Question 1

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to

Accepted Answer

Vinblastine interferes with the assembly of microtubules, which are important components of the mitotic spindle. Disruption of mitotic spindle formation can lead to cell cycle arrest and cell death, making A the best choice. The other options listed are not directly related to microtubule assembly.

Question 2

Use the following information to answer the questions below.
Nucleotides can be radiolabelled before they are incorporated into newly forming DNA and can therefore be assayed to track their incorporation. In a set of experiments, a student-faculty research team used labelled T nucleotides and introduced these into the culture of dividing human cells at specific times.
-Once they had determined which cells were dividing, the team wanted to use a ?non-radioactive method to track whether various physiological factors (such as food or body temperature)affected the action of the pathogen. Which of the following would be effective, simple, and safe?

Accepted Answer

Counting the frequency of cells in mitosis would be the most effective, simple, and safe method to track the incorporation of radiolabelled nucleotides as well as any physiological factors affecting the action of the pathogen. The presence of dividing cells indicates ongoing DNA replication and cell division, making it a reliable marker of cellular activity. Additionally, this method does not involve the use of radioactive materials or external markers, making it safe to use. Measuring picograms of DNA, numbers of chromosomes, numbers of chromatids, and counting newly formed plasma membranes would not provide a reliable or practical means of tracking cellular activity or physiological factors.

Question 3

In the cells of some organisms, mitosis occurs without cytokinesis. This will result in

Accepted Answer

Mitosis is the division of the nucleus into two identical daughter nuclei, while cytokinesis is the division of the cytoplasm to form two separate cells. If mitosis occurs without cytokinesis, the result is cells with more than one nucleus. This condition is called multinucleated or syncytial cells and is commonly found in skeletal muscle cells and some fungi.

Question 4

The following questions are based on the following figure.
 
-At which of the numbered regions would you expect to find cells at metaphase?

Accepted Answer

The answer of The following questions are based on the...

Question 5

The following questions are based on the following figure.
 
-MPF reaches its threshold concentration at the end of this stage.

Accepted Answer

MPF (M-phase promoting factor) reaches its threshold concentration at the end of interphase, which is stage III in the context of the cell cycle phases, leading to the cell's entry into mitosis.

Question 6

The decline of MPF activity at the end of mitosis is due to

Accepted Answer

The decline of MPF activity at the end of mitosis is due to the degradation of cyclin, which is the regulatory subunit of the MPF complex. As a result, the catalytic subunit, Cdk, is inactive without cyclin and the cell undergoes exit from mitosis.

Question 7

Use the following information to answer the questions below.
A student is looking through his light microscope (~450 X) at a squashed and stained onion root tip. Some, but not all, of the cells have clearly visible chromosome strands.
-When the cell has just completed telophase, which of the following does he see?

Accepted Answer

The answer of Use the following information to answer the...

Question 8

Use the following information to answer the questions below.
Nucleotides can be radiolabelled before they are incorporated into newly forming DNA and can therefore be assayed to track their incorporation. In a set of experiments, a student-faculty research team used labelled T nucleotides and introduced these into the culture of dividing human cells at specific times.
-The research team used the setup to study the incorporation of labelled nucleotides into a culture of lymphocytes and found that the lymphocytes incorporated the labelled nucleotide at a significantly higher level after a pathogen was introduced into the culture. They concluded that

Accepted Answer

The fact that lymphocytes incorporated the labelled nucleotide at a significantly higher level after a pathogen was introduced into the culture suggests that infection causes lymphocytes to divide more rapidly. This is a common response of the immune system to fight off infections. Option A and B are not supported by the information given. Option D may be untrue, as not all cell cultures respond to infections in the same way, and Option E is not supported by the information given.

Question 9

The following information applies to the questions below.
Several organisms, primarily protists, have what are called intermediate mitotic organization.
-These protists are intermediate in what sense?

