LS 7C Midterm 1

1. Resting potential is generated mainly by the outward movement of K+ ions from inside the cell. 2. The voltage changes shown in the figure are measured just across the plasma membrane 3. The changes in voltage seen at #2 and #4 in the figure are caused by similar movements, in the same direction, of the same types of ions across the membranes. 4. The trace in the figure is following the voltage change as it moves down the axon. 5. The voltage change shown in the figure is an all-or-nothing response. 6. Different ion channels are responsible for generating the voltage change seen at #2 and #4 in the figure. 7. All voltage changes along the plasma membrane of an axon have the characteristic shape shown above. 8. The changes in voltage shown in the figure are due to ligand-gated ion channels opening and closing along the axon. 9. An EPSP of sufficient strength to reach threshold occurred at #1 on the figure. 10. A membrane that has no K+ channels will have a resting membrane potential that is higher than the one shown on the figure.

1. true 2.false 3.false 4.false 5.true 6.true 7.true 8.false 9.true 10.true

When a person has a few drinks containing alcohol, they often feel the need to urinate. This response suggests interplay between alcohol and antidiuretic hormone (ADH). Which of the following could explain how alcohol and ADH interact? (note: ADH causes a decrease in urine production) Alcohol facilitates the binding of ADH to receptors in the brain, so individuals "feel" the need to urinate. Alcohol decreases the release of ADH. Alcohol increases the release of ADH. Alcohol inhibits the binding of ADH to receptors in the brain, so individuals "feel" the need to urinate.

Alcohol decreses the release of ADH.

Many birth-control pills release a constant amount of synthetic estradiols and progesterone for 21 days, followed by 7 days when no hormones are ingested. Which of the following statements MOST accurately describes the effects of birth-control pills? The 7 days with no hormones does not allow a thick enough uterine lining to form so a fertilized oocyte cannot implant. Birth-control pills maintain constant levels of estrogens and/or progesterone so there is no surge in LH and ovulation does not occur. Birth-control pills maintain constant levels of estrogens and/or progesterones and mask the release of the oocyte from the follicle. Birth-control pills inhibit the development of the uterine lining so implantation of a fertilized oocyte cannot occur.

Birth-control pills maintain constant levels of estrogens and/or progesterone so there is no surge in LH and ovulation does not occur.

If a mutation occurred in the cadherin gene so that the cytoplasmic domain no longer attached to the cytoskeleton, which of the following would occur? Cadherins in hemidesmosomes would no longer be anchored to intermediate filaments. Cadherins in adherens junctions would no longer be anchored to microtubules. Cadherins in desmosomes would no longer be anchored to intermediate filaments. Cadherins in desmosomes would no longer be anchored to microfilaments.

Cadherins in desmosomes would no longer be anchored to intermediate filaments.

The magnitude of the action potential is correlated with the strength of the stimulating input. False True

False

A key difference between hormonal regulation of the reproductive systems of males and females is that: LH and FSH are released cyclically in females but nearly continuously in males. LH is released in males and FSH is released in females. LH and FSH are released only in females. LH is released continuously in males and FSH is released cyclically in females. LH and FSH are released only in males.

LH and FSH are released cyclically in females but nearly continuously in males.

Some people have low levels of calcium circulating in the blood, a condition known as hypocalcemia. While for many this disorder has little to no effect, for some it can be life-threatening. How could low levels of calcium harm an individual? Low levels of calcium would not have any effect on synaptic transmission. Low levels of calcium would result in fewer signals sent between the pre- and postsynaptic cell. Low levels of calcium would cause sustained depolarization of the presynaptic cell.

Low levels of calcium would result in fewer signals sent between the pre- and postsynaptic cell.

Imagine that you are talking with one of your friends about your biology course. He states that the somatic nervous system is subdivided into sympathetic and parasympathetic components, and is responsible for involuntary responses. Is this statement correct? No, although the somatic nervous system controls involuntary responses, it is the autonomic nervous system that is subdivided into parasympathetic and sympathetic components. No, although the somatic nervous system does have both sympathetic and parasympathetic subdivisions, it is responsible for voluntary responses. No, the somatic nervous system is responsible for voluntary responses, and is not subdivided into sympathetic and parasympathetic components. Yes, this statement is correct. The somatic nervous system has both sympathetic and parasympathetic components and controls involuntary responses.

No, the somatic nervous system is responsible for voluntary responses, and is not subdivided into sympathetic and parasympathetic components

What effect does the nervous system have on the heart rate? Stimulation by sympathetic nerves sets the resting heart rate of the pacemaker cells in the SA node. Stimulation by sympathetic nerves causes the pacemaker cells of the AV node to depolarize more rapidly than the pacemaker cells of the SA node. The nervous system does not directly affect the heart rate. Stimulation by parasympathetic nerves causes the heart rate to slow down. Stimulation by either the sympathetic or parasympathetic nerves causes pacemaker cells in the SA node to depolarize more slowly.

