Lesson 5.3.1

5.3.1 Primary productivity and transfer efficiency between trophic levels 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 5.3.1, Primary productivity and transfer efficiency between trophic levels: 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. What is gross primary productivity (GPP)?

    • The total rate at which plants fix energy by photosynthesis
    • The energy left after plant respiration is subtracted
    • The energy transferred to herbivores by feeding
    • The energy lost as heat from the soil

  2. What is net primary productivity (NPP)?

    • The energy stored in plant biomass after respiratory losses
    • The total energy fixed by photosynthesis before any losses
    • The energy transferred to the next trophic level
    • The energy released by respiration in animals

  3. Which equation links gross and net primary productivity?

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

  4. What is the formula for the efficiency of energy transfer between trophic levels?

    • (energy transferred to the next level / energy available at the previous level) x 100
    • (energy transferred x energy available) / 100
    • (energy available at the previous level / energy transferred to the next level) x 100
    • (energy lost as heat / total energy) x 100 only

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

    • 14000 kJ
    • 6000 kJ
    • 10000 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?

    • 3500 kJ
    • 2000 kJ
    • 1500 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. Why is energy transfer between trophic levels typically inefficient?

    • Energy is stored permanently in the cell walls of plants
    • Energy is lost as heat and as uneaten material
    • Energy passes unchanged through every trophic level
    • Energy is destroyed in the chloroplast during photosynthesis

  9. Which of these is a loss of energy from a trophic level that reduces transfer efficiency?

    • Energy passed to the next level in the food
    • Energy stored in new body tissue
    • Energy released in photosynthesis
    • Heat lost in respiration

  10. Why does primary productivity matter for the whole ecosystem?

    • It sets the energy available to all consumers
    • It determines the number of species that can be named
    • It controls the abiotic temperature of the habitat only
    • It removes energy from the ecosystem permanently

  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?

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

  12. Why is a food chain usually limited to four or five trophic levels?

    • Plants are unable to make food at higher levels
    • Little energy reaches each higher level
    • Predators always die when they reach a higher level
    • Energy increases at each higher level

  13. A student compares two habitats. Habitat A has higher NPP per square metre than habitat B. Which conclusion is best supported?

    • Habitat B has higher GPP per unit area
    • Habitat A stores more energy as plant biomass
    • Habitat A has more herbivores in every case
    • Habitat A has no respiration

  14. Which factor could increase primary productivity in a habitat?

    • Lowered carbon dioxide availability in the air
    • Removal of all producers from the habitat
    • Increased availability of light, water and mineral ions
    • Increased respiration rates in the producers

  15. Which statement about the carbon cycle and productivity is correct?

    • Productivity is unrelated to the carbon cycle
    • Carbon dioxide is fixed into biomass by photosynthesis and returned by respiration
    • Carbon is removed from the cycle by respiration only
    • Carbon dioxide is destroyed by photosynthesis, so it is no longer part of the cycle

  16. Which method could reduce atmospheric carbon dioxide according to knowledge of the carbon cycle?

    • Clearing forests to reduce the amount of biomass
    • Reforestation, storing carbon as plant biomass
    • Burning more fossil fuels to speed up photosynthesis
    • Reducing the number of plants to decrease respiration

  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?

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

  18. Why does a farmer grow crops rather than rear animals to feed people in a more energy-efficient way?

    • Eating plants skips energy losses between levels
    • Crops have no respiratory losses at all
    • Animals always produce more energy than plants
    • Animals cannot be fed to people under any conditions

  19. Which statement best explains why NPP may be lower in a crop field than in a natural forest?

    • Forests cannot store energy as biomass
    • Crops have no respiration, so NPP should be higher
    • Harvest removes stored biomass and its energy
    • Crop fields have no photosynthesis at all

  20. A student says transfer efficiency should be calculated from numbers of organisms rather than energy. What is the best evaluation?

    • Energy is needed, as numbers ignore energy content
    • Numbers of organisms are always the most accurate measure of efficiency
    • Energy and numbers always give the same efficiency
    • Transfer efficiency cannot be measured at all

All Pearson Edexcel Biology A (Salters-Nuffield) quizzes