A plant kept in darkness does not show a blue-black colour when iodine is added to its leaf. What is the most correct reason?
Answer and explanation
Correct answer: Starch was not formed in the leaf
The governing concept is the iodine test for starch and the role of light in photosynthesis. Iodine turns blue-black when starch is present. A plant kept in darkness cannot receive the light energy required to drive photosynthesis, so the leaf does not produce enough stored starch for the test. Thus option A is correct. Excess water, absence of xylem and the number of guard cells do not explain the missing iodine colour in this experiment.
Frequently asked questions
What is the correct answer to this question?
Starch was not formed in the leaf
Why is this the correct answer?
The governing concept is the iodine test for starch and the role of light in photosynthesis. Iodine turns blue-black when starch is present. A plant kept in darkness cannot receive the light energy required to drive photosynthesis, so the leaf does not produce enough stored starch for the test. Thus option A is correct. Excess water, absence of xylem and the number of guard cells do not explain the missing iodine colour in this experiment.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: World of Living. Topic: Life Processes.
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