A dioecious species possess XY genotype for male and XX for female. After double fertilization, what would be the genotypes of the embryo and endosperm respectively?

Options

A. X and XX (or) Y and XY
B. XX and XX (or) XY and XY
C. XX and YYY (or) XY and XXY
D. XX and XXY (or) XY and XXX

Answer

To solve the question regarding the genotypes of the embryo and endosperm after double fertilization in a dioecious species with XY genotype for males and XX for females, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Dioecious Species**:
- Dioecious species have distinct male and female plants. In this case, the male has the genotype XY and the female has the genotype XX.

2. **Double Fertilization Process**:
- In flowering plants, double fertilization occurs when one male gamete fuses with the egg cell (female gamete) to form the embryo, and the other male gamete fuses with the two polar nuclei to form the endosperm.

3. **Gamete Contribution**:
- The female gamete (egg cell) from the female plant will always contribute an X chromosome (since the female genotype is XX).
- The male gamete can contribute either an X or a Y chromosome (since the male genotype is XY).

4. **Formation of the Embryo**:
- If the male gamete that fuses with the female egg is X, the resulting embryo will have the genotype XX (X from the female and X from the male).
- If the male gamete that fuses with the female egg is Y, the resulting embryo will have the genotype XY (X from the female and Y from the male).

5. **Formation of the Endosperm**:
- The endosperm is formed by the fusion of the second male gamete with the two polar nuclei (which are both X, since they come from the female plant).
- Therefore, regardless of whether the first male gamete was X or Y, the endosperm will always have the genotype XXY (X from one polar nucleus, X from the other polar nucleus, and Y from the second male gamete).

6. **Conclusion**:
- The possible genotypes for the embryo are either XX or XY, and the genotype for the endosperm will be XXY.

### Final Answer:
- **Embryo Genotype**: XX or XY
- **Endosperm Genotype**: XXY