Photosynthesis — O/L Science

How do I practise Photosynthesis?

1 question with a worked solution · 6 marks

1. 2023 · Paper II · 6 marks
   Question 4 describes a destarched green leaf kept in the dark, then illuminated, then tested for starch with iodine. It asks you what result to expect and why, to write the word equation for photosynthesis, and to name two factors that limit the rate of photosynthesis in a plant kept indoors.
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   (i) The iodine solution turns BLUE-BLACK where starch is present — expected in the illuminated leaf because the plant performed photosynthesis during the 6 hours of light, producing and storing starch. (ii) Carbon dioxide + Water → (light energy) → Glucose + Oxygen (iii) Low light intensity; low carbon dioxide concentration (temperature could also be limiting if indoor temp is low).
   Source: Department of Examinations, Sri Lanka — G.C.E. O/L Science 2023, Paper II, Question 4 · https://doenets.lk/pastpapers

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