Unit 4: Cell Communication & Cell Cycle Ap Biology Quiz

What is the expected percent change in the DNA content of a typical eukaryotic cell as it progresses through the cell cycle from the start of the G1 phase to the end of the G2 phase?

+100%

If chemical signals in the cytoplasm control the progression of a cell to the M phase of the cell cycle, then fusion of a cell in G1 with a cell in early M phase would most likely result in the-

condensation of chromatin in preparation of nuclear division in both cells

Which of the following does not occur during mitosis?

condensation of the chromosomes

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

continue to divide even when they are tightly packed together.

Using the yeast signal transduction pathways, both types of mating cells release the mating factors. These factors bind to specific receptors on the correct cells,-

which induce changes in the cells that lead to cell fusion

Which of the following diagrams best represents hormone-activated gene expression?

A

Figure 1 shows the number of chromosomes observed in an actively dividing human cell at each stage of cell division. Which of the following presents a correct interpretation of the changes in chromosome number depicted in Figure 1 ?

Chromosomes enter metaphase containing two chromatids attached by a centromere. During anaphase, the chromatids are separated, each becoming a chromosome. Cytokinesis distributes the chromosomes into two separate cells.

Figure 1. The relative concentrations of both the cyclin and CDK components of MPF Maturation promoting factor, MPF, is a cyclin-CDK complex that catalyzes the phosphorylation of other proteins to start mitosis. The activity level of MPF is dependent on the relative concentrations of the cyclin and CDK components of MPF (Figure 1). Based on Figure 1, which of the following describes the role of cyclin in the regulation of the cell cycle?

During M phase, the cyclin level peaks, resulting in an increased binding frequency with CDK .

Which of the following is the best explanation for the fact that most transduction pathways have multiple steps?

Multiple steps provide for greater possible amplification of a signal.

A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. How many picograms would be found at the end of S and the end of G₂?

16:16

Within a forest ecosystem, there is a large amount of diversity among members of a warbler species. Of the following stages of meiosis illustrated for a typical cell, which contributes most to diversity among the warblers?

C

Which of the following best describes the role of mitosis in the cell cycle?

Distributing replicated chromosomes to daughter nuclei

The process depicted in the image above is best summarized by which of the following descriptions?

During meiosis, crossing over leads to recombination of alleles between homologous chromosomes.

Cell communication is critical for the function of both unicellular and multicellular eukaryotes. Which of the following is likely true of cell signaling?

Similar cell signaling pathways in diverse eukaryotes are evidence of conserved evolutionary processes.

The relative amount of DNA in a cell at various stages of the cell cycle is shown in Figure 1 . Which of the following best describes how the amount of DNA in the cell changes during M phase?

The amount of DNA is halved as the cell divides into two daughter cells.

Type 1 diabetes results from the destruction of insulin-producing cells in the pancreas. Individuals with type 1 diabetes produce insufficient amounts of insulin, a hormone that regulates the concentration of glucose in the blood. Which of the following best explains how treatment with a drug that stimulates the production of insulin receptors on target cells will affect the insulin signaling pathway in an individual with type 1 diabetes?

The drug will have little or no effect on the signaling pathway because the receptors will not be activated in the absence of insulin.

Which of the following statements best describes how a growth factor stimulates cell division from outside a cell?

The growth factor binds to receptors on the cell surface, initiating a signal transduction pathway that activates specific target genes.

What is most likely to happen to an animal's target cells that lack receptors for local regulators?

They might not be able to multiply in response to growth factors from nearby cells.

What is a cleavage furrow?

a groove in the plasma membrane between daughter nuclei

The mechanism of action of many common medications involves interfering with the normal pathways that cells use to respond to hormone signals. Which of the following best describes a drug interaction that directly interferes with a signal transduction pathway?

A medication enters the target cell and inhibits an enzyme that normally synthesizes a second messenger.

The figure above shows a model of a ligand precursor being cleaved to produce an active ligand that binds to a specific receptor. Which of the following is most likely to reduce the binding of the active ligand to its receptor?

A mutation in the receptor gene that causes a substitution of a charged amino acid for a nonpolar amino acid in the ligand binding site of the receptor

Epinephrine is a protein hormone found in many animals. Epinephrine stimulates a signaling pathway that results in the breakdown of glycogen to glucose in the liver cells. Which of the following describes the initial steps in the process whereby epinephrine stimulates glycogen breakdown?

Epinephrine binds to a cell-surface receptor; the activated receptor stimulates production of the second messenger, cAMP.

Many human cells can be stimulated to divide by hormonelike growth factors that bind to receptor proteins (R) on the plasma membrane and trigger an internal signal-transduction cascade. In many cases, however, the process of contact inhibition prevents mitosis when cells are in direct contact with one another. Contact inhibition occurs when proteins called cell adhesion molecules (CAMs) interact, causing them to change shape so that the growth-factor signaling proteins that normally associate with CAMs are replaced by another protein, called M. Both pathways are depicted in the figures below. Which of the following statements accurately uses the information presented to support the hypothesis that interruption of M function in a single body cell can result in cancer?

Growth-factor signaling can trigger mitosis in cells that are in direct contact with other cells.

A researcher is conducting an experiment in which cells in different phases of the cell cycle are fused together. The researcher then records what happens to the nuclei of the resulting cell (Table 1). TABLE 1. COMBINATIONS OF CELLS THAT WERE FUSED AND THE PHASE OF NUCLEI IN THE RESULTING CELL Which of the following research questions is best addressed by the experiment?

How do chemical messengers affect a cell's transition between the phases of the cell cycle?

In a certain signal transduction pathway, the binding of an extracellular molecule to a cell-surface protein results in a rapid increase in the concentration of cyclic AMP inside the cell. The cyclic AMP binds to and activates cytosolic enzymes that then activate other enzymes in the cell. Which of the following statements best describes the role of cyclic AMP in the signal transduction pathway?

It acts as a second messenger that helps relay and amplify the signal within the cell.

Which of the following occurs in all species of living organisms and may lead to an increase in genetic variation?

Mutations in the genome

A researcher examining a root tip observes a plant cell with condensed sister chromatids, kinetochores with attached microtubules, and individual chromosomes that are aligned at the equatorial plate of the cell. Which of the following best describes what the next process will be in the cell?

Paired chromatids will separate, and the new daughter chromosomes will move toward opposite poles of the cell.

Based on the model of eukaryotic cell cycle regulation shown in the figure, which of the following best describes the effect of a drug that blocks the production of the mitotic cyclin?

The cell would be prevented from entering mitosis, and the cell would stop dividing.

The relative amount of DNA in a cell at various stages of the cell cycle is shown in Figure 1 . Which of the following best describes how the amount of DNA in the cell changes during M phase?

The amount of DNA is halved as the cell divides into two daughter cells.

Figure 1 shows a model of a signal transduction cascade, initiated by the binding of a ligand to the transmembrane receptor protein A. A DNA mutation changes the shape of the extracellular domain of transmembrane receptor protein A produced by the cell. Which of the following predictions is the most likely consequence of the mutation?

The molecule that normally binds to protein A will no longer attach, deactivating the cellular response.

Researchers studying cell cycle regulation in budding yeast have observed that a mutation in the CDC15 gene causes cell cycle arrest in telophase when the yeast cells are incubated at an elevated temperature. Which of the following statements best predicts the effect of the cell cycle arrest on proliferating yeast cells?

The yeast cells will replicate their chromosomes but will fail to complete cytokinesis.