Which of the following structures are homologues

Options

A. Dorsal fin a Shark
B. Wing of a Moth
C. Hind limb of Rabbit
D. Flipper of Whale

Answer

To determine which of the given structures are homologous, we need to understand the definitions of homologous and analogous structures:

1. **Homologous Structures**: These are structures that have a common evolutionary origin but may serve different functions in different species. They indicate a shared ancestry.

2. **Analogous Structures**: These are structures that serve similar functions but do not share a common evolutionary origin. They arise due to convergent evolution, where different species adapt to similar environments.

Now, let's analyze the given structures one by one:

### Step 1: Analyze the Dorsal Fin of a Shark
- **Description**: The dorsal fin of a shark is a structure found in aquatic creatures.
- **Analysis**: This fin serves the same function (stability in water) across different species living in similar habitats (aquatic).
- **Conclusion**: This is an **analogous structure**.

### Step 2: Analyze the Wings of a Moth
- **Description**: The wings of a moth are used for flying.
- **Analysis**: Moths and butterflies have different evolutionary origins, but their wings serve the same function (flight).
- **Conclusion**: This is also an **analogous structure**.

### Step 3: Analyze the Hindlimb of a Rabbit
- **Description**: The hindlimb of a rabbit is used for locomotion.
- **Analysis**: While the hindlimb of a rabbit and that of a frog serve similar functions (movement), they come from different evolutionary backgrounds (rabbit is a mammal, frog is an amphibian).
- **Conclusion**: This is an **analogous structure**.

### Step 4: Analyze the Flippers of a Whale
- **Description**: The flippers of a whale are used for swimming.
- **Analysis**: The flippers are structurally similar to the forelimbs of humans, indicating a common ancestry. Despite their different functions (swimming vs. manipulation), they share a similar structural framework.
- **Conclusion**: This is a **homologous structure**.

### Final Conclusion
Based on the analysis, the only homologous structure among the options provided is the **flippers of a whale**.

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