In angiosperms, all the four microspores of a tetrad are covered by a layer formed by

Options

A. cellulose
B. sporopollenin
C. pectose
D. callose

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the layer that covers the four microspores of a tetrad in angiosperms. A tetrad consists of four microspores formed during meiosis in the pollen mother cell.

2. **Identifying the Options**: The options provided are:
- a) Cellulose
- b) Sporopollenin
- c) Pectose
- d) Callose

3. **Analyzing Each Option**:
- **Cellulose**: This is a polysaccharide that forms the primary cell wall of plants but is not specifically related to the covering of microspores.
- **Sporopollenin**: This is a tough, chemically inert polymer that forms the outer layer (exine) of pollen grains and spores, but it does not cover the tetrad of microspores directly.
- **Pectose**: This is an amorphous carbohydrate found mainly in unripe fruits and does not relate to the microspore covering.
- **Callose**: This is a polysaccharide that forms a layer around the microspores during their development, providing an isolation barrier between the microspores.

4. **Conclusion**: The correct answer is **Callose**. It surrounds the microspores during the meiotic stage and acts as a molecular filter, isolating the developing microspores from surrounding tissues.

**Final Answer**: The four microspores of a tetrad in angiosperms are covered by a layer formed by **Callose**.

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