In angiosperm, all 4 microspores of tetrad are covered by a layer which is formed by

Options

A. Pectocellulose
B. Callose
C. Cellulose
D. Sporopollenin

Answer

**Step-by-Step Solution:**

1. **Understanding Microsporogenesis**: In angiosperms, the process of microsporogenesis begins with microspore mother cells (microsporocytes) undergoing meiosis. This process results in the formation of microspores.

2. **Formation of Microspore Tetrad**: After the first meiotic division, the microspore mother cell divides to form two microspores (dyad). Following this, a second meiotic division occurs, leading to the formation of a tetrad of four microspores.

3. **Protective Layer Formation**: The four microspores in the tetrad are surrounded by a protective layer. This layer is crucial for their development and protection during the early stages of microspore formation.

4. **Identifying the Protective Layer**: The protective layer that covers the tetrad of microspores is specifically known as **callose**. Callose is a polysaccharide that provides structural support and protection to the developing microspores.

5. **Function of Callose**: Callose not only protects the microspores from environmental factors but also aids in the differentiation process of the microspores as they develop into pollen grains.

6. **Eliminating Incorrect Options**:
- **Pectocellulose and Cellulose**: These are not the layers that cover the microspore tetrad.
- **Sporopollenin**: This is found in the mature pollen grain, specifically in the outer layer (exine), and is not the protective layer around the microspore tetrad.

7. **Conclusion**: Based on the above analysis, the correct answer is that the protective layer covering the four microspores of the tetrad is **callose**.

**Final Answer**: Callose

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