Fertilisers and eutrophication Quiz
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5 questions, one answer each
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1. Which process directly removes nitrate and phosphate ions from a field when a crop is harvested?
- A. Leaching of ions by rain
- B. Removal of the ions in the biomass of the crop
- C. Denitrification by soil bacteria
- D. Decomposition by saprobionts
2. Why is leaching more likely after artificial fertiliser than after manure?
- A. Artificial fertiliser is insoluble
- B. Manure contains no nitrogen
- C. The nitrate in artificial fertiliser is already soluble
- D. Manure is heavier so it is washed away
3. What is the first effect of nitrate and phosphate entering a lake?
- A. Fish die
- B. Rapid growth of algae
- C. Oxygen concentration rises
- D. Saprobionts disappear
4. Why does the oxygen concentration of a eutrophic lake fall?
- A. Algae stop respiring
- B. Fish release carbon dioxide
- C. Saprobionts use oxygen decomposing dead plants and algae
- D. Nitrate reacts with dissolved oxygen
5. Trials show 150 kg per hectare of fertiliser gives a yield of 44 tonnes per hectare and 250 kg gives 45. What is the best conclusion?
- A. Apply 250 kg because it gives the highest yield
- B. Apply about 150 kg because the extra yield from 250 kg is small and increases the risk of leaching
- C. Apply no fertiliser
- D. Fertiliser has no effect on yield