The chromosomal ploidy status of zygote is (a) ........... and that of endosperm is (b)............

Answer

To answer the question regarding the chromosomal ploidy status of the zygote and endosperm, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Double Fertilization**:
- Double fertilization is a unique process that occurs in angiosperms (flowering plants). It involves the fusion of two male gametes with different female gametes.

2. **Formation of the Zygote**:
- During double fertilization, one male gamete fuses with the egg cell (female gamete) to form the zygote. This process is known as syngamy.

3. **Determining the Ploidy of the Zygote**:
- The zygote is formed by the fusion of one male gamete (haploid, n) and one egg cell (haploid, n). Therefore, the zygote has a total of two sets of chromosomes (n + n = 2n), making it diploid.
- **Answer for (a)**: The chromosomal ploidy status of the zygote is **diploid (2n)**.

4. **Formation of the Endosperm**:
- The second male gamete fuses with the two polar nuclei present in the central cell of the embryo sac. This fusion is known as triple fusion.

5. **Determining the Ploidy of the Endosperm**:
- The endosperm is formed by the fusion of one male gamete (haploid, n) with two polar nuclei (each haploid, n). Therefore, the endosperm has a total of three sets of chromosomes (n + n + n = 3n), making it triploid.
- **Answer for (b)**: The chromosomal ploidy status of the endosperm is **triploid (3n)**.

### Final Answers:
- (a) Zygote: **Diploid (2n)**
- (b) Endosperm: **Triploid (3n)**