Final Exam Practice Questions

Question 1

The kinases in the MAP kinase pathway are constantly active. Which condition would be most likely to turn off this abnormally active signaling pathway?
A. The addition of a drug that prevents the phosphorylation of the receptor kinase.
B. The addition of a drug that increases the binding affinity of Ras for MAP kinase enzymes in the cytoplasm.
C. The addition of a drug that prevents the dimerization of the receptor kinase.
D. The addition of a drug that prevents the final kinase from interacting with its target protein in the nucleus.

Answer 1

D. The addition of a drug that prevents the final kinase from interacting with its target protein in the nucleus.

Question 2

Epithelial cells of the small intestine have finger-like membrane extensions, known as microvilli, that are supported by the actin cytoskeleton. Microvilli located at the apical surface of intestinal epithelial cells are responsible for:
A. increased adhesion to the extracellular matrix to strengthen the tissue.
B. increased surface area for nutrient absorption of digested food.
C. increased communication between cells.
D. increased rates of cell division in response to signaling molecules.

Answer 2

B. increased surface area for nutrient absorption of digested food.
- a greater surface area increases the amount of membrane transporters embedded on the cell membrane

Question 3

Kisspeptin is a signal protein in humans that initiates the secretion of gonadotropin-releasing hormone (GnRH) from neurons found in the hypothalamus. Endocrinologists are finding that kisspeptin and its receptor are important for sexual maturation at puberty. Neurons that release kisspeptin contain cytosolic estrogen receptors and respond to high levels of estrogen by decreasing kisspeptin secretion. Given what you know about cell signaling and signal molecules, which statement is true?
A. Estrogen activates a receptor tyrosine kinase.
B. High levels of GnRH will increase Kisspeptin synthesis
C. Kisspeptin synthesis will increase when estrogen levels are high.
D. Receptors for kisspeptin would be found on the plasma membrane of cells of the hypothalamus

Answer 3

D. Receptors for kisspeptin would be found on the plasma membrane of cells of the hypothalamus
- because kisspeptin is a signal protein, it is unable to cross the plasma membrane by simple diffusion, which requires activation of a cell surface receptor

Question 4

In a study of tadpole coloration, you noticed that a certain percentage of tadpoles in a population displayed a decreased ability to shift from dark coloration at night to light coloration during the day. These individuals were studied and found to have the normal number of melanophores and these melanophores produced normal amounts of melanin pigment granules. You remember reading that pigment granule transport in melanophores involves the cytoskeleton.
Which part of the cytoskeleton would you suggest investigating as a potential source of the faulty color adjustment in these tadpoles?
A. microtubules
B. intermediate filaments
C. microfilaments

Answer 4

A. microtubules
- melanophores are moved along microtubules kinesin and dynein during the color shifts in amphibian epithelial cells

Question 5

Imagine you created a toxin such that binds to the sodium-potassium pump. The toxin binds immediately to the sodium-potassium pump at the peak of the action potential but does not alter the function of voltage-gated sodium and potassium channels.

Which of the processes would the toxin prohibit in the neuron? Select all that apply.

• the hyperpolarization phase of an action potential
• returning to resting potential after the hyperpolarization phase of an action potential
• maintaining resting potential
• the depolarization phase of an action potential
• the repolarization phase of an action potential

Answer 5

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

Question 6

The outward movement of K+ ions from inside a neuron _____ (mark all that apply)

• generates excitatory postsynaptic potentials
• establishes resting membrane potential
• generates resting membrane potential
• repolarizes the membrane potential

Answer 6

• establishes resting membrane potential
• generates resting membrane potential
• repolarizes the membrane potential

Question 7

An interneuron may receive multiple stimuli from multiple sensory neurons over a very short period of time. When the firing rate of the receiving neuron is proportional to the number of signals received from multiple sensory neurons at a fixed moment in time, which process is this an example?

A. spatial summation
B. hyperpolarization
C. action potential
D. temporal summation

Answer 7

A. spatial summation

Question 8

Constricted pupils, increased digestive activity, decreased respiratory rate, and uptake of glucose by the liver are all signs of activity of:

A. both divisions of the autonomic nervous system
B. the parasympathetic division of the autonomic system
C. the somatic nervous system
D. the sympathetic division of the autonomic system

Answer 8

B. the parasympathetic division of the autonomic system

Question 9

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?

A. Low levels of calcium would not have any effect on synaptic transmission
B. Low levels of calcium would cause sustained depolarization of the presynaptic cell.
C. Low levels of calcium would result in fewer chemical signals sent between the presynaptic and postsynaptic cell.

