Question

Assertion : Fishes respire through gills.
Reason : Counter current flow occurs in gills.

• A. If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
• B. If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
• C. If Assertion is correct but Reason is incorrect.
• D. If Assertion is incorrect but Reason is correct.

Answer 1

The correct option is A

If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.

Option A.

Assertion statement :

1. Gills are used by fish to breathe.
2. Gills have blood capillaries that allow them to absorb oxygen dissolved in water.

Reason statement :

1. When water enters the mouth of a fish, dissolved oxygen is absorbed within and carbon dioxide is released.
2. Gills are thin filamentous structures that are densely packed with blood vessels and are arranged in such a way that blood flows in the opposite direction as water flows across them.
3. This arrangement is known as counter-current flow, and it allows for the most efficient oxygen extraction from water.

Final answer: Both assertion and reason are correct and the reason is the correct explanation of assertion.