An angiospermic male plant with 24 chromosomes in its pollen mother cells is crossed with female plant bearing 24 chromosomes in its root cells . What would be the ploidy of embryo and endosperm respectively formed after this cross ?

Options

A. 24 and 48
B. 24 and 24
C. 48 and 72
D. 24 and 36

Answer

To solve the problem, we need to determine the ploidy levels of the embryo and endosperm formed after the cross between the male and female angiospermic plants.

### Step-by-step Solution:

1. **Identify the Ploidy of Male and Female Plants:**
- The male plant has 24 chromosomes in its pollen mother cells. Since pollen mother cells are diploid (2n), the male plant's ploidy is 2n = 24.
- The female plant also has 24 chromosomes in its root cells, which are also diploid (2n). Therefore, the female plant's ploidy is also 2n = 24.

2. **Determine the Ploidy of Gametes:**
- During meiosis, the diploid pollen mother cells (2n) produce haploid pollen grains (n). Since the male plant has 24 chromosomes, each pollen grain will have n = 12 chromosomes.
- Similarly, the female plant produces haploid ovules (n) from its diploid ovule mother cells. Therefore, the ovules will also have n = 12 chromosomes.

3. **Fertilization Process:**
- When the male gamete (pollen grain) fertilizes the female gamete (ovule), the resulting zygote (which develops into the embryo) will be diploid.
- The ploidy of the embryo is calculated as follows:
- Ploidy of embryo = n (from male) + n (from female) = 12 + 12 = 2n = 24.

4. **Formation of Endosperm:**
- In angiosperms, the endosperm is formed from the fusion of one male gamete with two polar nuclei in the embryo sac. This results in a triploid (3n) endosperm.
- The ploidy of the endosperm can be calculated as follows:
- Ploidy of endosperm = n (from male) + 2n (from two polar nuclei) = 12 + 24 = 36.

5. **Final Answer:**
- Therefore, the ploidy of the embryo is 24 and the ploidy of the endosperm is 36.

### Conclusion:
The correct answer is option D: 24 (embryo) and 36 (endosperm).