Read the passage carefully and answer the questions based on the passage:

Passage: Pollen pistil interaction involves all events from the landing of pollen grains on the stigma until the pollen tube enters the embryo sac (when the pollen is compatible). When a pollen tube grows through the style and enters into the ovules, it finally discharges two male gametes in one of the synergids.

Syngamy and triple fusion are two fusion events that occur in angiosperms. Thus, angiosperms exhibit double fertilization. The products of these fusions are the diploid zygote and triploid primary endosperm nucleus. Zygote develops into embryo and primary endosperm cell forms the endosperm tissue. The developing embryo passes through different stages before maturation.

If there are 38 chromosomes in the zygote, how many chromosomes will there be in its haploid egg cell?

The correct option is 19.

Let us break down the explanation step-by-step:

1. Understanding Ploidy Levels:
In angiosperms (flowering plants), the zygote is a diploid structure. This means it contains two complete sets of chromosomes, represented as 2n.
An egg cell, on the other hand, is a female gamete, which is haploid. This means it contains only one set of chromosomes, represented as n.

2. Relating Zygote and Egg Cell Chromosomes:
Since the zygote is formed by the fusion of a haploid egg cell (n) and a haploid male gamete (n), its chromosome count is twice that of the egg cell.

Mathematically, we can write this relationship as:
$$\text{Chromosomes in zygote (2n)}=2\times \text{Chromosomes in egg cell (n)}$$

3. Calculating the Number of Chromosomes in the Egg Cell:
We are given that the zygote contains 38 chromosomes.
$$2n=38$$
To find the chromosome number in the haploid egg cell (n), we divide the zygote's chromosome number by 2:
$$n=\frac{38}{2}=19$$
Therefore, there will be 19 chromosomes in the haploid egg cell.