Lesson 3.5.3.2

3.5.3.2 Net production of consumers and ecosystem productivity Quiz: AQA Biology, Unit 5

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.5.3.2, Net production of consumers and ecosystem productivity: 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. In the equation N = I - (F + R), what does N represent?

    • Net production of consumers
    • Net primary production of plants
    • Number of individuals in a population
    • Gross primary production

  2. In the equation N = I - (F + R), what does I represent?

    • The total biomass of the population
    • The energy in incident light
    • The chemical energy store in ingested food
    • The energy lost in respiration

  3. In the equation N = I - (F + R), what does F represent?

    • Chemical energy absorbed by the gut wall
    • The number of feeding events
    • Chemical energy lost to the environment in faeces and urine
    • The fertiliser applied to the crop

  4. What is primary productivity?

    • The mass of carbon in one plant
    • The rate of decomposition in soil
    • The total number of producers in a community
    • The rate of primary production, measured as biomass in a given area in a given time

  5. What is secondary productivity?

    • The rate of secondary production, measured as biomass produced by consumers in a given area in a given time
    • The energy in plant biomass after respiration
    • The number of consumers in one area
    • The production of oxygen by consumers

  6. A consumer ingests 500 kJ of food. It loses 150 kJ in faeces and urine and 200 kJ in respiration. What is its net production?

    • 50 kJ
    • 150 kJ
    • 500 kJ
    • 350 kJ

  7. A consumer ingests 800 kJ, loses 260 kJ in faeces and urine and 340 kJ in respiration. What is its net production?

    • 400 kJ
    • 540 kJ
    • 200 kJ
    • 100 kJ

  8. A consumer ingests 1000 kJ, loses 400 kJ in faeces and urine and 350 kJ in respiration. What is its net production?

    • 350 kJ
    • 250 kJ
    • 1000 kJ
    • 600 kJ

  9. The NPP of producers in a habitat is 12 000 kJ and the net production of the herbivores that feed on them is 1200 kJ. What is the efficiency of energy transfer?

    • 100%
    • 12%
    • 10%
    • 1%

  10. A consumer has I = 600 kJ, F = 200 kJ and R = 300 kJ. What percentage of its ingested energy becomes net production?

    • 33.3%
    • 50%
    • 16.7%
    • 66.7%

  11. The NPP of producers is 6000 kJ and the net production of a consumer is 300 kJ. What is the efficiency of this energy transfer?

    • 20%
    • 10%
    • 5%
    • 50%

  12. Why is the efficiency of energy transfer between trophic levels less than 100%?

    • Energy is absorbed by the next trophic level without loss
    • Energy is destroyed by the sun as it passes through a food chain
    • Energy is always stored as oxygen
    • Energy is lost in respiration and in material that is not eaten or is egested

  13. Simplifying a food web is one farming practice that increases energy efficiency. What is the purpose of this?

    • It increases respiratory losses in the crop
    • It increases the number of predators
    • It stops photosynthesis in the crop
    • It reduces energy lost to food chains that humans do not use

  14. A farm keeps livestock in warm housing to reduce respiratory losses in a human food chain. Why does this increase efficiency?

    • Less energy is respired to keep the animals warm, so more energy is available as net production
    • Warm housing stops photosynthesis in the grass
    • Warm housing increases the energy in faeces
    • Warm housing increases the number of decomposers

  15. A farmer records that a herbivore's net production is 80 kJ and it ingested 400 kJ. Which is the efficiency of this consumer based on ingested energy?

    • 40%
    • 5%
    • 80%
    • 20%

  16. Which statement correctly describes how energy is lost from a food chain?

    • Energy is recycled at each transfer and does not decrease
    • Energy is lost only when organisms die
    • Energy is lost at each transfer through respiration and waste, so less energy reaches higher trophic levels
    • Energy increases at each transfer through respiration

  17. Why is ecosystem productivity lower at higher trophic levels?

    • Each transfer loses energy in respiration and in material that is not eaten or egested
    • Higher trophic levels absorb energy from the soil
    • Higher trophic levels use more photosynthesis
    • Higher trophic levels have more producers

  18. Which term in N = I - (F + R) represents energy lost through respiration?

    • R
    • N
    • F
    • I

  19. A consumer ingests 2000 kJ and has an efficiency of 15% based on ingested energy. What is its net production?

    • 130 kJ
    • 1700 kJ
    • 300 kJ
    • 15 kJ

  20. How is the efficiency of energy transfer between two trophic levels calculated?

    • (GPP of the first level / respiration of the first level) x 100
    • (Net production of the second level / NPP of the first level) x 100
    • (NPP of the first level / net production of the second level) x 100
    • (Faeces of the consumer / ingested food) x 100

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