Question

Select the correct option-
Assertion: When there is a deficiency of relatively mobile elements, the deficiency symptoms appear first in young tissues.
Reason: Relatively mobile elements like nitrogen, phosphorus etc are transported from young tissues to old senescing tissues

• A. Both assertion & reason are correct and the reason is the correct explanation of assertion.
• B. Both assertion & reason are correct but the reason is not the correct explanation of assertion.
• C. Assertion is correct but the reason is incorrect
• D. Both assertion & reason are incorrect

Answer 1

The correct option is D Both assertion & reason are incorrect

Relatively mobile elements in plants are nitrogen, potassium and magnesium. These elements can be actively mobilised from the older to young developing tissues or leaves, so the deficiency symptoms tend to appear first in the older leaves.

An element like calcium which contribute to the structural make up of the plant is an immobile element. Thus it cannot be remobilized easily from the older leaves to the younger leaves. So the deficinency symptoms appear in the young leaves in this case.
Hence the assertion and reasoning are both incorrect.