A crop has been genetically engineered to make a toxin that kills insect pests. After the crop has been grown in an area for several years, the toxin kills far fewer of the pests. Which statement explains this?
The pests made antibodies against the toxin after eating the crop.
The toxin caused mutations that made all of the pests resistant.
The crop stopped making the toxin because the gene was lost.
Resistant pests survived to breed, so the resistance allele spread.
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.