Radish seedlings were grown in a nutrient solution lacking magnesium ions. The seedlings developed yellow leaves and gained little dry mass. Magnesium ions were then added to the nutrient solution.
Why did the seedlings begin to gain dry mass more quickly?
The magnesium increased respiration, releasing more energy for photosynthesis.
The magnesium killed pathogens, preventing further yellowing of the leaves.
The magnesium was used to make chlorophyll, increasing the rate of photosynthesis.
The magnesium was converted into glucose, providing material for new cells.
133 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.