Advanced Science Primary 6 Energy

Luke kept a plant in a dark cupboard for 48 hours. He then tested a leaf for the presence of starch. What would be the observation and the reason?

A Iodine remains brown; starch was used up for energy
B Iodine turns blue-black; starch was produced in the dark
C Iodine remains brown; photosynthesis occurred without light
D Iodine turns blue-black; starch was stored in the leaves
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Worked Solution

Step 1: Without light, the plant cannot perform photosynthesis to make new food. Step [2-9]: The plant uses its stored starch for energy during the 48 hours. Step [2-9]: The starch test will be negative (iodine stays brown).

Correct answer: Iodine remains brown; starch was used up for energy

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