If the male plant is tetraploid and female plant is diploid, what will be the ploidy level of endosperm after fertilization ?

Options

A. 3n
B. 4n
C. 5n
D. 6n

Answer

To determine the ploidy level of the endosperm after fertilization when the male plant is tetraploid (4n) and the female plant is diploid (2n), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Ploidy Levels**:
- The male plant is tetraploid, which means it has a ploidy level of 4n.
- The female plant is diploid, which means it has a ploidy level of 2n.

2. **Understand Gamete Formation**:
- In plants, the male gametes are produced from the microspore mother cell through meiosis. Since the male plant is tetraploid (4n), the microspore mother cell will also be 4n.
- After meiosis, the microspore mother cell produces haploid pollen grains (male gametes), which will have a ploidy level of 2n/2 = n. Therefore, each pollen grain (male gamete) will be haploid (n).

3. **Female Gamete Formation**:
- The female gametes are produced from the megaspore mother cell, which is diploid (2n). After meiosis, the megaspore mother cell produces haploid female gametes, which will also have a ploidy level of n.

4. **Double Fertilization Process**:
- In flowering plants, double fertilization occurs. One male gamete (n) fuses with the egg cell (n) to form the zygote (2n), which will develop into the embryo.
- The second male gamete (n) fuses with the two polar nuclei (which are also n each) in the central cell of the female gametophyte. This fusion results in the formation of the primary endosperm nucleus.

5. **Calculate the Ploidy of the Endosperm**:
- The two polar nuclei contribute a total of n + n = 2n.
- The second male gamete contributes n.
- Therefore, the ploidy level of the endosperm after fertilization will be 2n (from the polar nuclei) + n (from the male gamete) = 3n.

6. **Final Answer**:
- The ploidy level of the endosperm after fertilization will be **3n**.

### Answer:
The ploidy level of the endosperm after fertilization is **3n**.