What is the ploidy of primary endosperm nucleus (PEN) in angiosperm ?

Options

A. Haploid
B. Diploid
C. Triploid
D. Tetraploid

Answer

**Step-by-Step Solution:**

1. **Understanding Double Fertilization**: In angiosperms (flowering plants), a unique process called double fertilization occurs. This involves two male gametes entering the embryo sac via the pollen tube.

2. **Formation of Zygote**: One of the male gametes fuses with the female gamete (egg cell) to form the zygote. The zygote is a diploid structure (2n) because it is formed by the fusion of one haploid male gamete (n) and one haploid female gamete (n).

3. **Formation of Primary Endosperm Nucleus (PEN)**: The second male gamete fuses with the secondary nucleus, which is formed by the fusion of two polar nuclei. Since the secondary nucleus is diploid (2n), the fusion with the haploid male gamete (n) results in the formation of the primary endosperm nucleus (PEN).

4. **Determining the Ploidy of PEN**: The fusion of the diploid secondary nucleus (2n) and the haploid male gamete (n) results in a triploid structure (3n). Therefore, the primary endosperm nucleus (PEN) is triploid.

5. **Conclusion**: Thus, the ploidy of the primary endosperm nucleus (PEN) in angiosperms is triploid (3n).

**Final Answer**: The ploidy of the primary endosperm nucleus (PEN) in angiosperms is triploid (3n).

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