Double fertilization is

Options

A. Syngamy and triple fusion
B. Fusion of two male gametes with one egg
C. Fusion of one male gamete with two polar nuclei
D. Fusion of two male gametes of a pollen tube with two different eggs.

Answer

**Step-by-Step Solution:**

1. **Understanding Double Fertilization**: Double fertilization is a unique process that occurs in flowering plants (angiosperms). It involves two distinct fertilization events that happen simultaneously.

2. **Structure of the Embryo Sac**: The embryo sac contains several types of cells:
- **Antipodal Cells**: Three cells located at the opposite end of the micropyle.
- **Synergids**: Two cells located near the micropyle that assist in guiding the pollen tube.
- **Egg Cell**: The female gamete located near the synergids.
- **Central Cell**: Contains two polar nuclei and is located in the center of the embryo sac.

3. **Pollen Tube Growth**: When the pollen grain germinates, it forms a pollen tube that grows towards the embryo sac. The pollen tube enters through one of the synergid cells.

4. **Release of Male Gametes**: The pollen tube releases two male gametes into the embryo sac.

5. **First Fertilization Event (Syngamy)**:
- One male gamete fuses with the egg cell to form the zygote.
- This process is called syngamy, and the zygote is diploid (2n) because it is formed by the fusion of two haploid (n) gametes (one male and one female).

6. **Second Fertilization Event (Triple Fusion)**:
- The second male gamete fuses with the two polar nuclei in the central cell.
- This fusion results in the formation of the endosperm, which is triploid (3n) because it involves the fusion of one male gamete (n) with two polar nuclei (each n).

7. **Conclusion**: The entire process of one male gamete fusing with the egg cell and the other male gamete fusing with the central cell is termed double fertilization. This process is characteristic of angiosperms and is essential for the development of both the embryo and the endosperm.

**Final Answer**: Double fertilization involves syngamy (fusion of one male gamete with the egg cell) and triple fusion (fusion of the second male gamete with the two polar nuclei).

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