Question

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Lobe finned fishes can grip food items and slice them.
Reason (R) : Gnathostomes are 'jaw-mouth' animals.
In the light of the above statements, choose the most appropriate answer from the options given below :

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

Hint:

In evolutionary biology questions, look for the defining morphological trait. Jaws (Gnathostomata) revolutionized feeding by allowing predation and biting. The Assertion uses a specific animal group (Lobe-finned fish) to test if you know they belong to that broader, jaw-possessing classification.

Answer 1

The Correct Option is A

Step 1: Concept:
This question tests zoological taxonomy and evolutionary biology, specifically the functional advantages acquired by early vertebrates with the evolution of jaws.

Step 2: Step-by-step Explanation:

• Evaluating Reason (R): The superclass "Gnathostomata" literally translates from Greek as "jaw-mouth" (gnathos = jaw, stoma = mouth). It encompasses all jawed vertebrates. This is a fundamental, correct definition.

• Evaluating Assertion (A): Lobe-finned fishes (Sarcopterygii) are an advanced group of bony fishes. As members of the Gnathostomata superclass, they possess hinged jaws and teeth. Before the evolution of jaws, jawless vertebrates (Agnathans) were largely restricted to suction feeding or scavenging. The evolutionary acquisition of jaws gave Gnathostomes the mechanical ability to actively bite, firmly grip struggling prey, and slice food items into manageable pieces. Therefore, stating that a subset of jawed fishes (lobe-finned fishes) can grip and slice food is factually correct.

• Relationship: Why can lobe-finned fishes grip and slice food? Because they are jawed vertebrates (Gnathostomes). The presence of the jaw (as defined in R) provides the exact structural mechanism required for the action described in (A). Thus, R is the correct biological explanation for A.

Step 3: Final Answer:
Both statements are true and correctly linked by cause and effect. This points to option (A).