In animal cells, cytokinesis occurs by cleavage method. Here the cell membrane grows ____ to divide a cell into two.

Options

A. centripetally
B. centrifugally
C. asymmetrically
D. gravitationally

Answer

To answer the question regarding how cytokinesis occurs in animal cells by the cleavage method, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding Cytokinesis**: Cytokinesis is the process that follows mitosis, where the cytoplasm of a parental cell divides to form two daughter cells. In animal cells, this process occurs through a mechanism known as cleavage.

2. **Formation of Cleavage Furrow**: During cytokinesis in animal cells, the cell membrane begins to constrict. This constriction is facilitated by the action of microfilaments, which are part of the cytoskeleton. These microfilaments form a structure called the cleavage furrow.

3. **Direction of Cleavage Furrow Formation**: The cleavage furrow starts at the periphery (outer edge) of the cell and moves inward toward the center. This inward movement is described as "centripetal" because the furrow is moving towards the center of the cell.

4. **Deepening of the Furrow**: As the cleavage furrow deepens, it continues to extend inward until the two sides of the cell membrane meet at the center.

5. **Completion of Cytokinesis**: When the furrow reaches the center and the two membranes meet, the cell is pinched off, resulting in two separate daughter cells. This process effectively divides the original cell into two distinct cells.

### Final Answer:
In animal cells, cytokinesis occurs by the cleavage method, where the cell membrane grows **centripetally** to divide a cell into two.

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