Sporoderm’ refers to the :

Options

A. Exine and intine layers collectively
B. Wall of a sporangium
C. Wall of the spore mother cell
D. Callose deposition outside the PMC

Answer

**Step-by-Step Solution:**

1. **Understanding the Term "Sporoderm":**
- Sporoderm is a botanical term that refers to the outer layers of pollen grains. It is essential to know what constitutes the sporoderm.

2. **Identifying the Components of Sporoderm:**
- The sporoderm is composed of two main layers: the exine and the intine.
- **Exine:** This is the outer layer of the sporoderm. It is known for its hardness and is made of a resistant organic material called sporopollenin. The exine also contains germ pores, which are areas that lack sporopollenin.
- **Intine:** This is the inner layer of the sporoderm, located beneath the exine. It is primarily made up of cellulose, hemicellulose, and callose.

3. **Evaluating the Options Given:**
- The options provided in the question include:
- Exine and intine layers collectively
- Walls of the sporangium
- Wall of the spore mother cell
- Callose deposition outside the PMC (Pollen Mother Cell)
- Among these options, the first one, which refers to the exine and intine layers collectively, is the correct definition of sporoderm.

4. **Eliminating Incorrect Options:**
- The walls of the sporangium and the wall of the spore mother cell are not correct definitions of sporoderm as they refer to different structures in plant reproduction.
- Callose deposition is related to wound healing and is not a definition of sporoderm.

5. **Conclusion:**
- Therefore, the correct answer to the question "Sporoderm refers to the:" is the exine and intine layers collectively.

**Final Answer:**
Sporoderm refers to the exine and intine layers collectively.

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