A human cell has 46 total or 23 pairs of chromosomes. Following mitosis, the daughter cells would each have a total of ______ chromosomes. After meiosis I, the two daughter cells would have _____chromosomes, and after meiosis II ______ chromosomes.
C. 46, 23, 23
-The chromosome number is reduced to one half during the first meiotic division. Recall that the number of chromosomes is determined by the number of centromeres, and not the number of chromatids
The process of meiosis produces four cells with nonidentical chromosomes. This diversification occurs during:
B. prophase 1
-Prophase I includes recombination of genetic material and the random arrangement of the homologous pairs, producing diversification of the resulting haploid cells
Which of the following is unique to mitosis and not a part of meiosis?
B. homologous chromosomes behave independently
-Pairing of homologous chromosomes allowing independent segregation and crossing over is unique to meiosis. In mitosis, homologous chromosomes behave independently.
The Thompson seedless grape is triploid, with three copies of each chromosome. Which phase of the cell cycle would you expect triploid cells to be unable to complete.
A. meiosis I
-True, homologous chromosomes must pair in meiosis I. Triploid cells would be unable to complete meiosis I.
Some organisms are capable of asexual or sexual reproduction. Under favorable conditions, reproduction proceeds asexually. When conditions become more stressful reproduction switches to a sexual mode. Why?
D. Sexual reproduction produces individuals with new combinations of recombined chromosomes increasing diversity.
-This answer provides the reason for sexual reproduction, and also interestingly enough, the reason for death. Our species survives if we increase variation by meiosis.
The stage of meiosis where cells become haploid.
B. anaphase I
-Separation of homologous pairs occurs at anaphase I. Even though each chromosome has two chromatids, the total number of chromosomes is 23 for humans after anaphase I of meiosis I. Recall that the number of chromosomes is determined by the number of centromeres.
One of the earliest events that distinguishes meiosis occurs in prophase I and involves:
A. Pairing of homologous chromosomes
-Pairing of chromosomes is unique to meiosis, and allows crossing over.
Coral in the ocean grows by budding, where the new organism grows out of the old one by mitosis. This form of replication is an example of:
C. asexual reproduction
-Yes, and can produce large numbers of organisms but without genetic diversity.
_________________ most closely resembles events of mitosis except that the cells are ___________.
A. meiosis II, haploid
-Yes, meiosis II events are similar to mitosis with haploid cells.
During anaphase, a free kinetochore formed by disrupting an attached spindle fiber results in an immediate block to the process. This result shows that:
A. The chromosomes themselves provide the energy for anaphase through their attachment to spindle fibers.
B. The cells have mechanisms to insure that errors are not made during anaphase.
B. The cells have mechanisms to insure that errors are not made during anaphase.
This observation is entirely correct. Scientists are now working on the mechanisms by which detachment is detected, a process probably involving phosphorylation.
