Question

After mitosis, the chromosome number of a daughter cell is….that of parent cells.
A. Doubled compared to
B. One- half
C. The same as
D. Rearranged compared to

Answer 1

Hint: S phase is the replication phase where DNA replication occurs. Following the S phase, occurs the G2 phase where protein machinery for mitosis is prepared. In the mitosis phase, the cell divides.

Step by step answer:Option A) After mitosis, the chromosome number of a daughter cell is doubled compared to that of parent cells. The parent cell has 23pairs of chromosomes (one set from mother and one set from father) i.e., 46 chromosomes. During the S phase, the replication of the DNA occurs and the cell forms complementary DNA to the parent DNA template and a copy of the parent chromosomes is prepared and forms sister chromatids attached to the centromere. The prophase and metaphase of mitosis have 92 chromatids. At anaphase each chromatid is considered a single chromosome thus at the end of telophase, 92 chromosomes are present (double of 46 chromosomes of parent cell). After cytokinesis and karyokinesis, the cell divides into two each daughter cell having the 46 chromosomes forming a total of 92 chromosomes in two cells divided.
-Option B) After mitosis, the chromosome number of a daughter cell cannot be one- half that of parent cells because the S phase or the replication phase occurs before the beginning of mitosis.
-Option C) After mitosis, the chromosome number of a daughter cell cannot be the same as that of parent cells because the S phase or the replication phase occurs before the beginning of mitosis. If the S phase is not completed properly or there is some hindrance in the replication, the cell cycle checkpoints do not allow the progress of the cell cycle and it will not enter the mitosis phase.
-Option D) During the metaphase, the sister chromatids are pulled towards the pole by spindle fibers. But after telophase, cytokinesis, and karyokinesis, the cell will divide, and will each cell will have 46 chromosomes which are the replicated copies of the parent cell. Recombination between the sister chromatids occurs in meiosis and not in mitosis so no rearrangement occurs.
Hence, the correct option is (A).

Note: A human has 46 chromosomes or 23 pairs, each set inherited from mother and father. The S phase of the cell cycle is responsible for the duplication of genetic material which can then be divided equally after the cell divides.