AP Bio - Unit 4 Progress Check MCQ
Which of the following statements best justifies the claim that changes in the expression of ced - 9 in C. elegans can affect regulation of apoptosis in the cell?
An experiment showed that a mutation in the ced - 9 gene led to excessive cell death in C. elegans
Which of the following changes in FGFR signaling pathway is most likely to result in uncontrolled cell proliferation?
The irreversible association of FGFR proteins
Which of the following outcomes will most likely result from the inactivation of the beta-2 adrenergic receptor?
The rate of glycogen synthesis in the cell will increase
Which of the following describes a critical role of cAMP during the transduction stage of a G protein signal transduction pathway?
cAMP results in the activation of an enzyme that amplifies the signal by acting on many substrate molecules
A student used microscopy to investigate the relative lengths of the different stages of mitosis. The student prepared slides of cells isolated from a growing onion root tip and viewed the slides under a dissecting microscope. The student then made diagrams of cells that were in different stages of mitosis and counted the number of cells that were in each of those stages. The student's data are presented in Table 1 Based on the data, the percent of mitotic cells that were in metaphase is closest to which of the following?
18%
Scientists have estimated that it takes yeast cells approximately 20 hours to complete the entire cycle. Table 1 shows the amount of time in each phase of life cycle for yeast cells Stage: M G1 S G2 Hours: 2 10 5 3 Based on Table 1, what percent of the life cycle of yeast cells is spent in DNA replication?
25 percent
Which of the following steps in a signaling pathway typically occurs first once a chemical messenger reaches a target cell?
A ligand binds to the receptor
Which of the following justifies the claim that differences in components of cell signaling pathways explain the different responses to epinephrine?
Cell signaling depends on the ability to detect a signal molecule. Not all cells have receptors for epinephrine. Only cells with such receptors are capable of responding
Which of the following best describes the role of cell-to-cell communication during a response to an invasion of antigens?
Chemicals that are secreted from antigen-presenting cells then activate helper T-cells
Blood clots are formed by a positive feedback loop. Two pathways exist, the extrinsic and intrinsic pathways, which converge during clot formation. There are many clotting factors involved, most of which are proteins. Vitamin K is required for the formation of the active form of several of the clotting factors, including Factor X. Warfarin is a drug used to treat certain blood clots. Warfarin blocks the formation of the active form of vitamin K-dependent clotting factors. Based on the model, which of the following best predicts the effects of warfarin on a patient?
Factor X will not be activated, which will prevent thrombin from forming
Signal transduction may result in changes in gene expression and cell function, which may alter phenotype in an embryo. An example is the expression of the SRY gene, which triggers the male sexual development pathway in mammals. This gene is found on the Y chromosome. Which statement provides the evidence to justify the claim that signal transduction may result in an altered phenotype?
If the SRY gene is absent or nonfunctional, the embryo will exhibit female sexual development
A person's blood glucose level fluctuates during the day, as represented in Figure 1. Two hormones, insulin and glucagon, are directly involved in the regulating blood glucose level to maintain a healthy level. Insulin acts to lower the blood glucose level, and glucagon acts to increase the blood glucose level. Which of the following best predicts what will happen to the blood glucose level is the person has another meal at 5 PM?
Immediately after the meal, the blood glucose level will increase, and then insulin will be secreted to counter the increase
The epidermal growth factor receptor EGFR is a cell surface receptor. When a growth factor binds to EGFR, the receptor is activated. The activated EGFR triggers a signal transduction pathway, which leads to increased frequency of cell division Which of the following best predicts the effect of a mutation that causes EGFR to be active in the absence of a growth factor?
Increased cell division will lead to the formation of a tumor
Metformin is a drug used to treat type 2 diabetes by decreasing glucose production in the liver. AMP-activated protein kinase (AMPK) is a major cellular regulator of glucose metabolism. Metformin activated AMPK in liver cells but cannot cross the plasma membrane. By blocking AMPK with an inhibitor, researchers found that AMPK activation is required for metformin to produce an inhibitory effect on glucose production by liver cells. Which of the following best describes the component that metformin represents in a signal transduction pathway that regulates glucose production in the liver?
It is a ligand that activates the signal transduction pathway activation of AMPK
Researchers grew seedlings of corn, Zea mays, in loose and compact sand. The researchers measured the amount of time required for the cells in the growing root tips of the seedlings to double in number. The mean cell doubling times for the two groups of seedlings are shown in Figure 1 Based on the sample means, which of the following conclusion about the cells in the growing root tips of Zea mays seedlings is best supported by the results of the experiment?
More cells are produced per unit of time in the root tips growing in compact sand than in the root tips growing in loose sand
A researcher found a mutation that resulted in the PFK enzyme being unable to bind ATP to the allosteric site. Which of the following best predicts the effect of the mutation?
Negative feedback regulation does not occur, so the enzyme will be active when glycolysis is not needed
A cell culture commonly used in research was selected to study the effect of a specific virus on the timing of cell cycle phases. Two separate cultures were started, one untreated and one inoculated with the virus. Both cultures were incubated under identical conditions. After a period of time, 200 cells from each culture were observed and classified as shown in Table 1 Phase of the Cell Cycle Untreated Cells Virus Infected Cells G0 196 10 Interphase 2 40 Mitosis 2 150 which of the following most accurately describes an observation and an effect of the viral infection indicated by the data in Table 1?
Seventy-five percent of the virus infected cells are found in mitosis. The virus stimulates frequency cell division
The relative amounts of DNA present in the nucleus of a cell at four different stages of the life cycle are shown in Figure 1 Based on Figure 1, which of the following statements correctly links a stage of the cell cycle with the event occurring at that stage?
Synthesis of sufficient DNA for two daughter cells occurs in stage II
Which of the following best explains a possible mechanism that would enable the hormone to efficiently reach all of the target cells in the body?
The hormone is releases into the bloodstream where it can be transported to all cells with the correct receptors
Which of the following statements best predicts the effect of a loss of function of the insulin receptor's intracellular domain?
The storage of GLUT4 in vesicles inside the cell will increase
Which statement best predicts why a cell's progression through the cell cycle might by halted at the G1/S checkpoint?
There are not enough nucleotides available to construct new DNA
Researchers tracked the amount of DNA (measured in picograms) over time beginning with a single cell and continuing through several rounds of cell division. The researchers observed threadlike chromosomes prior to cell division. The threadlike chromosomes disappeared from view shortly after each division. The amount of DNA in picograms per cell over several rounds of cell division is shown in Figure 1 Which of the following statements is consistent with the data in Figure 1?
There is a change from 3 to 6 picograms of DNA because DNA is replicated before each round of cell division
Which of the following statements best describes a primary function of plasmodesmata?
They allow the movement of molecules from one cell to another, enabling communication between cells
The tumor suppressor protein p53 binds to DNA and activates target genes, which results in the synthesis of p21, CD95, and other proteins. The p21 protein promotes cell-cycle arrest, whereas CD95 protein promotes apoptosis Which of the following will most likely result from a loss of p53 function?
Uncontrolled cell proliferation