Accepted Answer

Intermediate mitotic organization refers to the fact that these protists maintain a nuclear envelope during division, which is an intermediate step between prokaryotic binary fission (which lacks a nuclear envelope) and eukaryotic mitosis (which has a highly developed nuclear envelope). The other options are not accurate descriptions of intermediate mitotic organization.

Question 10

Use the data in the table below to answer the following questions.
The data were obtained from a study of the length of time spent in each phase of the cell cycle by cells of three eukaryotic organisms designated beta, delta, and gamma.
  
Minutes Spent in Cell Cycle Phases
-The best conclusion concerning delta is that the cells

Accepted Answer

Delta cells spend 0 minutes in the S phase and 0 minutes in the G₂ phase, which suggests that they are not actively replicating DNA or preparing for mitosis. This could indicate that they are in the G₀ phase, a resting phase in which cells are not actively dividing.

Question 11

Use the following information to answer the questions below.
A student is looking through his light microscope (~450 X) at a squashed and stained onion root tip. Some, but not all, of the cells have clearly visible chromosome strands.
-When a cell is in anaphase of mitosis, which of the following will he see?

Accepted Answer

The answer of Use the following information to answer the...

Question 12

Use the following information to answer the questions below.
A research team established similar lymphocyte cultures from a number of human donors, including healthy teenagers of both genders, patients already suffering from long-term bacterial infections, and elderly volunteers. They found that the increase in lymphocyte incorporation after pathogen introduction was slightly lower in some of the female teenagers and significantly lower in each of the elderly persons. They repeated the study with a larger number of samples but got the same results.
-What might be among the research team's conclusions?

Accepted Answer

The research team's conclusion is likely that the elderly persons demonstrated lowered immune responses. This is based on the fact that their lymphocyte incorporation after pathogen introduction was significantly lower, which suggests that their immune system is not responding as effectively as it should. The other answer choices are not supported by the information given in the passage.

Question 13

Use the following information to answer the questions below.
You observe cells under the microscope and notice that, while in telophase, small vesicles line up along the middle of the cell.
-You conclude that these cells are

Accepted Answer

The presence of small vesicles lining up along the middle of the cell during telophase is characteristic of plant cells during cytokinesis. These vesicles eventually fuse together to form the cell plate which separates the two daughter cells. Animal cells, on the other hand, typically form a cleavage furrow during cytokinesis. Bacteria, diatoms, and tumor cells do not undergo cytokinesis as multicellular organisms do, so they are not the correct answer.

Question 14

One difference between cancer cells and normal cells is that cancer cells

Accepted Answer

Cancer cells have lost their ability to respond to signals from their environment, including signals that would normally tell them to stop dividing when in close contact with other cells. This is known as the lack of density-dependent inhibition and allows cancer cells to continue dividing even when they are tightly packed together, forming tumors.

Question 15

The following information applies to the questions below.
Several organisms, primarily protists, have what are called intermediate mitotic organization.
-What is the most probable hypothesis about these intermediate forms of cell division?

Accepted Answer

The term "intermediate mitotic organization" implies that these organisms exhibit some but not all of the characteristics of normal mitosis. This suggests that they may be in the process of evolving towards complete mitosis, making option E the most probable hypothesis. The other options are less likely as they suggest complete separation or divergence from other organisms, which is not necessarily supported by the given information.

Question 16

Use the data in the table below to answer the following questions.
The data were obtained from a study of the length of time spent in each phase of the cell cycle by cells of three eukaryotic organisms designated beta, delta, and gamma.
  
Minutes Spent in Cell Cycle Phases
-Of the following, the best conclusion concerning the difference between the S phases for beta and gamma is that

Accepted Answer

The S phase is part of the cell cycle in which DNA is replicated. If there's a difference in the S phases between beta and gamma, it implies a difference in the amount of DNA being replicated. Therefore, gamma containing more DNA than beta is the most logical conclusion based on the information provided.

