cy and remain at the bottom A1","marks":2,"order":1,"markingRubric":null,"explanation":{"methods":[{"id":"link_cause_to_effect","label":"Link cause to effect","steps":[{"type":"text","order":0,"title":"Identify the blocked process","content":"The inhibitor blocks photosynthesis, so the light-dependent reaction cannot produce oxygen gas. **This earns M1** because it explains why oxygen is no longer made.","highlights":[{"text":"chemical inhibitor was added","location":"specification"}]},{"type":"text","order":1,"title":"Explain why discs stay down","content":"Without oxygen gas filling the intercellular air spaces, the discs do not gain **buoyancy** (an upward force in a liquid), so they remain at the bottom. **This earns A1** because it links the missing oxygen to the discs not rising.","highlights":[{"text":"did not rise to the surface","location":"specification"}]}]}],"generatedAt":"2026-07-22T11:28:56.198Z","modelVersion":"gpt-5.6-terra+diagrams-1","explanationVersion":"v3"},"options":[]},{"id":"6af2d739-db9d-4e23-99f0-4333e0aa9f5a","label":"c","content":"The scientists then investigate how light exposure affects the buoyancy of these leaf discs over time.\n- In **Experiment X**, 10 leaf discs are exposed to 6 hours of light followed by 18 hours of darkness.\n- In **Experiment Y**, 10 leaf discs are exposed to continuous light for 24 hours.\n\nThey record the number of floating leaf discs at regular intervals over a 24-hour period. The results are shown in the graphs below:\n\n![Graph showing the number of floating leaf discs over a 24-hour period for Experiment X and Experiment Y](https://assets.mathsgenie.co.uk/aqa-qb/52d8dcd6-d7e7-4306-88c4-b9ea8ad2bb6b.png)\n\nWhat conclusion can be made from **Experiment X** about the effect of light on the buoyancy of the leaf discs?","markscheme":"- Exposure to light causes the leaf discs to rise/float, while darkness causes them to sink M1\n- There is a slight time lag between switching off the light (at hour 6) and the discs sinking (by hour 8) A1","marks":2,"order":2,"markingRubric":null,"explanation":{"methods":[{"id":"read_experiment_x","label":"Read Experiment X","steps":[{"type":"text","order":0,"title":"State the main pattern","content":"In Experiment X, use the top graph. During the light period, the number of floating discs rises to $10$, so light causes the leaf discs to rise or float. After darkness begins, the number floating falls to $0$, so darkness causes them to sink. This comparison earns **M1**.","highlights":[{"text":"In **Experiment X**, 10 leaf discs are exposed to 6 hours of light followed by 18 hours of darkness.","location":"specification"}]},{"type":"text","order":1,"title":"Add the time lag","content":"The light is switched off at $6$ hours, but the discs do not finish sinking until $8$ hours. Therefore, there is a slight time lag before the discs sink in darkness. This observation earns **A1**.","highlights":[{"text":"6 hours of light followed by 18 hours of darkness","location":"specification"}]}]}],"generatedAt":"2026-07-22T11:36:05.490Z","modelVersion":"gpt-5.6-terra+diagrams-1","explanationVersion":"v3"},"options":[]},{"id":"46b9159f-797a-46ac-9110-ecec6751a658","label":"d","content":"Suggest an explanation for the differences in the number of floating leaf discs between the two experiments after 12 hours.","markscheme":"- At 12 hours, the discs in Experiment X have sunk because they are in darkness, meaning photosynthesis stops and oxygen is no longer produced (and any remaining oxygen is consumed by respiration) M1\n- In Experiment Y, the discs are in continuous light, allowing continuous photosynthesis and sustained oxygen production, which keeps them floating A1","marks":2,"order":3,"markingRubric":null,"explanation":{"methods":[{"id":"link_light_to_floating","label":"Link light to floating","steps":[{"type":"text","order":1,"title":"Explain Experiment X","content":"In Experiment X, after $12$ hours the discs are in darkness. Without light, photosynthesis stops, so no

Photosynthesis

Question 7

Photosynthesis Questions

Photosynthesis

Question 7

Photosynthesis Questions