A farmer adds a fertiliser containing nitrates to a field of wheat. Why does this increase the yield of wheat?
Plants use nitrates to make proteins needed for growth.
Nitrates kill the insect pests that feed on the plants.
Plants use nitrates as a source of energy for respiration.
Nitrates increase the carbon dioxide taken in by leaves.
127 exam-style questions on OCR GCSE Biology 6.2 Feeding the human race, covering 6.2.1 Biological factors affecting food security, 6.2.2 Agricultural solutions to growing demand, 6.2.3 Selective breeding, 6.2.4 Genetic engineering, 6.2.5 Steps in genetic engineering, 6.2.6 Benefits and risks of gene technology in agriculture, and 6.2.7 Biotechnological solutions to growing demand. Each one has a worked solution and a mark scheme showing where the marks go.