A GM variety of maize has been given a gene from a bacterium. This gene makes the maize produce a substance that kills insect pests. A farmer grew the GM maize and a normal variety of maize in the same field for four years.
Figure shows the mean yield of each variety in each year.
Figure: The mean yield of a GM variety of maize and of a normal variety of maize grown in the same field for four years

Calculate the mean yield of the GM maize over the four years.
Give one conclusion about the effect of the inserted gene on the yield of maize. Use Figure in your answer.
Suggest one reason, other than cost, why some people are concerned about growing this GM maize.
44 exam-style questions on AQA GCSE Biology 6.2 Variation and evolution, covering 6.2.1 Variation, 6.2.2 Evolution, 6.2.3 Selective breeding, 6.2.4 Genetic engineering, and 6.2.5 Cloning. Each one has a worked solution and a mark scheme showing where the marks go.