Question

Give reasons why endosperm in angiosperms becomes triploid.

Answer 1

1. In angiosperms, one male gamete fuses with the egg to form a diploid zygote.
2. The other male gamete fuses with two polar nuclei of the embryo sac.
3. Since two polar nuclei are haploid, their fusion with one male gamete forms a triploid primary endosperm nucleus.
4. This triploid nucleus develops into the endosperm, which nourishes the developing embryo.

Thus, endosperm is triploid due to the fusion of one male gamete with two polar haploid nuclei (triple fusion).