Question

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Forelimbs of human and bats are homologous.
Reason R: Forelimbs of humans and bats have similar anatomical structure.
In the light of the above statements, choose the most appropriate answer from the options given below:

• A. A is false but R is true
• B. Both A and R are correct and R is the correct explanation of A
• C. Both A and R are true, but R is not the correct explanation of A
• D. A is true but R is false

Hint:

Homology \(\rightarrow\) Similar anatomy, different functions \(\rightarrow\) Divergent evolution. Analogy \(\rightarrow\) Different anatomy, similar functions \(\rightarrow\) Convergent evolution (e.g., wings of butterfly and bird).

Answer 1

The Correct Option is B

Concept:

• Homology: The relationship between structures derived from a common evolutionary ancestor.

• Homologous structures share a similar basic anatomical plan and embryonic development, though they may perform different functions.

• Examples include the forelimbs of humans, cheetahs, whales, and bats, which all consist of humerus, radius, ulna, carpals, metacarpals, and phalanges.

• Homology indicates divergent evolution.

Step 1: Evaluate Assertion A
Assertion A states that the forelimbs of humans and bats are homologous.
This is true, as they are derived from a common mammalian ancestor.

Step 2: Evaluate Reason R
Reason R states that the forelimbs of humans and bats have a similar anatomical structure.
This is also true, as they share the same arrangement of bones.

Step 3: Determine if R is the correct explanation of A
Homology, by definition, is based on structural and anatomical similarity.
Because their forelimbs share the same fundamental anatomical structure, they are classified as homologous organs.
Thus, R is the correct explanation of A.