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AQA Biology: A Level. Scientists suggest that the mutant plants producing more chlorophyll b would grow faster than normal plants in all light intensities. Explain how (4 marks) Scientists are investigating the effects of a mycorrhizal fungus on growth of pea plants. Explain why they sterilized the surfaces of the seeds and grew them in soil ...
Questions and model answers on 5.3 Energy & Ecosystems (A Level only) for the AQA A Level Biology syllabus, written by the Biology experts at Save My Exams.
Negative feedback could come up as an essay question in the exam so make sure you know several examples and can explain how each work! Control of Negative Feedback. Negative feedback loops help maintain a normal range or balance within an organism. They reduce the initial effect of the stimulus.
1. Positive correlation between sucrose and dopamine concentrations / higher concentration of sucrose, more dopamine; NB question is ‘How do these ...’, not ‘Do these .... Ignore simple statements of numbers from graph without description of trend. So (dopamine) makes them want to drink / eat more (sucrose);
Positive feedback amplifies changes, accelerating the system away from its equilibrium. Negative feedback counteracts changes, pushing the system back towards its equilibrium. In homeostasis context, positive feedback could be labour where contractions become stronger until a baby is delivered.
Six-mark questions. Understanding how to approach exam questions helps to boost exam performance. Question types will include multiple choice, structured, mathematical and practical questions ...
Past paper questions for the Principles of Homeostasis and Negative Feedback topic of A-Level AQA Biology.
