Unit 4 , AP BIO questions

What is the expected percent change in the DNADNA 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?

+100%

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

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

95%

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 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.

Based on the data, which of the following best represents how the mice with the implanted hESC-β cells use negative feedback to return blood glucose levels to normal if blood glucose levels increase?

Increased insulin secretion by hESC-β cells → increased glucose uptake by body cells → decreased insulin secretion by hESC-β cells

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.

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.

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.

the p53 protein regulates a cellular response to DNA damage. Based on the diagram above, which of the following best describes the role of p53 in the response to DNA damage

Phosphorylated p53 stimulates transcription of p21 , and the resulting p21 protein suppresses cell division until the DNA damage is repaired.

During mitosis, which of the following normally occurs?

Replicated chromosomes line up on the equatorial plate.

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.

The diagram above illustrates feedback control as exerted by the hormone thyroxine. Following surgical removal of the thyroid gland, the level of TSH in the blood will increase. Which of the following best explains this increase?

A decrease in thyroxine levels means a loss of inhibition to the hypothalamus and anterior pituitary, leading to increased TSH secretion

Cancer can result from a variety of different mutational events. Which of the following is LEAST likely to result in the initiation of a cancerous tumor?

A defect in a cell-cycle checkpoint prevents a cell from entering the S phase.

In mammals, an increase in the concentration of sodium in the blood triggers the release of antidiuretic hormone (ADH) from the pituitary gland. As the concentration of sodium in the blood returns to previous levels, the release of ADH from the pituitary gland is reduced. Based on the information presented, which of the following describes the most likely role of ADH in maintaining blood osmolarity?

ADH promotes an increase in the movement of water into the bloodstream.

The endocrine system incorporates feedback mechanisms that maintain homeostasis. Which of the following demonstrates negative feedback by the endocrine system?

After a meal, blood glucose levels become elevated, stimulating beta cells of the pancreas to release insulin into the blood. Excess glucose is then converted to glycogen in the liver, reducing blood glucose levels.

The vertebrate forelimb initially develops in the embryo as a solid mass of tissue. As development progresses, the solid mass near the end of the forelimb is remodeled into individual digits. Which of the following best explains the role of apoptosis in remodeling of the forelimb?

Apoptosis involves the regulated activation of proteins in specific cells of the developing forelimb that leads to the death of those cells.

The model shown in the figure represents the role of two hormones, calcitonin and parathyroid hormone (PTH), in maintaining normal blood calcium levels in humans. If a dietary change results in an increase in blood calcium concentration above normal levels, which of the following is the most likely effect on calcium homeostasis?

Calcitonin levels will rise, thus promoting the deposit of calcium into bones.

Glycogen synthetase kinase 3 beta is a protein kinase that has been implicated in many types of cancer. Depending on the cell type, the gene for glycogen synthetase kinase 3 beta (GSK3β)(GSK3β) can act either as an oncogene or as a tumor suppressor. Which of the following best predicts how GSK3βGSK3β mutations can lead to the development of cancer?

Cells with inactive GSK3βGSK3β 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.

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.

Based on the experimental results, which of the following describes the most likely defect in muscle cells of patients with type 2 diabetes?

IRS-1 activation is reduced at high insulin concentrations.

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 is true of mitosis?

It maintains the same chromosome number in the daughter cells as in the parent cell.

Cancer cells behave differently than normal body cells. For example, they ignore signals that tell them to stop dividing. 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 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.

DNA 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 data in Figure 2, which of the following best justifies the researchers' claim that hESC-β implants can functionally replace the mouse's naturally occurring β-cells?

The mouse with an hESC-β implant successfully regulated blood glucose levels after STZ treatment but not after the implant was removed.

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.

Which of the following is a valid interpretation of the experimental results that explains how individuals with type 2 diabetes differ from individuals without diabetes?

The relatively low levels of glucose uptake in individuals with type 2 diabetes indicate that mobilization of GLUT4 to the cell surface is reduced in muscle cells of those individuals.

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.

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

A human cell in prophase of mitosis can be distinguished from a human cell in prophase I of meiosis by the presence of

paired homologous chromosomes in the meiotic cell

Based on the information presented, which of the following genetic changes in an individual without diabetes is most likely to result in a disrupted cellular response to insulin signaling similar to that of an individual with type 2 diabetes?

A deletion in the gene encoding the insulin receptor that removes only the cytoplasmic domain of the protein

The graph above shows changes in glucagon and insulin secretions at different concentrations of blood glucose. Which of the following feedback mechanisms is best supported by the data?

A low glucose level causes the release of glucagon, which stimulates the release of more glucose from tissues, which in turn lowers the amount of glucagon being released.

Damaged tissue releases chemicals that activate platelets and stimulate the formation of blood clots. Which of the following predictions about the activity of platelets best describes a positive feedback mechanism?

Activated platelets release chemicals that activate more platelets.