Cell Signaling Test

The illustration above depicts a neuromuscular junction of a patient with an autoimmune disorder. Acetylcholine is a stimulatory neurotransmitter. Which of the following would be the most likely result of the continued presence of the antibody?

A decrease in action potentials in the muscle, causing muscle weakness and fatigue.

Based on the model, which of the following mutations is most likely to result in a cell that will generate a cancerous tumor?

A mutation in the gene encoding G-PIP that results in a nonfunctional protein.

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.

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.

Based on the model presented, which of the following statements expresses the proper relationship between osmolarity, ADH release, and urine production?

As tissue osmolarity rises, more ADH is released, causing less water to be excreted as urine.

One important stimulus in the control of breathing is an increase in blood CO2 concentration, which is detected as a decrease in blood pH. Which of the following best describes the physiological response to an overall increase in cellular respiration in the body?

In response to low blood pH, the pH sensors send a signal to the brain, which then sends a signal to the diaphragm, resulting in an increased rate of breathing to help eliminate excess blood CO2 .

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.

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.

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.

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.

Which of the following representations of the movement of calcium, sodium, and potassium ions best shows how an action potential is transmitted to the postsynaptic neuron?

Ca on left, Na on top right, and K on bottom right

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.

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.

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.

Cortisol is a hormone produced in response to stress, including starvation, in humans. Which of the following is most likely an immediate effect of a starvation-induced increase in cortisol secretion?

Increased mobilization of fatty acids from fat cells.

A pathogenic bacterium has been engulfed by a phagocytic cell as part of the nonspecific (innate) immune response. Which of the following illustrations best represents the response?

Phagocytic cell - lysosome

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.

Which of the following best describes what occurs when the action potential reaches a chemical synapse at the end of an axon?

The action potential causes a release of neurotransmitters that travel across the synapse.

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.

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.

The transmission of information from sensory neurons to interneurons typically involves the

release of chemical messengers into the space between the axon of the sensory neuron and the plasma membrane of the interneuron.

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.

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.

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.

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.