When the pollen tube enters the embryo sac, which of the following cell usually gets burst on its entry:

Options

A. Both synergids
B. Central cell
C. Antipodals
D. One of the two synergids

Answer

To solve the question, "When the pollen tube enters the embryo sac, which of the following cell usually gets burst on its entry?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Structure of the Embryo Sac**:
The embryo sac in flowering plants typically consists of seven cells: one egg cell, two synergids, and three antipodal cells. The synergids are located at the micropyle end of the embryo sac.

**Hint**: Remember the components of the embryo sac and their locations.

2. **Role of the Pollen Tube**:
The pollen tube is responsible for delivering sperm cells to the egg cell for fertilization. It grows through the style and enters the embryo sac.

**Hint**: Think about the function of the pollen tube in fertilization.

3. **Entry Point of the Pollen Tube**:
The pollen tube usually enters the embryo sac through one of the synergids. The synergids have specialized structures called filiform apparatus that help guide the pollen tube.

**Hint**: Focus on where the pollen tube penetrates the embryo sac.

4. **Effect of Pollen Tube Entry**:
Upon entry, the pollen tube causes one of the synergids to burst. This is because the pollen tube penetrates the synergid to release the sperm cells, leading to the disintegration of the synergid.

**Hint**: Consider what happens to the cells when the pollen tube enters.

5. **Conclusion**:
Therefore, the correct answer to the question is that one of the two synergids usually gets burst upon the entry of the pollen tube into the embryo sac.

**Final Answer**: One of the two synergids.