Lesson 3.5.4.2

3.5.4.2 Fertilisers and their environmental effects Quiz: AQA Biology, Unit 5

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.5.4.2, Fertilisers and their environmental effects: 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. What is the purpose of applying fertilisers to farmland?

    • To remove excess water from the soil
    • To replace nitrates and phosphates lost when crops are harvested and livestock are removed
    • To increase the amount of carbon dioxide in the air
    • To stop bacteria from fixing nitrogen

  2. What is leaching in the context of fertilisers?

    • Uptake of nitrates by roots through active transport
    • Release of oxygen from water by photolysis
    • Washing of dissolved nitrates out of the soil by rainwater
    • Conversion of nitrate to nitrogen gas

  3. Which is an example of a natural fertiliser?

    • Chlorine gas
    • Carbon dioxide
    • Animal manure
    • Ammonium nitrate granules made in a factory

  4. Eutrophication is caused by excess nutrients in water. Which sequence of events is correct?

    • Algae multiply, light is blocked, aquatic plants die, decomposers use oxygen, and fish die
    • Light increases, algae die, decomposers produce oxygen, and fish multiply
    • Plants grow faster, carbon dioxide falls, and nitrate is removed from the water
    • Fish multiply, oxygen rises, algae die, and light increases

  5. After fertiliser run-off enters a lake, the water becomes low in oxygen. What is the most likely cause?

    • Aerobic decomposers use oxygen while breaking down dead algae
    • Algae release large amounts of carbon dioxide into the water
    • Nitrates are converted to oxygen by denitrification
    • Fish use oxygen faster in the light

  6. Why do nitrates leach more readily from soil than ammonium ions?

    • Nitrates are insoluble and sink to the bottom of the soil
    • Nitrates are gases that escape into the air
    • Ammonium ions are removed by photosynthesis
    • Nitrates are highly soluble and are not held by soil particles, whereas ammonium ions are held more strongly

  7. A farmer applies fertiliser shortly before heavy rain. Which environmental effect is most likely?

    • Increased nitrogen fixation in the soil
    • Reduced rate of photosynthesis in the crop
    • Improved water quality in the river
    • Leaching of nitrates into water and eutrophication

  8. A bag of fertiliser weighs 100 kg and contains 20 kg of nitrogen. What is the percentage of nitrogen in the fertiliser?

    • 50%
    • 2%
    • 20%
    • 80%

  9. Why does eutrophication reduce biodiversity in a freshwater lake?

    • Light is blocked and many plants and animals die because oxygen falls
    • Eutrophication stops all decomposition in the lake
    • Eutrophication makes the lake saltier, which all species need
    • Eutrophication increases the number of species in the lake

  10. Which measure would reduce the risk of leaching from farmland?

    • Ploughing the soil and leaving it bare for the winter
    • Applying a large amount of fertiliser before the autumn rains
    • Burning the crop residues to release nitrates
    • Applying fertiliser in small amounts during the growing season

  11. What is one benefit of artificial fertilisers for food production?

    • They reduce the need for water in the crop
    • They replace lost nutrients quickly and can increase crop yields
    • They fix nitrogen gas directly into the soil without bacteria
    • They make eutrophication impossible

  12. Nitrate leaching can contaminate water supplies. What is the main concern?

    • Nitrate removes all oxygen from the atmosphere
    • Nitrate makes the soil fertile for ever
    • High nitrate levels in drinking water can harm human health
    • Nitrate makes water too cold for fish

  13. Algae die in a lake after eutrophication. What happens to submerged plants as a result?

    • They receive less light for photosynthesis and may die
    • They absorb more carbon dioxide and grow faster
    • They receive more light because algae no longer block it
    • They are unaffected because they are above the algae

  14. Why can phosphate fertilisers contribute to eutrophication in freshwater lakes?

    • Phosphate kills algae directly by reacting with them
    • Phosphate stops decomposers from breaking down dead matter
    • Phosphate is often the nutrient in short supply in freshwater, so extra phosphate allows algal growth
    • Phosphate is a gas that escapes from lakes

  15. Which process is most directly responsible for removing nitrates from a waterlogged soil?

    • Respiration in the roots of the crop
    • Nitrogen fixation in root nodules
    • Photosynthesis in the leaves
    • Denitrification by bacteria under anaerobic conditions

  16. Which statement about natural and artificial fertilisers is correct?

    • Natural fertilisers cannot supply nitrates or phosphates
    • Both can supply nitrates and phosphates, but artificial fertilisers can be applied in controlled amounts
    • Artificial fertilisers always cause less leaching than natural fertilisers
    • Natural fertilisers are made from fossil fuels

  17. Apart from harvesting, which process removes nitrates from farmland soil?

    • Nitrogen fixation in nodules
    • Photosynthesis in the crop
    • Leaching into water
    • Respiration in the roots

  18. Which statement about the use of fertilisers is correct?

    • Excess fertiliser always increases the biodiversity of rivers
    • Fertilisers cannot affect water quality
    • Fertilisers prevent leaching from farmland
    • Excess fertiliser can be washed into rivers and contribute to eutrophication

  19. A river shows an algal bloom. Which nutrient source is most likely?

    • Meltwater from glaciers
    • Fertiliser run-off from nearby fields
    • Carbon dioxide from respiring fish
    • Oxygen dissolved from the atmosphere

  20. Which factor mainly determines how much fertiliser a crop needs?

    • The nutrients removed by harvest and the soil's existing supply
    • The number of fish in the nearest river
    • The distance from the field to the nearest river
    • The colour of the crop leaves only

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