Question

refer to the table. a student ran the simulation using one pair of homologous chromosomes in the parent cell. she elected to have crossing over occur during the simulation. this table summarizes some of the information resulting from the simulation.

	mitosis	meiosis
number of different cells created	1	40
number of unique cells created	0	40

how many cell cycles must have occurred to account for these results, and how would the meiosis results have differed if crossing over had not occurred? use the simulation to test your predictions.
o 5 cell cycles; fewer unique cells only
o 5 cell cycles; fewer different cells and fewer unique cells
o 10 cell cycles; fewer unique cells only
o 10 cell cycles; fewer different cells and fewer unique cells

Explanation:

Step1: Recall cell - division facts

In mitosis, one cell cycle produces 2 daughter cells that are genetically identical to the parent cell. In meiosis, one cell cycle produces 4 daughter cells that are genetically different from the parent cell and from each other (especially when crossing - over occurs).

Step2: Calculate mitosis cell cycles

If in mitosis, the total number of cells created is 20. Since one mitosis cell cycle produces 2 cells, the number of mitosis cell cycles is $\frac{20}{2}=10$. But this is not relevant to the main question about meiosis.

Step3: Calculate meiosis cell cycles

If in meiosis, the total number of cells created is 40. Since one meiosis cell cycle produces 4 cells, the number of meiosis cell cycles is $\frac{40}{4}=10$.

Step4: Analyze effect of crossing - over

Crossing - over during meiosis increases genetic variation. If crossing - over had not occurred, there would be fewer different and fewer unique cells produced during meiosis.

Answer:

10 cell cycles; fewer different cells and fewer unique cells