Answer 9

C. Low levels of calcium would result in fewer chemical signals sent between the presynaptic and postsynaptic cell.

Question 10

Which of the scenarios will most likely trigger an action potential? Select all that apply.

• an excitatory postsynaptic potential (EPSP) and an inhibitory postsynaptic potential (IPSP) of equal magnitude arriving simultaneously on the postsynaptic cell (cancellation)
• single excitatory postsynaptic potentials (EPSPs) arriving simultaneously at several different synapses (spatial summation) on the postsynaptic cell
• multiple excitatory postsynaptic potentials (EPSPs) arriving close in time at a single synapse (temporal summation) on the postsynaptic cell
• an excitatory postsynaptic potential (EPSP) and an inhibitory postsynaptic potential (IPSP) arriving simultaneously on the postsynaptic cell that when spatially summed exceed threshold potential

Answer 10

• single excitatory postsynaptic potentials (EPSPs) arriving simultaneously at several different synapses (spatial summation) on the postsynaptic cell
• multiple excitatory postsynaptic potentials (EPSPs) arriving close in time at a single synapse (temporal summation) on the postsynaptic cell
• an excitatory postsynaptic potential (EPSP) and an inhibitory postsynaptic potential (IPSP) arriving simultaneously on the postsynaptic cell that when spatially summed exceed threshold potential

Question 11

Kisspeptin is a signal protein that, in humans, 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 cytosolic estrogen receptors and are under negative feedback control.

Which of the following statements is true?

A. Receptors for kisspeptin will be found in cells of the ovaries.
B. Receptors for kisspeptin will be found in the cytoplasm of cells in the hypothalamus.
C. High levels of estrogen would increase kisspeptin synthesis.
D. Low levels of estrogen would increase kisspeptin synthesis.

Answer 11

D. Low levels of estrogen would increase kisspeptin synthesis.

Question 12

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. People whose set point has increased eat more than they need and gain weight.

Permanently raising the set point would involve a permanent change in which of the answer choices?

A. the response
B. the sensor
C. the stimulus
D. the effector

Answer 12

B. the sensor
-The sensor would recognize the feeling of hunger, or a need for caloric intake. If the set point is raised to a higher number of daily calories, then the sensor would have to change so that it only responds (by decreasing hunger) when the higher caloric number is consumed.

Question 13

Low levels of iodine will cause an increase in the synthesis of which of the following? (Select all that apply)

• T3
  -TSH
• TRH
• T4
• Thyroglobulin

Answer 13

• TSH
• TRH
• Thyroglobuli

Question 14

Many birth control pills release a constant amount of synthetic estradiol and progesterone for 21 days, followed by 7 days during which no hormones are ingested. Which of the statements describes the effects of birth control pills?
A. Birth control pills inhibit the development of the uterine lining so that implantation of a fertilized oocyte cannot occur.
B. Birth control pills maintain constant levels of estrogens and/or progesterone so that they hypothalamus releases GnRH to stimulate LH secretion and ovulation does not occur.
C. Birth control pills maintain constant levels of estrogens and/or progesterone so that the hypothalamus decreases release of GnRH blocking a surge in LH and ovulation does not occur.
D. Birth control pills maintain constant levels of estrogens and/or progesterone so that the hypothalamus releases GnRH to stimulate FSH secretion and oocyte maturation

Answer 14

C. Birth control pills maintain constant levels of estrogens and/or progesterone so that the hypothalamus decreases release of GnRH blocking a surge in LH and ovulation does not occur.
- The ovarian cycle is regulated via negative feedback between the ovaries and the hypothalamus/anterior pituitary. Low levels of estrogen and progesterone stimulate the initiation of a new ovarian cycle and follicular development.

Question 15

Your core body temperature set point has just decreased. As a result you…

A. None of the other answer choices are correct
B. Feel cold and shiver
C. Feel cold and sweat
D. Feel hot and shiver
E. Feel hot and sweat

Answer 15

E. Feel hot and sweat

Question 16

When people have a few drinks containing alcohol, they often feel the need to urinate. This response suggests interplay between alcohol and antidiuretic hormone (ADH). ADH is released by the posterior pituitary and acts on target cells within the kidneys. Which of these statements could explain how alcohol and ADH interact?
A. Alcohol decreases the release of ADH.
B. Alcohol increases the release of ADH.
C. Alcohol facilitates the binding of ADH to receptors in the brain, so individuals “feel” the need to urinate
D. Alcohol inhibits the binding of ADH to receptors in the brain, so individuals “feel” the need to urinate.

