Lesson 5.3.1

5.3.1 Primary productivity and transfer efficiency between trophic levels Quiz: Pearson Edexcel Biology, Unit 5

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 5.3.1, Primary productivity and transfer efficiency between trophic levels: 20 multiple choice questions for the Pearson Edexcel Biology (9BI0), Unit 5: On the Wild Side, written with Revision Ninja.

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The 20 questions

  1. What term describes the total rate at which chemical energy is fixed by autotrophs?

    • Biomass transfer
    • Respiratory loss
    • Gross primary productivity
    • Net primary productivity

  2. Which equation correctly defines net primary productivity (NPP)?

    • NPP = R - GPP
    • NPP = GPP / R
    • NPP = GPP + R
    • NPP = GPP - R

  3. Which equation links gross and net primary productivity?

    • NPP = GPP x respiration
    • NPP = GPP - respiration
    • NPP = GPP + respiration
    • NPP = respiration / GPP

  4. How is energy transfer efficiency between trophic levels calculated?

    • (Energy input ÷ output) × 100
    • (Energy loss ÷ input) × 100
    • (Energy output ÷ input) × 100
    • (Energy output ÷ loss) × 100

  5. A producer fixes 10000 kJ of energy in a year and respires 4000 kJ. What is its NPP?

    • 10000 kJ
    • 6000 kJ
    • 14000 kJ
    • 4000 kJ

  6. A herbivore takes in 5000 kJ of plant material. It is measured to lose 2000 kJ as faeces and 1500 kJ as respiratory heat. What energy is available for growth and reproduction?

    • 2000 kJ
    • 1500 kJ
    • 3500 kJ
    • 5000 kJ

  7. A producer level receives 20000 kJ of energy from sunlight, and the next level receives 2000 kJ. What is the transfer efficiency?

    • 50%
    • 20%
    • 10%
    • 1%

  8. Which factor causes energy loss between trophic levels?

    • Increased photosynthesis
    • Respiration heat loss
    • Carbon dioxide fixation
    • DNA replication

  9. Which process directly reduces the energy available to the next trophic level?

    • Photosynthetic fixation
    • Excretion and egestion
    • Glucose synthesis
    • Biomass accumulation

  10. What determines the total energy available to all consumers in an ecosystem?

    • Secondary productivity
    • Primary productivity
    • Decomposition rate
    • Trophic inefficiency

  11. A calculation shows a herbivore converts 100 kJ of food into 15 kJ of body growth. What is the efficiency of conversion of ingested food to growth?

    • 0.15%
    • 15%
    • 100%
    • 85%

  12. What limits the length of a food chain to four or five trophic levels?

    • Energy loss
    • Primary succession
    • Interspecific competition
    • Bioaccumulation

  13. What does higher net primary productivity (NPP) in a habitat indicate?

    • Less absorbed light
    • More biomass stored
    • Higher respiration rate
    • Lower gross productivity

  14. Which change would directly increase primary productivity in a habitat?

    • Decreased soil nitrates
    • Increased light intensity
    • Reduced carbon dioxide
    • Increased respiration

  15. Which process fixes carbon dioxide into organic biomass in the carbon cycle?

    • Combustion
    • Decomposition
    • Respiration
    • Photosynthesis

  16. Which process reduces atmospheric carbon dioxide by storing carbon in plant biomass?

    • Reforestation
    • Crop harvesting
    • Deforestation
    • Biomass combustion

  17. A calculation: a rabbit population gains 300 kJ from 3000 kJ of plant material eaten. What is the percentage of energy from food that is converted into growth?

    • 10%
    • 30%
    • 3%
    • 100%

  18. Why is producing plant crops for human food more energy efficient than rearing livestock?

    • Lower primary productivity
    • Increased bioaccumulation
    • Higher respiration losses
    • Fewer trophic levels

  19. Why is energy removed from an agricultural ecosystem during crop harvesting?

    • Respiration stops
    • Photosynthesis increases
    • Biomass is removed
    • Succession occurs

  20. Why are energy values preferable to numbers of organisms when calculating transfer efficiency?

    • Trophic levels overlap
    • Numbers are constant
    • Energy cannot measure
    • Organism size varies

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