Which of the following is not a part of a typical embryo sac formation in angiosperms ?

Options

A. The MMC undergoes meiotic division to form 4 megaspores.
B. Three mitotic divisions occur in a megaspore to form an eight nucleate stage.
C. The cell walls are formed with 3 cells grouped together at chalazal end, together called the egg apparatus.
D. The egg apparatus contains two synergids and one egg cell .

Answer

To solve the question "Which of the following is not a part of a typical embryo sac formation in angiosperms?", we will follow these steps:

### Step 1: Understand the Embryo Sac Formation
The embryo sac in angiosperms is the female gametophyte that develops within the ovule. It typically involves the following processes:
- The megaspore mother cell undergoes meiosis to produce four megaspores, of which usually one survives.
- This surviving megaspore undergoes three rounds of mitotic division.

### Step 2: Identify the Structure of the Embryo Sac
The typical structure of the embryo sac consists of:
- **Three antipodal cells** at the chalazal end.
- **One egg cell and two synergids** at the micropylar end, forming the egg apparatus.
- **One central cell** that contains two polar nuclei.

### Step 3: Analyze the Options
Now, we need to analyze the options provided in the question to identify which one does not belong to the typical embryo sac formation.

### Step 4: Determine the Incorrect Option
From the explanation in the video transcript:
- The antipodal cells are indeed located at the chalazal end.
- The egg apparatus (egg cell and synergids) is located at the micropylar end.
- The central cell is located in the center of the embryo sac.

The option that states "the three cells are formed in the three cell group together at the chalazal end" is incorrect because the egg apparatus is located at the micropylar end, not the chalazal end.

### Conclusion
Thus, the correct answer to the question is the option that states the incorrect formation related to the embryo sac.

**Final Answer: The option stating "the three cells are formed in the three cell group together at the chalazal end" is not a part of a typical embryo sac formation in angiosperms.**

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