Which one is Triploid?

Question

Accepted Answer

The correct option is 3:

Endosperm is a unique tissue found in the seeds of flowering plants (angiosperms) that serves as a vital nutritive tissue for the developing embryo. Its triploid (3n) nature arises from a process called double fertilization, which is a hallmark of angiosperm reproduction. During double fertilization, one sperm nucleus fuses with the egg cell to form a diploid zygote (2n), which develops into the embryo. Simultaneously, the other sperm nucleus fuses with two polar nuclei, which are typically haploid (n) but merge to form a diploid (2n) central cell nucleus. The fusion of this diploid central cell nucleus with a haploid sperm nucleus results in a triploid (3n) primary endosperm nucleus, which then develops into the endosperm. This triploid genetic composition ensures that the endosperm has sufficient genetic material to synthesize and store the necessary nutrients, such as carbohydrates, proteins, and lipids, that are crucial for the embryo's growth and eventual germination. Therefore, the endosperm is distinctively triploid, providing a rich energy source for the nascent plant.

The incorrect option is 1: Megaspore

A megaspore is a haploid (n) spore produced during megasporogenesis in flowering plants. It is formed through meiosis from a diploid megaspore mother cell (megasporocyte). Typically, only one of the four megaspores produced becomes functional and develops into the female gametophyte (embryo sac), which contains the egg cell.

The incorrect option is 2: Embryo

The embryo in flowering plants is diploid (2n). It develops from the zygote, which is formed by the fusion of a haploid sperm nucleus and a haploid egg cell. The embryo is the rudimentary plant within the seed, containing the embryonic axis and cotyledons, and is responsible for developing into a new plant upon germination.

The incorrect option is 4: Microspore

A microspore is a haploid (n) spore produced during microsporogenesis in flowering plants. It is formed through meiosis from a diploid microspore mother cell (microsporocyte) within the anther. Each microspore then develops into a pollen grain, which contains the male gametes.