Bird's embryo is covered with

Options

A. amnion
B. chorion & allantois
C. yok sac
D. all of these

Answer

To answer the question "Bird's embryo is covered with", we will analyze the different components that surround a bird's embryo and their functions.

### Step-by-Step Solution:

1. **Understanding the Embryo**: The bird's embryo is a product of sexual reproduction and develops through a process called embryogenesis. During this process, various structures form around the embryo, known as extra embryonic membranes.

2. **Identifying Extra Embryonic Membranes**: The main extra embryonic membranes associated with a bird's embryo include:
- **Amnion**: This membrane surrounds the embryo and serves as a protective cushion. It protects the embryo from mechanical stress and temperature fluctuations, while also keeping it moist to prevent dehydration.
- **Chorion**: This is another protective layer that surrounds the embryo, similar to the amnion.
- **Allantois**: This structure is rich in blood vessels and plays a crucial role in gas exchange and the excretion of nitrogenous waste (uric acid) from the embryo.
- **Yolk Sac**: This sac contains yolk, which serves as the nutritional source for the developing embryo.

3. **Conclusion**: All of these membranes (amnion, chorion, allantois, and yolk sac) cover and support the bird's embryo during its development. Therefore, the correct answer to the question is "all of these".

### Final Answer:
Bird's embryo is covered with all of these (amnion, chorion, allantois, and yolk sac).

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