Assertion (A): Aquatic animals breathe at a much faster rate compared to most terrestrial animals. Reason (R)…

Question

Assertion (A): Aquatic animals breathe at a much faster rate compared to most terrestrial animals.
Reason (R): The concentration of dissolved oxygen in water is much lower than the concentration of oxygen in air.
(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.

Accepted Answer

## Model Answer **(A) Both A and R are true and R is the correct explanation of A.** The amount of dissolved oxygen in water is fairly low compared to oxygen in air, so aquatic organisms must breathe much faster to obtain sufficient oxygen. *Source: Life Processes, Section 5.3 Respiration* ## Explanation The textbook directly states: *"Since the amount of dissolved oxygen is fairly low compared to the amount of oxygen in the air, the rate of breathing in aquatic organisms is much faster than that seen in terrestrial organisms."* This confirms both A and R are true, and R directly causes A — making option (A) the correct choice. Examiners expect you to link the reason to the assertion explicitly.

Science (086) — AI-generated practice question