The gestation stage in which the zygote undergoes mitotic division and increases the number of cells by geometric progression is called ___________ .

Options

A. Cleavage
B. Blastulation
C. Gastrulation
D. Organogenesis

Answer

**Step-by-Step Solution:**

1. **Understanding the Zygote Stage**: The zygote is the initial cell formed when a sperm fertilizes an egg. It is a single cell that will undergo several stages of development.

2. **Mitosis and Cell Division**: After fertilization, the zygote undergoes mitotic division. Mitosis is the process by which a single cell divides to produce two identical daughter cells. This process continues, leading to an increase in the number of cells.

3. **Geometric Progression of Cell Division**: The term "geometric progression" refers to the way the number of cells increases exponentially. For example, after the first mitotic division, the zygote becomes two cells, then four cells after the second division, and eight cells after the third division, and so on.

4. **Identifying the Correct Term**: The specific stage of development where the zygote divides and increases in cell number through mitosis is known as "cleavage." This is the early stage of embryonic development.

5. **Conclusion**: Therefore, the gestation stage in which the zygote undergoes mitotic division and increases the number of cells by geometric progression is called **cleavage**.

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