Use limiting factor reasoning
A pondweed practical in a plant growth investigation increases light intensity, but the photosynthesis rate stops rising when carbon dioxide becomes scarce. Identify the limiting factor at the plateau. Enter the answer and choose the interpretation that best matches the biological evidence.
Worked practice: biological evidence and answer
Use the labelled biological evidence first, then connect it to the final answer.
Write a full answer
Now write the response in full, in your own words — this is what the exam asks for. The AI marks it on the same moves you built above (focus, evidence, technique, judgement) and gives feedback on reasoning, evidence, and expression.