Cell Growth And Division (Mitosis)

1. Which phase of the cell cycle is characterized by the chromosomes all gathering in a plane across the middle of the cell?

Interphase

Prophase

Metaphase

Anaphase

Telophase

Chromosomes MEET in the Middle during METaphase

Explanation

Chromosomes MEET in the Middle during METaphase

2. At the start of mitosis a chromosome is made up of two:

Centromeres

Centrioles

Chromatids

Spindles

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.

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.

3. Which of the following occurs during the S phase of the cell cycle?

The genetic material is duplicated.

A cell grows in size.

The number of organelles increases.

The cytoplasm divides in two.

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.

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.

4. Which phase of the cell cycle completes the division of a cell?

Interphase

Prophase

Metaphase

Anaphase

Telophase

Cytokinesis

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.

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.

5. Which phase of the cell cycle is basically the reverse of prophase?

Interphase

Metaphse

Anaphase

Telophase

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).

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).

6. Which phase of the cell cycle are chromosomes first visible?

Interphase

Prophase

Metaphase

Anaphase

Telophase

Chromosomes are NOT visible during interphase.

Explanation

Chromosomes are NOT visible during interphase.

7. Which phase of the cell cycle are sister chromatids separated from their partners?

Interphase

Prophase

Metaphase

Anaphase

Telophase

Cytokinesis

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.

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.

8. Which of the following is NOT an advantage of asexual reproduction?

Increases genetic diversity

Simple and efficient

Produces large number of offspring quickly

Requires one parent

Asexual reproduction will produce the organisms with the SAME genetic code -- no diversity!

Explanation

Asexual reproduction will produce the organisms with the SAME genetic code -- no diversity!

9. 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?

Parts of the tarantula stretched as it grew larger.

The tarantula ate food and water.

The total number of cells in the tarantula increased.

The tarantula cells all grew larger.

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.

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.

10. Which phase of the cell cycle are the two nuclei separated?

Interphase

Prophase

Metaphase

Anaphase

Telophase

At the end of telophase, the nuclei are separated, BUT the cell is not separated yet until the end of cytokinesis.

Explanation

At the end of telophase, the nuclei are separated, BUT the cell is not separated yet until the end of cytokinesis.

11. 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.

156; 78

78;78

78; 156

39;78

78;39

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.

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.

12. 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?

It is only a coincidence; many organisms have an odd number of chromosomes.

Chromosomes double each time a cell divides; so after the first division, the number will always be even.

The diploid number represents a pair of chromosomes -- one from each parent -- so it will always be an even number.

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.

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.

13. Which phase of the cell cycle does the nuclear membrane breaks down?

Interphase

Prophase

Metaphase

Anaphase

Telophase

Cytokinesis

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).

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).

14. 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?

There is a direct relationship between temperature and developmental time of flies

The rate of cell division is faster at the increased temperature.

At a temperature of 36 C, the rate will be half the rate of 18 C (25.1 hours).

All of the choices are correct.

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.

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.