Which of the following is not a characteristic of cleavage ?

Options

A. they may be asynchronous
B. they may result in the formation of unequal cells
C. they bring about appreciable growth
D. they are slow divisions

Answer

### Step-by-Step Solution:

1. **Understanding Cleavage**: Cleavage refers to the series of rapid cell divisions that occur after fertilization. It is characterized by the division of a single fertilized egg (zygote) into multiple smaller cells called blastomeres.

2. **Characteristics of Cleavage**:
- **Asynchronous Division**: Cleavage can be asynchronous, meaning that the timing of cell divisions may not be uniform. Initially, the cells divide at different times for about 12 to 14 hours after fertilization.
- **Formation of Unequal Cells**: In certain types of eggs, like megalecithal eggs (found in birds), cleavage can lead to the formation of unequal-sized cells due to the presence of a large yolk.
- **Growth During Cleavage**: Cleavage does not result in appreciable growth of the embryo. The overall size does not increase significantly during this phase; rather, the zygote is simply dividing into smaller cells.
- **Slow Division**: Cleavage is generally a rapid process, but the overall division can be considered slow in terms of the entire developmental timeline.

3. **Identifying the Incorrect Characteristic**: Among the options provided, the statement that cleavage brings about appreciable growth is incorrect. Cleavage primarily focuses on dividing the zygote into smaller cells without significant growth in size.

4. **Conclusion**: The characteristic that is NOT associated with cleavage is that it brings about appreciable growth.

### Final Answer:
The characteristic that is not associated with cleavage is: **They bring about appreciable growth.**

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