Who is responsible for the sex of the chicks ?

Options

A. sperm
B. egg
C. temperature
D. hormones

Answer

**Step-by-Step Solution:**

1. **Understanding Sex Determination in Birds:**
- In birds, the mechanism of sex determination is based on female heterogamety. This means that the female birds have two different types of sex chromosomes.

2. **Identifying the Gametes Produced by Females:**
- Female birds produce two types of gametes: one with a Z chromosome and one with a W chromosome. Therefore, the female is heterogametic (ZW).

3. **Identifying the Gametes Produced by Males:**
- Male birds, on the other hand, are homogametic and produce only one type of gamete, which is the Z chromosome (ZZ).

4. **Conclusion on Who Determines the Sex of Chicks:**
- Since the female produces two types of gametes (Z and W), and the male produces only one type (Z), it is the female's egg that determines the sex of the chicks. If the egg carries a Z chromosome, the offspring will be male (ZZ), and if it carries a W chromosome, the offspring will be female (ZW).

5. **Analyzing the Options Given:**
- Option 1 (sperm) is incorrect because males produce only Z gametes.
- Option 2 (egg) is correct because females produce both Z and W gametes.
- Option 3 (temperature) and Option 4 (hormones) are also incorrect in the context of sex determination in birds.

6. **Final Answer:**
- The correct answer is that the egg is responsible for the sex of the chicks.

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