How does endosperm in angiosperm become triploid?

Explanation

**Step-by-Step Solution:**

1. **Understanding the Structure of Angiosperms**: Angiosperms, or flowering plants, undergo a unique reproductive process that involves the formation of seeds and fruits. A key component of this process is the endosperm, which serves as a nutrient source for the developing embryo.

2. **The Process of Double Fertilization**: In angiosperms, a process known as double fertilization occurs. This involves the fusion of one male gamete (sperm) with the egg cell to form the zygote, while the other male gamete fuses with two polar nuclei located in the central cell of the ovule.

3. **Formation of the Endosperm**: The fusion of the second male gamete with the two polar nuclei results in the formation of a triploid nucleus. This nucleus is referred to as the endosperm nucleus. Since the male gamete contributes one set of chromosomes (haploid) and the two polar nuclei contribute two sets (diploid), the resulting endosperm is triploid (3n).

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