What is the correct sequence in the formatio of female gametophyte in angiosperms?

Options

A. (a) Nuclellus`to`Megaspore tetrad `to` Megaspore mother cells `to` Megaspore female gametophyte
B. (b) Megaspore tetrad `to` nucellus `to` megaspore mother cells `to` megaspore `to` female gametophyte
C. (c) Nucellus `to`Megaspore mother cell `to` megaspore tetrad`to`megaspore`to` female gametophyte.
D. (d) Megaspore mother cell`to`megaspore tetrad `to` megaspore `to` nucellus `to` female gametophyte.

Answer

To determine the correct sequence in the formation of the female gametophyte (embryo sac) in angiosperms, we can break down the process into the following steps:

### Step-by-Step Solution:

1. **Megaspore Mother Cell (MMC)**: The process begins with the megaspore mother cell, also known as the MMC. This cell is diploid and is located within the ovule of the ovary.

2. **Meiosis**: The megaspore mother cell undergoes meiosis, a type of cell division that reduces the chromosome number by half. This results in the formation of four haploid megaspores.

3. **Megaspore Tetrad**: After meiosis, the four megaspores are arranged in a group known as a megaspore tetrad.

4. **Degeneration of Megaspores**: Out of the four megaspores formed, three typically degenerate and only one remains viable. This surviving megaspore will develop into the female gametophyte.

5. **Formation of Embryo Sac**: The remaining megaspore undergoes mitotic divisions, leading to the formation of the embryo sac, which is the female gametophyte. This process requires nutrition, which is provided by the surrounding nucellus tissue.

6. **Nucellar Support**: The nucellus, which is the tissue surrounding the megaspore, provides the necessary nutrients for the development of the embryo sac.

### Correct Sequence:
1. Megaspore Mother Cell (MMC)
2. Meiosis
3. Megaspore Tetrad
4. Degeneration of three megaspores
5. Formation of the Embryo Sac (female gametophyte)
6. Nutritional support from the Nucellus

### Final Answer:
The correct sequence in the formation of the female gametophyte in angiosperms is:
1. Megaspore Mother Cell (MMC)
2. Meiosis
3. Megaspore Tetrad
4. Degeneration of three megaspores
5. Formation of the Embryo Sac
6. Nutritional support from the Nucellus

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