Question

Shaw University 8. 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. 9. 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 10. Use the figure above to answer the question. For an organism with a diploid number of 6, how are the chromosomes arranged during metaphase I of meiosis? RK KN a. A b. B с.С d. D

Answer 1

Ans 1) d) Karyokinesis occurs once in mitosis and twice in meiosis

In case of meiosis which is the production of the gametic cells, the nuclear division takes place twice and in mitosis it is only once. The process of crossing over which is the process of exchange of genetic material taking place between two homologous chromosome non sister chromatic takes place only in meiosis and not mitosis. The daughter cells produced during mitosis are genetically identical to each other but the meiosis daughter cells are not identical. The synapses which are the fusion of pair of chromosomes during the start of meiosis takes place in the prophase I of meiosis. Karyokinesis, the process of nucleus division takes place once in mitosis and twice in meiosis as there are two rounds of division of meiotic cells.

Ans 2) 19 minutes

The duration of the cell cycle here is 16 hours and hence converting it in minutes would be

16 hours x 60 minuters/hr = 960 minutes

There are 13 cells present in the anaphase which is to be divided by total cells of 600

= 13 cells in anaphase/660 total cell = 2% of cells present in anaphase

Now, 2% of 960 is 19 minutes which is the approximate duration of anaphase present in the cells.

Ans 3) C is the correct answer. In meiosis there are two round of divisions where in the first round there is separation of the homologous pairs. During this the tetrad tend to line up on metaphase plate within the metaphase I