In which of the following organism , males are heterogametic and have chromosome number different than females ?

Options

A. Drosophila
B. Human
C. Birds
D. Bugs

Answer

To solve the question regarding which organism has males that are heterogametic and have a different chromosome number than females, we can analyze each option step by step.

### Step 1: Understand Heterogametic Males
Heterogametic males are those that have two different sex chromosomes. For example, in humans and Drosophila, males have XY chromosomes, while females have XX chromosomes. In contrast, homogametic males have the same sex chromosomes (e.g., ZZ in birds).

### Step 2: Analyze Each Organism
1. **Drosophila (Fruit Fly)**:
- Male genotype: XY
- Female genotype: XX
- Conclusion: Males are heterogametic (XY) and have a different chromosome number than females (2 vs. 2).

2. **Humans**:
- Male genotype: XY
- Female genotype: XX
- Conclusion: Males are heterogametic (XY) and have a different chromosome number than females (2 vs. 2).

3. **Birds**:
- Male genotype: ZZ
- Female genotype: ZW
- Conclusion: Males are not heterogametic (ZZ), females are heterogametic (ZW).

4. **Bugs (Insects)**:
- Male genotype: XO (one X chromosome)
- Female genotype: XX (two X chromosomes)
- Conclusion: Males are heterogametic (XO) and have a different chromosome number than females (1 vs. 2).

### Step 3: Determine the Correct Answer
From the analysis:
- Drosophila: Males are heterogametic, but chromosome number is the same.
- Humans: Males are heterogametic, but chromosome number is the same.
- Birds: Males are not heterogametic.
- Bugs: Males are heterogametic and have a different chromosome number than females.

Thus, the correct answer is **Bugs**.

### Final Answer:
**Bugs** (Option D) are the organisms where males are heterogametic and have a different chromosome number than females.

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