Final answer:
A biologist may examine 200 cells to gain reliable data on cell cycle stages, with larger sample sizes providing more accurate results on the length of time cells spend in interphase and stages of mitosis.
Step-by-step explanation:
In biology, particularly when studying cell division and the cell cycle, it is important for scientists to examine a significant number of cells to obtain reliable data. The student's question is related to understanding the length of time cells spend in each stage of the cycle, based on observing cells in interphase and in various stages of mitosis. By examining a large number of cells, in this case, 200 cells, a biologist can more accurately estimate the length of time cells spend in each stage, since not all cells are synchronized in their division.
Interphase is the longest phase of the cell cycle and consists of three stages: G1, S, and G2. During this time, the cell grows, duplicates its DNA, and prepares for division. In contrast, the stages of mitosis are usually shorter and involve the separation of the cell's genetic material into two identical sets, followed by cell division.
The reason a biologist might choose to examine 200 cells instead of a smaller number, like the suggested 100 cells, is to improve the reliability of the data (Option a). A larger sample size helps smooth out anomalies and provides a more accurate snapshot of cell population dynamics. Thus, examining 200 cells is not just standard practice (Option b) but a methodological choice to enhance the quality of the results. Other options such as the ease of counting (Option c) or having spare time (Option d) are less scientific reasons for the choice.