Question

Given below are two statements, one is labelled as Assertion (A) and the other one labelled as Reason (R).
Assertion (A): Sulphur deficiencies first appear on the younger growth in the plants.
Reason (R): Sulphur is mobile in the plants, thereby, fading the normal green colour of the young leaves.
In light of the above statements, choose the correct answer from the options given below.

• A. Both (A) and (R) are true and (R) is the correct explanation of (A).
• B. Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

Recall whether sulphur can move back out of older leaves.

Answer 1

The Correct Option is C

This is an assertion and reason question, so we need to check the assertion, check the reason, and then see if the reason actually explains the assertion.

1. Checking Assertion (A): sulphur deficiency does show up first on the youngest leaves of a plant, because young tissue is starved of the sulphur it needs to build chlorophyll and key amino acids. This part is true.
2. Checking Reason (R): the claim that sulphur is mobile inside the plant is not true. Sulphur behaves like an immobile nutrient once it is fixed into plant tissue, so it cannot be shifted back out of old leaves the way nitrogen or potassium can.

Since sulphur cannot move out of the old leaves, those older leaves keep their supply and stay green, while the young leaves, which depend on fresh uptake from the soil, turn pale first. So the real reason behind the assertion is immobility, the exact opposite of what statement (R) claims.

Let's summarize:

• Assertion (A) is a correct fact about where sulphur deficiency shows up.
• Reason (R) gets the mechanism backwards by calling sulphur mobile when it is actually immobile in the plant.

So (A) is true but (R) is false, matching option 3.