Answer 16

A. Alcohol decreases the release of ADH.
- ADH acts on the kidneys to increase water uptake and reduces urination. Inhibiting this hormone results in more water exiting the kidneys into the collecting ducts and increasing urine production

Question 17

When a low frequency sound enters the cochlea, the stereocilia of hair cells closer to the base of the basilar membrane…
A. bend away from the kinocilium to close K+ channels that hyperpolarize the membrane, causing voltage-gated calcium channels to open
B. bend away from the kinocilium to cause the release of inhibitory neurotransmitters
C. bend toward the kiocilium to open K+ channels that depolarize the membrane causing voltage-gated calcium channels to open
D. bend toward the kinocilium to cause the release of excitatory neurotransmitters

Answer 17

A. bend away from the kinocilium to close K+ channels that hyperpolarize the membrane causing voltage-gated calcium channels to not open

Question 18

Which roles are played by sodium and calcium ions in coordinating the activation of a muscle by motor neurons? Select all that apply.

• sodium ions enter the motor endplate of the muscle fiber, causing depolarization of the muscle cells
• calcium ions are actively pumped into the sarcoplasmic reticulum to cause muscle relaxation by allowing tropomyosin to block actin binding sites
• calcium ions are released from the sarcoplasmic reticulum and bind with tropomyosin to open actin binding sites for myosin, leading to force generation
• calcium ions exit the motor neuron axon terminus to stimulate vesicle fusion and neurotransmitter release into the neuromuscular synapse
• calcium ions diffuse into the sarcoplasmic reticulum to open actin binding sites for myosin, leading to force generation

Answer 18

• sodium ions enter the motor endplate of the muscle fiber, causing depolarization of the muscle cells
• calcium ions are actively pumped into the sarcoplasmic reticulum to cause muscle relaxation by allowing tropomyosin to block actin binding sites

Question 19

Suppose the stereocilia of one hair cell become permanently bent away from the kinocilium. What will most likely happen as a consequence?
A. A single pitch will no longer be perceivable depending on the hair cell’s location
B. Many pitches will be constantly perceived
C. Many pitches will no longer be perceivable
D. A single pitch will be constantly perceived depending on the hair cell’s location

Answer 19

A. A single pitch will no longer be perceivable depending on the hair cell’s location

Question 20

You turn on a light so you can get a glass of water. AFTER you turn on the light, your bipolar cells are __________________.
A. hyperpolarized
B. none of the above
C. depolarized

Answer 20

C. depolarized

Question 21

What effect would an increase in the stiffness of the basilar membrane at the apex of the cochlea have on a person’s hearing?
A. The person would lose the ability to hear high-pitched sounds.
B. The person would lose the ability to hear low-pitched sounds
C. The person would not be able to distinguish the amplitude of a sound
D. The person would only be able to hear loud sounds.

Answer 21

B. The person would lose the ability to hear low-pitched sounds

Question 22

Glutamate is the neurotransmitter released at the rod-bipolar cell synapse. When there is no light, the rod membrane potential will ____________ due to _________ of cations through the channel.
A. hyperpolarize; exit
B. depolarize; entry
C. depolarize; exit
D. hyperpolarize; entry

Answer 22

B. depolarize; entry

Question 23

When compared to the leg muscles of an Olympic sprinter, the muscles of an Olympic marathoner would likely show a lower proportion of oxidative slow-twitch fibers: true or false.

Answer 23

false
-Oxidative slow-twitch fibers are important for repeated contraction in the muscle with limited fatigue. Slow-twitch muscle is characterized by higher density of myoglobin and mitochondria to fuel oxidative phosphorylation, which provides more ATP for repeated muscle contractions.

Question 24

You turn on a light so you can get a glass of water. At the moment the light turns ON, the relative amount of Gα-GDP of trimeric G proteins __________.

A. increases
B. does not change
C. decreases

Answer 24

C. decreases

Question 25

You measure levels of Ca2+ in various locations within a motor neuron and a skeletal muscle fiber when the motor neuron is depolarized, and the muscle fiber is actively shortening.

Where do you expect to find higher levels of Ca2+?
A. bound to myosin
B. in vesicles within the motor neuron
C. diffusing into the axon terminus of a motor neuron through specialized channels in the plasma membrane
D. bound to tropomyosin
E. within the sarcoplasmic reticulum
F. binding to the receptors at the motor endplate of the muscle cell
G. bound to troponin

Answer 25

G. bound to troponin
- When the muscle cell is depolarized, calcium leaves the sarcoplasmic reticulum and binds troponin. This results in tropomyosin revealing the myosin binding sites of actin filaments, thus allowing cross-bridge formation and muscle shortening.

Question 26

The ventricles finish filling with blood after the ____.
A. PR segment
B. ST segment
C. P wave
D. T wave
E. QRS complex

Answer 26

A. PR segment