Stimulation by parasympathetic nerves causes the heart rate to slow down

When iodine intake is too low, production of _____ by the anterior pituitary gland _____. triiodothyronine; decreases TSH; increases thyroxine; decreases thyroxine; increases TSH; decreases

TSH; increases

Suppose there is a mutation in a laminin-binding integrin gene that causes a loss of function in the cytoplasmic domains of the integrin. Which of the following would you expect to observe as a result of this mutation? Cell adhesion to laminin would decrease, but laminin-meditated gene expression would remain the same. The integrin would function normally because the cytoplasmic domain is not responsible for binding to laminin. The integrin would be unable to signal the cytoplasm when it had bound to laminin. Tissues would be weakened because the integrin could no longer associate with microfilaments in adherens junctions.

The integrin would be unable to signal the cytoplasm when it had bound to laminin.

Phosphatases are a family of enzymes that remove phosphate groups from specific proteins; these phosphate groups had been added to the proteins by protein kinases. Vanadate is an inhibitor of phosphatases in eukaryotic cells. What effect would vanadate have on the response of cells to signals received by receptor kinases? The response of the cell would be shorter than it normally would. The response of the cell would last longer than it normally would. The signal would still bind the receptor, so there would be no effect.

The response of the cell would last longer than it normally would.

Vascular endothelial growth factor (abbreviated VEGF and pronounced "Veg-F") is a peptide signaling molecule related to platelet-derived growth factor. VEGF is important in the formation of the circulatory system because its signaling pathway causes the formation of blood vessels in developing embryos during normal development. Tumors also produce and secrete VEGF, causing the formation of new blood vessels that supply these tumors. Given what you know about the different kinds of cell signaling and VEGF, which one of the following statements is TRUE? VEGF is an endocrine-signaling molecule because it circulates through the bloodstream inside of platelets. VEGF is an endocrine-signaling molecule because it is released from platelets into the bloodstream and is carried throughout the body, causing widespread activation of platelet-derived growth factor receptors on cells in a variety of tissues. VEGF is a paracrine signaling molecule because it binds to receptors on cells at the site where new blood vessels are needed.

VEGF is a paracrine signaling molecule because it binds to receptors on cells at the site where new blood vessels are needed.

Kisspeptin is a protein in humans that has an important role in initiating secretion of the releasing factor gonadotropin-releasing hormone (GnRH). Endocrinologists are finding that the protein kisspeptin and its receptor are central to sexual maturation at puberty. Neurons that release kisspeptin carry estrogen receptors. If this is a negative feedback system, high levels of estrogen would be expected to: neither increase nor decrease kisspeptin synthesis because steroid hormones do not affect protein synthesis. decrease kisspeptin synthesis. increase kisspeptin synthesis.

decrease kisspeptin synthesis.

Which of the following is an example of the effector's role in maintaining homeostasis? increased sweating on a hot summer day increased body temperature during a workout decrease in body temperature on a cold day vasodilation on a cold winter day

increased sweating on a hot summer day

In many cells, the adhesion to the extracellular matrix through integrins causes the activation of kinases in the cytoplasm. This suggests that: integrins are kinases. integrins promote the activation of signal-transduction pathways. extracellular matrix proteins are receptors and integrins are ligands.

integrins promote the activation of signal-transduction pathways.

Imagine you created a toxin such that when a neuron fired an action potential, the toxin would bind immediately to the sodium-potassium pump at the top of the action potential, but the sodium and potassium channels would still function. What process(es) would be affected? maintaining resting potential maintaining resting potential and returning to resting potential after the hyperpolarization phase of an action potential the hyperpolarization phase of an action potential the depolarization phase of an action potential returning to resting potential after the hyperpolarization phase of an action potential

maintaining resting potential and returning to resting potential after the hyperpolarization phase of an action potential

Macrophage cells undergo a process called phagocytosis in which material is brought into a cell in the form of membrane vesicles and then transported along microtubules toward the cell center. Assuming that the centrosome is near the cell center, you can predict that these vesicles are moving to the _____ end of microtubules using the motor protein _____. plus end; kinesin plus end; dynein minus end; kinesin minus end; dynein

minus end; dynein

An interneuron may receive multiple stimuli from the same sensory neuron over a very short period of time. The firing rate of the receiving neuron is proportional to the number of signals received from the sensory neuron over time. Of which of the following is this an example? hyperpolarization temporal summation spatial summation action potential

temporal summation

Which of the following is an example of a negative feedback altering homeostatic control? a person's heart rate drops as she runs a person shivering as temperatures rise on a hot summer day the production of oxytocin (a hormone) increases as oxytocin levels rise in the body the concentration of salt in urine increases after eating a large bag of salty chips

the concentration of salt in urine increases after eating a large bag of salty chips

Some researchers have suggested that obesity is due to a change in "set point" in the brain that is related to the number of calories a person needs, therefore people eat more than they need and gain weight. Permanently raising the set point would involve a permanent change in which of the following? the sensor the stimulus the response the effector

the sensor

Dilated pupils, inhibited digestive activity, increased respiratory rate, and release of glucose from the liver are all signs of activity of: both divisions of the autonomic nervous system. the sympathetic division of the autonomic system. the parasympathetic division of the autonomic system. the somatic nervous system.

the sympathetic division of the autonomic system