The number of cells in the Polygonum type of embryo sac which degenerate after fertilization

Options

A. 2
B. 7
C. 5
D. 8

Answer

To determine the number of cells in the Polygonum type of embryo sac that degenerate after fertilization, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of the Polygonum Type Embryo Sac**:
- The Polygonum type of embryo sac is the most common type found in angiospermic plants.
- It consists of **7 cells** and **8 nuclei**.

2. **Identify the Cells Present in the Embryo Sac**:
- There are three antipodal cells located at the chalazal end.
- One central cell is located in the center.
- The egg apparatus, located at the micropylar end, consists of:
- Two synergid cells
- One egg cell

Therefore, the breakdown of the cells is as follows:
- Antipodal cells: 3
- Central cell: 1
- Synergid cells: 2
- Egg cell: 1

3. **Total Cells in the Embryo Sac**:
- The total number of cells = 3 (antipodal) + 1 (central) + 2 (synergids) + 1 (egg) = **7 cells**.

4. **Identify Which Cells Degenerate After Fertilization**:
- During fertilization, only the central cell and the egg cell participate in the process (double fertilization).
- The antipodal cells and synergid cells do not participate in fertilization and will degenerate.

5. **Count the Degenerating Cells**:
- Antipodal cells: 3 (degenerate)
- Synergid cells: 2 (degenerate)
- Total degenerating cells = 3 (antipodal) + 2 (synergids) = **5 cells**.

6. **Conclusion**:
- The number of cells in the Polygonum type of embryo sac that degenerate after fertilization is **5**.

### Final Answer:
The number of cells in the Polygonum type of embryo sac that degenerate after fertilization is **5**.

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