1. Which of the following statements is correct? a.
Crossing over occurs in prophase I of meiosis and metaphase of mitosis. b.
DNA replication occurs once prior to mitosis and twice prior to meiosis. c.
Both mitosis and meiosis result in daughter cells identical to the parent cells. d.
Karyokinesis occurs once in mitosis and twice in meiosis. e.
Synapsis occurs in prophase of mitosis.
The correct answer is d: There are two nuclear divisions in meiosis, and only one in mitosis. Crossing over occurs only in meiosis; it does not occur at all in mitosis. Replication occurs only once in preparation for both mitosis and meiosis. The daughter cells of mitosis are identical to the parent cell, but in meiosis the daughter cells have only one of each homologous chromosome pair. Synapsis occurs only in prophase I of meiosis.
2. The cell cycle in a certain cell type has a duration of 16 hours. The nuclei of 660 cells showed 13 cells in anaphase. What is the approximate duration of anaphase in these cells? a.
2 minutes b.
13 minutes c.
19 minutes d.
32 minutes e.
647 minutes
The correct response is c. Correct calculation:
16 hours x 60 minutes/hour = 960 minutes.
13 cells in anaphase

660 total cells =
2% of the cells in anaphase
2% of 960 is approximately 19 minutes.
Use the following figure to answer questions 3 and 4.
3. For an organism with a diploid number of 6, how are the chromosomes arranged during metaphase I of meiosis? a.
A b.
B c.
C d.
D
Correct response is c. Remember that there are two divisions in

5. How many of these asci are the result of crossing over? a.
3 b.
7 c.
8 d.
10 e.
15
Correct response is d. Remember that if crossing over does not occur, the arrangement of spores will be 4 light and 4 dark. All other combinations are the result of crossing over.
6. From this small sample, calculate the map distance between the gene and centromere. a.
10 map units b.
20 map units c.
30 map units d.
40 map units
The correct response is b. If you got a different answer, check your calculations. Did you remember to divide the number of crossovers (10) by 2?