In double fertilization, male gamete and secondary nucleus form

Options

A. Endosperm
B. Gamete
C. Embryo
D. Egg.

Answer

### Step-by-Step Solution

1. **Understanding Double Fertilization**:
- Double fertilization is a unique process that occurs in angiosperms (flowering plants). It involves two fertilization events within the ovule.

2. **Structure of the Ovule**:
- The ovule consists of several key components:
- **Antipodal Cells**: Located at the chalazal end, typically three in number.
- **Synergids**: Found at the micropilar end, usually two in number, which help guide the pollen tube.
- **Egg Cell**: Located between the synergids, which is the female gamete.
- **Central Nuclei (Polar Nuclei)**: Two nuclei located centrally within the ovule.

3. **Pollen Grain Arrival**:
- When pollen grains arrive at the ovule, one pollen grain will fertilize the egg cell, resulting in the formation of the zygote (the first fertilization event).

4. **Formation of the Primary Endosperm Nucleus**:
- The second pollen grain travels to the central nuclei (polar nuclei) and fuses with them. Since there are two polar nuclei (2n) and one pollen grain (n), the fusion results in a triploid nucleus (3n), known as the primary endosperm nucleus (PEN).

5. **End Result**:
- The two fertilization events lead to the formation of:
- A diploid zygote from the fusion of the male gamete and the egg cell.
- A triploid primary endosperm nucleus that will develop into the endosperm, providing nourishment to the developing embryo.

### Final Answer
In double fertilization, the male gamete fuses with the egg cell to form a zygote, while another male gamete fuses with the two polar nuclei to form the primary endosperm nucleus (PEN), which will develop into the endosperm.

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