What will be the ploidy of endosperm and zygote if the cross is made between a 6n female plant and a 4n male plant?

Options

A. 5n,8n
B. 8n,5n
C. 10n,7n
D. 6n,4n

Answer

To determine the ploidy of the endosperm and zygote when a cross is made between a 6n female plant and a 4n male plant, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Ploidy Levels**:
- The female plant has a ploidy level of 6n.
- The male plant has a ploidy level of 4n.

2. **Formation of Gametes**:
- The female gametes (egg cells) are produced from the female plant. Since the female plant is 6n, the gametes will have a ploidy of 6n/2 = 3n.
- The male gametes are produced from the male plant. Since the male plant is 4n, the gametes will have a ploidy of 4n/2 = 2n.

3. **Double Fertilization**:
- In plants, double fertilization occurs where one male gamete fuses with the egg cell to form the zygote, and the other male gamete fuses with the polar nuclei to form the endosperm.
- The zygote is formed by the fusion of the female gamete (3n) and one male gamete (2n).
- Therefore, the ploidy of the zygote = 3n + 2n = 5n.

4. **Endosperm Formation**:
- The endosperm is formed when the other male gamete (2n) fuses with the two polar nuclei (which together have a ploidy of 2n, since each polar nucleus is n).
- Therefore, the ploidy of the endosperm = 2n (from the male gamete) + 2n (from the two polar nuclei) = 4n.

5. **Final Ploidy Levels**:
- The ploidy of the zygote is 5n.
- The ploidy of the endosperm is 4n.

### Conclusion:
- The ploidy of the zygote is 5n, and the ploidy of the endosperm is 4n.