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Standard XII

Biology

Secondary Growth in Stem

Assertion :Th...

Question

Assertion :The phloem present in the xylem elements is called protophloem. Reason: The phloem elements develop in the middle of xylem elements are secondary in nature.

Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

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Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.

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Assertion is correct but Reason is incorrect.

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Assertion is incorrect but Reason is correct.

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Solution

The correct option is D Assertion is incorrect but Reason is correct.
Protophloem is the first formed phloem which has thin walled cells. It is formed from procambium. Therefore, assertion is incorrect.
During secondary growth the vascular cambium gives rise to xylem and phloem cells. There are different types of arrangement of xylem and phloem. One of such arrangement is amphivasal, in which the phloem is in the center and xylem surrounds it from all sides. Therefore, reason is correct.
Thus, the correct answer is option D.

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