Fusion of one male gamete with the egg cell and fusion of another male gamete with secondary nucleus is called

Options

A. Fertilisation
B. Double fertilisation
C. Triple fusion
D. Karyogamy

Answer

To answer the question regarding the fusion of one male gamete with the egg cell and the fusion of another male gamete with the secondary nucleus, we can break down the process as follows:

### Step-by-Step Solution:

1. **Understanding Gametes**: In flowering plants (angiosperms), male gametes are produced in the pollen grains. Each pollen grain contains two male gametes.

2. **Pollen Tube Formation**: When a pollen grain lands on the stigma of a flower, it germinates and forms a pollen tube that grows down into the ovule, where the embryo sac is located.

3. **Fertilization Events**: Inside the embryo sac, the two male gametes perform two distinct fusion events:
- **First Fusion**: One male gamete fuses with the egg cell (female gamete). This fusion results in the formation of a diploid zygote, which is referred to as syngamy.
- **Second Fusion**: The second male gamete fuses with the two polar nuclei present in the embryo sac. This fusion results in the formation of a triploid cell, which develops into the endosperm.

4. **Definition of Double Fertilization**: The process described above, where one male gamete fuses with the egg cell and the other fuses with the polar nuclei, is known as **double fertilization**. This is a unique characteristic of angiosperms.

5. **Conclusion**: Therefore, the correct answer to the question is **double fertilization**.

### Final Answer:
The fusion of one male gamete with the egg cell and the fusion of another male gamete with the secondary nucleus is called **double fertilization**.

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