Question

Assertion (A) : In large animals, oxygen can reach different parts of the animal's body easily.
Reason (R) : Respiratory pigments take up oxygen from the air and carry it to body tissues.

• A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
• B. Both Assertion (A) and Reason (R) are true and Reason (R) is not the correct explanation of Assertion (A).
• C. Assertion (A) is true, but Reason (R) is false.
• D. Assertion (A) is false, but Reason (R) is true.
  {5pt}

Answer 1

The Correct Option is D

Assertion (A): In large animals, oxygen cannot reach different parts of the animal's body "easily" just by simple diffusion from the surface. The surface area to volume ratio is too small, and diffusion distances are too large for efficient oxygen supply to all cells. Specialized respiratory and circulatory systems are required. So, the statement "easily" makes the assertion false. Reason (R): Respiratory pigments (like hemoglobin in vertebrates or hemocyanin in some invertebrates) bind to oxygen in areas of high oxygen concentration (e.g., lungs, gills) and release it in areas of low oxygen concentration (body tissues). They play a crucial role in transporting oxygen. This statement is true. Explanation: Assertion (A) is false because oxygen transport in large animals is a complex process, not "easy" by simple means. Reason (R) is a true statement about how oxygen is transported, which is precisely why such pigments are needed in large animals where simple diffusion is insufficient. The reason highlights a mechanism that makes oxygen transport possible but doesn't support the idea that it's "easy" without these mechanisms. \[ \boxed{\text{Assertion (A) is false, but Reason (R) is true.}} \]