AIIMS 2003 Botany Pigments Assertion Reason Question

To analyze the given question, we need to evaluate the assertion and the reason separately, then determine their truthfulness and relationship.

Assertion:

Rhoeo leaves contain anthocyanin pigments in epidermal cells.

This statement is true. Rhoeo, commonly known as the Moses-in-the-cradle plant, is known to have vibrant leaves that often display purple or reddish hues due to the presence of anthocyanin pigments in the epidermal cells. These pigments contribute to the coloration of the leaves and can play roles in protection against UV radiation and herbivory.

Reason:

Anthocyanins are accessory photosynthetic pigments.

This statement is false. While anthocyanins are indeed pigments found in many plants, their primary role is not as accessory photosynthetic pigments. Accessory pigments, such as chlorophyll b, carotenoids, and xanthophylls, assist in photosynthesis by capturing light energy and transferring it to chlorophyll a for use in the photosynthetic process. Anthocyanins, on the other hand, are more involved in providing coloration, attracting pollinators, and protecting the plant from environmental stress, rather than directly participating in photosynthesis.

Evaluation of Options:

Given our analysis:

• Option A: Both Assertion and Reason are true and Reason is the correct explanation of Assertion.

  • Incorrect: While the assertion is true, the reason is false, thus making this option incorrect.

• Option B: Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

  • Incorrect: The assertion is true, but the reason is false, so this option cannot be correct.

• Option C: Assertion is true but Reason is false.

  • Correct: The assertion is valid as Rhoeo leaves contain anthocyanins, while the reason is false because anthocyanins do not function as accessory photosynthetic pigments.

• Option D: Both Assertion and Reason are false.

  • Incorrect: The assertion is true, so this option cannot be right.

Conclusion:

The correct answer is C because the assertion about Rhoeo leaves containing anthocyanins is true, while the reason regarding anthocyanins being accessory pigments is false. This illustrates the importance of distinguishing between different types of pigments and their roles in plant physiology.

Key Concepts:

• Anthocyanins: Water-soluble pigments that can appear red, purple, or blue depending on the pH, primarily serving protective roles in plants.
• Accessory Pigments: Pigments that assist in photosynthesis by capturing light energy, such as chlorophyll b and carotenoids.

Understanding these distinctions is crucial in the study of plant physiology and botany, especially when preparing for exams like NEET or JEE.