Cell Cycle Regulation And Apoptosis Practice Test Practice Tests

Question 1

A cell completes one cell cycle every 24 hours. If the M phase lasts 1 hour and the S phase lasts 10 hours, what percentage of the total cell cycle time is spent in G1 and G2 phases combined, assuming they are equal in duration?

Accepted Answer

54.17%

Answer

45.83%

Answer

27.08%

Answer

13.00%

Question 2

During the S phase, a cell replicates its DNA. If a cell initially contains 6 picograms (pg) of DNA in G1 phase, how much DNA (in pg) will it contain after the S phase is complete?

Accepted Answer

12 pg

Answer

3 pg

Answer

6 pg

Answer

24 pg

Question 3

A population of cells is observed under a microscope. It is noted that 5% of the cells are in prophase, 2% in metaphase, 1% in anaphase, and 2% in telophase. If the total cell cycle time is 20 hours, approximately how long (in hours) does metaphase last?

Accepted Answer

0.4 hours

Answer

0.2 hours

Answer

1 hour

Answer

2 hours

Question 4

A cell line has a total cell cycle time of 18 hours. If the G1 phase lasts 6 hours, the S phase lasts 7 hours, and the G2 phase lasts 4 hours, what percentage of the cell cycle is spent in the M phase?

Accepted Answer

5.56%

Answer

11.11%

Answer

33.33%

Answer

38.89%

Question 5

A researcher is studying a cell line where the cell cycle duration is affected by temperature. At 30°C, the cell cycle takes 24 hours, while at 37°C, it takes 18 hours. If the M phase consistently lasts 1 hour at both temperatures, how much shorter (in hours) is the combined duration of G1, S, and G2 phases at 37°C compared to 30°C?

Accepted Answer

5 hours

Answer

4 hours

Answer

6 hours

Answer

7 hours

Question 6

A cell with a diploid number of 2n = 46 chromosomes undergoes mitosis. How many chromosomes will each daughter cell have after cytokinesis?

Accepted Answer

46

Answer

23

Answer

69

Answer

92

Question 7

A cell has 100 units of cyclin A at the start of S phase. Cyclin A is degraded at a rate of 5 units per minute. If Cdk1 activation requires a minimum of 50 units of cyclin A, how long will Cdk1 remain active, assuming no new cyclin A is synthesized?

Accepted Answer

10 minutes

Answer

5 minutes

Answer

15 minutes

Answer

20 minutes

Question 8

A mutation in a cell line results in a Cdk that is constitutively active, regardless of cyclin binding. If the normal phosphorylation rate of a target protein by Cdk is described by the equation $Rate = k[Cdk][Target]$, where $k = 0.05 \frac{1}{s \cdot \mu M}$, $[Target] = 10 \mu M$, and $[Cdk]$ is normally regulated between 0 and 2 $\mu M$, what is the maximum possible increase in the phosphorylation rate due to the mutation if [Cdk] is now always 2 $\mu M$?

Accepted Answer

No increase, as the Cdk is already at its maximum activity.

Answer

0.1 $\mu M/s$

Answer

1 $\mu M/s$

Answer

0.05 $\mu M/s$

Question 9

A researcher is studying a cell line where the gene encoding Wee1 kinase is overexpressed. Wee1 phosphorylates Cdk1, inhibiting its activity. If the normal Cdk1 activity is 100 units and Wee1 overexpression increases Cdk1 phosphorylation by 50%, and each unit of phosphorylation reduces Cdk1 activity by 2 units, what is the resulting Cdk1 activity?

Accepted Answer

0 units

Answer

25 units

Answer

50 units

Answer

75 units

Question 10

Which of the following mechanisms contribute to the regulation of Cdk activity?

Answer

Transcriptional regulation of Cdk genes

Answer

Cyclin binding

Answer

Phosphorylation and dephosphorylation

Answer

Binding of Cdk inhibitor proteins (CKIs)

Answer

Regulation of ribosome biogenesis

Question 11

The concentration of Cdks oscillates dramatically during the cell cycle, similar to cyclins.

Accepted Answer

True

Answer

False

Question 12

The APC/C ubiquitin ligase targets which protein for degradation to initiate sister chromatid separation?

Accepted Answer

A. Securin

Answer

B. Cyclin D

Answer

C. p53

Answer

D. Cdk2

Question 13

If a cell has accumulated significant DNA damage, what is the primary role of p53 in preventing the cell from progressing through the cell cycle? Briefly explain the mechanism.

Accepted Answer

p53 induces cell cycle arrest, allowing time for DNA repair or triggering apoptosis if the damage is irreparable.

Question 14

A cell with a mutated APC/C complex is unable to degrade Cyclin B. What is the most likely consequence of this mutation?

Accepted Answer

C. Failure to exit mitosis

Answer

A. Premature DNA replication

Answer

B. Uncontrolled cell growth

Answer

D. Increased DNA repair

Question 15

The G1 checkpoint primarily monitors chromosome attachment to the spindle apparatus.

Accepted Answer

False

Answer

True

Question 16

Which of the following are potential outcomes of p53 activation in response to DNA damage?

Answer

A. Cell cycle arrest

Answer

B. Uncontrolled cell division

Answer

C. Apoptosis

Answer

D. DNA repair

Answer

E. Increased metabolism

Question 17

During apoptosis, caspases are activated, leading to the cleavage of target proteins. If the concentration of active caspases increases exponentially over time, and the initial concentration is $C_0$, which equation best describes the concentration $C(t)$ at time $t$, assuming a growth rate constant $k$?

Accepted Answer

C. $C(t) = C_0e^{kt}$

Answer

A. $C(t) = C_0 + kt$

Answer

B. $C(t) = C_0kt$

Answer

D. $C(t) = C_0 - e^{kt}$

Question 18

Apoptosis is crucial for maintaining tissue homeostasis. If a population of cells undergoing apoptosis decreases by 50% every hour, and the initial population is 1000 cells, how many cells will remain after 3 hours? Show your calculation.

Accepted Answer

125 cells. Calculation: $1000 * (0.5)^3 = 125$

Question 19

Apoptosis plays a significant role in both development and disease. Select all the processes where apoptosis is critically involved:

Answer

A. Removal of webbing between fingers during embryonic development

Answer

B. Causing inflammation due to uncontrolled cell lysis

Answer

C. Elimination of autoreactive T cells in the thymus

Answer

D. Prevention of cancer by eliminating cells with damaged DNA

Question 20

Dysregulation of apoptosis can lead to various diseases. If the rate of apoptosis in a tissue decreases, it will always lead to cancer.

Accepted Answer

False

Answer

True

Cell Cycle Regulation And Apoptosis Practice Test Practice Tests

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Cell Cycle Regulation and Apoptosis Practice Test

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