From 1970 to 2010, a farmer in the USA kept 250 cows producing milk on his farm throughout. Use the data in Table 6.1 to calculate how much milk production by 250 cows increased between 1970 and 2010. Give your answer in standard form.
One explanation for the pattern in Table 6.1 is that farmers use artificial selection to breed cows with greater milk output. This is selective breeding. Using this example, describe the main stages in selective breeding.
Outline the stages in the genetic modification process used to make these crop plants.
Genetic modification has also been used to alter crop plants in other ways. One example is crop plants that contain a chemical so that they are resistant to insect pests. Outline two possible risks of growing these crops.