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Question 6

From Biology HL Paper 1A (May 2025, TZ2)

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  1. Bromothymol blue is an indicator that is initially blue and turns yellow when CO2 is present. Tests were carried out varying the presence of a plant (Elodea canadensis) and a snail (Marisa cornuarietis) in an aquatic environment. What condition would produce a blue colour after sampling the water?

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