A student investigated the effect of magnesium ions on the colour of tomato leaves. The student grew 10 tomato seedlings in a complete growing solution and 10 tomato seedlings in a growing solution that contained no magnesium ions. After three weeks the student recorded the colour of the leaves of every plant.
Give the independent variable in this investigation.
Give one variable that the student should have controlled.
Explain why the student grew 10 seedlings in each group rather than one seedling in each group.
Predict the colour of the leaves of the plants grown in the solution containing no magnesium ions.
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.