Question 17

Use the following information to answer the questions below.
You observe cells under the microscope and notice that, while in telophase, small vesicles line up along the middle of the cell.
-Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely

Accepted Answer

The small vesicles lining up along the middle of the cell during telophase indicate the formation of a cell plate, which is a characteristic of cytokinesis in plant cells. Animal cells typically form a cleavage furrow during cytokinesis. The presence of nuclei on either side of the cell plate further supports the hypothesis that this cell is undergoing cytokinesis. Option A and C are incorrect based on the reasons mentioned above. Option D is also incorrect because bacterial cells typically undergo binary fission, which does not involve the formation of a cell plate or nuclei. Option E is incorrect because metaphase is characterized by the alignment of chromosomes along the equatorial plane of the cell, and there is no mention of this feature in the description provided.

Question 18

Use the following information to answer the questions below.
A research team established similar lymphocyte cultures from a number of human donors, including healthy teenagers of both genders, patients already suffering from long-term bacterial infections, and elderly volunteers. They found that the increase in lymphocyte incorporation after pathogen introduction was slightly lower in some of the female teenagers and significantly lower in each of the elderly persons. They repeated the study with a larger number of samples but got the same results.
-Which of the following investigations might be most productive to show what the data on the teenagers might indicate?

Accepted Answer

Testing female teens at different times in their menstrual cycles would be most productive because hormonal fluctuations during the menstrual cycle can affect the function of lymphocytes. This could help to determine whether the slightly lower lymphocyte incorporation in some of the female teenagers is related to their menstrual cycle. The other options are less likely to provide insights into the potential reasons for the observed differences in lymphocyte incorporation.

Question 19

Use the following information to answer the questions below.
Nucleotides can be radiolabelled before they are incorporated into newly forming DNA and can therefore be assayed to track their incorporation. In a set of experiments, a student-faculty research team used labelled T nucleotides and introduced these into the culture of dividing human cells at specific times.
-Which of the following questions might be answered by such a method?

Accepted Answer

The incorporation of radiolabelled nucleotides can be used to determine the timing and duration of the S phase, as this is when DNA synthesis occurs.

Question 20

Use the following information to answer the questions below.
You observe cells under the microscope and notice that, while in telophase, small vesicles line up along the middle of the cell.
-The event that you are witnessing is

Accepted Answer

The lining up of small vesicles along the middle of the cell during telophase is characteristic of cytokinesis, which is the division of the cytoplasm that follows nuclear division in cell division. Cleavage is actually a part of cytokinesis in animal cells, where a cleavage furrow forms and eventually splits the cell into two daughter cells. Meiosis is a type of cell division that results in the formation of gametes with half the number of chromosomes, and it does not involve vesicle formation during telophase. Apoptosis is programmed cell death and does not involve cell division. Binary fission is a type of asexual reproduction seen in bacteria and some other single-celled organisms, and it does not involve vesicle formation during telophase.

Quiz 12: The Cell Cycle

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to

In the cells of some organisms, mitosis occurs without cytokinesis. This will result in

The following questions are based on the following figure. -At which of the numbered regions would you expect to find cells at metaphase?

The following questions are based on the following figure. -MPF reaches its threshold concentration at the end of this stage.

The decline of MPF activity at the end of mitosis is due to

The following information applies to the questions below. Several organisms, primarily protists, have what are called intermediate mitotic organization. -These protists are intermediate in what sense?

Use the following information to answer the questions below. You observe cells under the microscope and notice that, while in telophase, small vesicles line up along the middle of the cell. -You conclude that these cells are

One difference between cancer cells and normal cells is that cancer cells

The following information applies to the questions below. Several organisms, primarily protists, have what are called intermediate mitotic organization. -What is the most probable hypothesis about these intermediate forms of cell division?

Use the following information to answer the questions below. You observe cells under the microscope and notice that, while in telophase, small vesicles line up along the middle of the cell. -The event that you are witnessing is