1.
At the start of mitosis a chromosome is made up of two:
Correct Answer
C. Chromatids
Explanation
Centromere: Holds the two sister chromatids together.
Centriole: Organelle in plant cells. Spindle fiber attaches to these for cell division.
Chromatids: Two identical duplicated chromosomes.
2.
Which of the following is NOT an advantage of asexual reproduction?
Correct Answer
A. Increases genetic diversity
Explanation
Asexual reproduction will produce the organisms with the SAME genetic code -- no diversity!
3.
A scientist performs an experiment to determine the effect of temperature on the developmental time of flies. (Larva to adult fly)Which of the following would most likely be true?
Correct Answer
B. The rate of cell division is faster at the increased temperature.
Explanation
This is an inverse relationship. As the temperature goes up, the number of hours goes down.
While the number of hours decreases at higher temperature, there is no way of knowing if it will be half the hours at twice the temperature (18 to 36 C). At some point, the increased temperature will most likely kill the larva by denaturing (unraveling) enzymes.
4.
Which of the following occurs during the S phase of the cell cycle?
Correct Answer
A. The genetic material is duplicated.
Explanation
Cell growth occurs mainly during G1 and G2.
S phase (Between G1 and G2) is for SYNTHESIS of genetic material -- the chromatin is duplicated.
Organelles will increase during G2.
5.
Emmet noticed that his tarantula had molted (it shed off its outer skin) and now was larger in size than when he first received his pet. Which explanation BEST describes what happened?
Correct Answer
C. The total number of cells in the tarantula increased.
Explanation
As the tarantula molted and became larger, the best explanation is that the total number of cells in the tarantula increased. This is because during molting, the tarantula sheds off its outer skin, revealing a new, larger exoskeleton underneath. In order for the tarantula to grow in size, it needs to produce more cells to fill in the larger exoskeleton. Therefore, the increase in size is a result of an increase in the total number of cells in the tarantula.
6.
A dog will have 78 chromosomes in its nucleus. During the S phase of the cell cycle_____ number of chromatids will be in the nucleus and after mitosis (and cytokinesis) _____ number will be present in the nucleus.
Correct Answer
A. 156; 78
Explanation
During the S phase, the genome will double; At the end of cytokinesis - each daughter cell will be back to the original number of chromosomes -- 78.
7.
Look at the data table below showing the diploid number of chromosomes in various organism. Which of the following is the best explanation for why each of these organisms have a even number of chromosomes?
Correct Answer
C. The diploid number represents a pair of chromosomes -- one from each parent -- so it will always be an even number.
Explanation
For example: Humans receive 23 chromosomes from each parent; So 2n (diploid) is 46 chromosomes.
The diploid number (the total genome) will always be an even number.
8.
Which phase of the cell cycle are chromosomes first visible?
Correct Answer
B. PropHase
Explanation
Chromosomes are NOT visible during interphase.
9.
Which phase of the cell cycle is characterized by the chromosomes all gathering in a plane across the middle of the cell?
Correct Answer
C. MetapHase
Explanation
Chromosomes MEET in the Middle during METaphase
10.
Which phase of the cell cycle completes the division of a cell?
Correct Answer
F. Cytokinesis
Explanation
Cell division is complete after cytokinesis - two daughter cells will be present. Each daughter cell will have the same number of chromosomes as its parent. For example in humans, each body cell has 46 chromosomes. After mitosis, each daughter cell will have 46 chromosomes.
11.
Which phase of the cell cycle does the nuclear membrane breaks down?
Correct Answer
B. PropHase
Explanation
During prophase: The chromatin condenses and can now be seen with a light microscope. The sister chromatids are visible and are joined at the centromere. The nucleolus disappears and the nuclear membrane (aka envelope) disappears. The chromatids now attach to a microtubule (part of the spindle).
12.
Which phase of the cell cycle are sister chromatids separated from their partners?
Correct Answer
D. AnapHase
Explanation
Anaphase is characterized by the sister chromatids being separated at the centromere as the spindle microtubules shorten, pulling the chromatids to the opposite ends of the cell.
13.
Which phase of the cell cycle is basically the reverse of prophase?
Correct Answer
D. TelopHase
Explanation
Telophase is the opposite of prophase: The spindle disappears, the nuclear membrane will reform; the chromosomes will uncoil and lengthen. The nucleoli will reappear. The cell is NOT separated yet (only the nucleus).
14.
Which phase of the cell cycle are the two nuclei separated?
Correct Answer
E. TelopHase
Explanation
At the end of telophase, the nuclei are separated, BUT the cell is not separated yet until the end of cytokinesis.