During cleavage , what is true about embryo ?

Options

A. Nucleocytoplasmic ratio remains unchanged
B. Sizes does not increase
C. There is less consumption of oxygen
D. The division is like meiosis.

Answer

**Step-by-Step Solution:**

1. **Understanding Cleavage**: Cleavage is the process that occurs after fertilization, where the zygote undergoes repeated mitotic divisions. This results in an increasing number of cells, leading to the formation of a structure called the blastula.

2. **Analyzing the Options**:
- **Option 1: Nucleocytoplasmic ratio remains unchanged**: During cleavage, the nucleocytoplasmic ratio (the ratio of the nucleus to the cytoplasm) actually increases as the number of cells increases. Therefore, this statement is incorrect.

- **Option 2: Sizes does not increase**: During cleavage, the overall size of the embryo does not increase because the divisions are occurring without growth. This statement is correct.

- **Option 3: There is less consumption of oxygen**: Oxygen consumption actually increases during cleavage, especially as it approaches the blastocyst stage, where it can increase by 60 to 70%. Thus, this statement is incorrect.

- **Option 4: The division is like meiosis**: Cleavage involves mitotic divisions, not meiotic divisions. Therefore, this statement is also incorrect.

3. **Conclusion**: The only true statement about the embryo during cleavage is that the size does not increase.

**Final Answer**: The correct statement about the embryo during cleavage is that the size does not increase.

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