP
    • Chloroplast concentration
    • Time to decolourise

  11. What limits the rate of photosynthesis when carbon dioxide concentration is increased to high levels?

    • Light or temperature
    • Stomatal density
    • Chloroplast density
    • Carbon dioxide

  12. What is the most suitable dependent variable when measuring oxygen production by aquatic pondweed?

    • Volume of oxygen
    • Light intensity
    • Carbon dioxide concentration
    • Temperature

  13. Why is the rate of photosynthesis low at low temperatures?

    • Reduced kinetic energy
    • Stomata are closed
    • Enzymes are denatured
    • Chlorophyll is destroyed

  14. If increasing light and carbon dioxide does not increase photosynthesis rate, what factor should be increased?

    • Oxygen level
    • Temperature
    • Water supply
    • Chlorophyll count

  15. How is light intensity varied when investigating photosynthesis rate using an aquatic plant?

    • Changing lamp distance
    • Changing temperature
    • Adding sodium hydrogencarbonate
    • Using different lamps

  16. Why must temperature be controlled during an investigation into the effect of light intensity on photosynthesis?

    • Alters light wavelength
    • Degrades chlorophyll
    • Changes water pH
    • Affects enzyme activity

  17. What happens to the rate of photosynthesis as light intensity increases when light is limiting?

    • It decreases
    • It increases
    • It remains constant
    • It fluctuates

  18. Which variable must be controlled when measuring photosynthesis rate by temperature?

    • Carbon dioxide concentration
    • Enzyme concentration
    • Temperature
    • Product volume

  19. Why does the rate of photosynthesis decrease at temperatures above the optimum?

    • ATP production stops
    • Enzymes are denatured
    • Stomata open fully
    • Chlorophyll breaks down

  20. What does a faster colour change of a redox indicator in chloroplast suspension indicate?

    • Lower respiration rate
    • Higher rubisco concentration
    • Lower photosynthetic rate
    • Higher dehydrogenase activity

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