A scientist wants to find out whether the poison made in the leaves of a plant deters slugs from feeding on it.
She has 20 plants of variety A, which makes the poison, and 20 plants of variety B, which does not make the poison. The two varieties are identical in every other way.
Describe a method the scientist could use to find out whether the poison deters slugs.
Give two variables the scientist must control.
The mean area of leaf eaten was 12 cm2 for variety A and 30 cm2 for variety B.
Calculate the percentage decrease in the mean area of leaf eaten for variety A compared with variety B.
Suggest one reason why the scientist should repeat the whole investigation using slugs from a different population.
58 exam-style questions on AQA GCSE Biology 3.3 Plant disease, covering 3.3.1 Detection and identification of plant diseases and 3.3.2 Plant defence responses. Each one has a worked solution and a mark scheme showing where the marks go.