More people can be fed from an area of land if they eat crops, rather than meat from animals fed on those crops. Which statement explains why?
Crops contain more protein than meat, so less food is needed each day.
Energy is lost at each trophic level, so less is passed on to people.
Animals photosynthesise less efficiently than the crops they are fed.
Crops grown for people need less fertiliser than crops for animals.
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.