Biology test unit 4

The cell cycle of yeast cells grown in the nutrient-poor environment is approximately what percent of the cell cycle of yeast cells grown in the nutrient-rich environment?

168

Which of the following best predicts how GSK3β mutations can lead to the development of cancer?

Cells with inactive GSK3β fail to trigger apoptosis.

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.

A researcher has identified a compound that reverses the effect of drug XX. Based on Figure 3, which of the following best explains how the compound acts in the pathway to reverse the effects of drug XX?

Correct. Drug XX activates complex BB, which inhibits molecule CC and thus cellular division. Reversing the effect of drug XX requires the inhibition of complex BB.

Based on Figure 1, what percent of the time required to complete a full cycle do the cells typically spend in interphase?

Correct. Interphase is composed of the G1, SS, and G2 phases. Based on Figure 1, the cells typically spend 19 hours in interphase and require 20 hours total to complete one full cycle. Therefore, 1920×100=95%.

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 G1G1 phase to the end of the G2G2 phase?

Correct. The DNA of a typical eukaryotic cell is replicated in the SS phase of the cell cycle, which occurs between the G1 and G2 phases. DNA replication typically results in a 100% increase in the DNA content of a cell.

Which of the following statements best explains Delta's role in regulating cell communication through the Notch signaling pathway?

Delta restricts cell communication to short distances within a developing embryo.

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

Distributing replicated chromosomes to daughter nuclei

Based on Figure 1, which of the following describes the role of cyclin in the regulation of the cell cycle?

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

Based on Figure 1, which of the following best explains how exercise causes blood glucose levels to rise?

Epinephrine activates alpha cells, causing the release of glucagon, and inhibits beta cells, blocking the release of insulin.

Figure 1 shows a model of the endocrine signaling pathway that regulates ovulation. Which of the following observations would provide evidence of a positive feedback mechanism in this system?

Estrogen from the ovaries stimulates the hypothalamus and anterior pituitary to secrete more GnRHGnRH, LHLH, and FSHFSH.

A researcher claims that the epinephrine signaling pathway controls a catabolic process in muscle cells. Which of the following statements best helps justify the researcher's claim?

Glycogen phosphorylase catalyzes the conversion of glycogen to glucose-1-phosphate.

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?

Based on Figure 1, which of the following statements best describes the epinephrine signaling pathway?

In involves enzymes activating other enzymes.

Which of the following patterns is shown by the data?

In mutant 3 cells, more time is spent in prophase/prometaphase than in the later stages of mitosis.

Which of the following statements best describes the role of adenylyl cyclase in the epinephrine signaling pathway?

It accelerates the production of a second messenger.

Which of the following statements best describes the role of cyclic AMPAMP 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 best supports the claim that ethylene initiates the signal transduction pathway that leads to ripening of fruit?

Loss-of-function mutations in ethylene receptors result in changes to the ripening process.

Air is less dense at very high elevations, so less oxygen is available than in the denser air at sea level. Based on the model in Figure 1, if a person travels from sea level to a high elevation location, which of the following correctly predicts the response to the decreased blood oxygen level?

More erythropoietin will be secreted from the kidneys, increasing production of erythrocytes.

Cyclic AMPAMP phosphodiesterase is an enzyme that catalyzes the conversion of cyclic AMPAMP to a different molecule. Which of the following best predicts the effect of inhibiting cyclic AMPAMP phosphodiesterase in a muscle cell stimulated by epinephrine?

Phosphorylase kinase will remain active because protein kinase A will no longer be deactivated.

In flowering plants, plasmodesmata are narrow channels through cell walls that connect the cytoplasms of adjacent cells. An explanation of how plant cells communicate across cell walls will most likely refer to the diffusion through plasmodesmata of which of the following?

Small, water-soluble molecules

Which of the following provides correct information about cell signaling that supports the claim?

The SRYSRY gene produces a protein that binds to specific regions of DNADNA in certain tissues, which affects the development of these tissues.

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.

Which of the following conditions will most likely cause a normal body cell to become a cancer cell?

The environment contains mutagens that induce mutations that affect cell-cycle regulator proteins.

Which of the following statements best predicts the effect of a mutation that results in a loss of the glucocorticoid receptor's ligand binding function?

The glucocorticoid receptor will remain associated with the accessory proteins.

Which of the following outcomes will most likely result from the irreversible binding of GDPGDP to the G protein?

The intracellular concentration of glycogen will increase.

A DNADNA mutation changes the shape of the extracellular domain of transmembrane receptor protein AA produced by the cell. Which of the following predictions is the most likely consequence of the mutation?

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

Based on the information provided, which of the following best justifies the claim that osteocalcin is a hormone?

The osteoblasts in the bone secrete osteocalcin, which causes cells in the pancreas to change their activity.

Vertebrate immune responses involve communication over short and long distances. Which of the following statements best helps explain how cell surface proteins, such as MHCMHC proteins and T cell receptors, mediate cell communication over short distances?

The proteins interact directly with proteins on the surfaces of other cells.

Argatroban is a competitive inhibitor of thrombin. Which of the following effects on the coagulation cascade is most likely to result from inhibiting thrombin activity with argatroban?

The rate of fibrin formation will decrease.

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.