Ap Bio anatomy exam multiple choice

52. Antidiuretic hormone (ADH) is important in maintaining homeostasis in mammals. ADH is released from the hypothalamus in response to high tissue osmolarity. In response to ADH, the collecting duct and distal tubule in the kidney become more permeable to water, which increases water reabsorption into the capillaries. The amount of hormone released is controlled by a negative feedback loop. Based on the model presented, which of the following statements expresses the proper relationship between osmolarity, ADH release, and urine production? (A) As tissue osmolarity rises, more ADH is released, causing less water to be excreted as urine. (B) As tissue osmolarity rises, less ADH is released, causing less water to be excreted as urine. (C) As tissue osmolarity rises, more ADH is released, causing more water to be excreted as urine. (D) As tissue osmolarity rises, less ADH is released, causing more water to be excreted as urine.

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

38. The bacterium Vibrio cholerae is harmless unless a lysogenic bacteriophage provides the gene coding for the cholera toxin, which converts the bacterium to the virulent form that causes cholera. Which of the following best explains how the gene encoding cholera toxin becomes part of the bacterial genome? (A) The bacteriophage inserts the toxin gene into the host cell DNA, and the gene is expressed with the rest of the host cell's genes. (B) The bacteriophage makes copies of the toxin gene and expresses the copies inside the bacteriophage. (C) The bacteriophage converts its toxin gene into mRNA, which is then translated by the host cell. (D) The bacteriophage transforms itself into a self-replicating protein that can survive inside the host cell.

(A) The bacteriophage inserts the toxin gene into the host cell DNA, and the gene is expressed with the rest of the host cell's genes.

57. 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) An increase in action potentials in the motor neuron and constant nerve pain (B) A decrease in action potentials in the muscle, causing muscle weakness and fatigue (C) A decrease in the opening of sodium-gated channels in the muscle, causing less sodium to be released from the muscle (D) An increase in the opening of sodium-gated channels in the motor neuron because of the accumulation of acetylcholine in the junction

(B) A decrease in action potentials in the muscle, causing muscle weakness and fatigue

33. The mechanism of action of many common medications involves interfering with the normal pathways that cells use to respond to hormone signals. Which of the following best describes a drug interaction that directly interferes with a signal transduction pathway? (A) A medication causes the cell to absorb more of a particular mineral, eventually poisoning the cell. (B) A medication enters the target cell and inhibits an enzyme that normally synthesizes a second messenger. (C) A medication enters the target cell's nucleus and acts as a mutagen. (D) A medication interrupts the transcription of ribosomal RNA genes.

(B) A medication enters the target cell and inhibits an enzyme that normally synthesizes a second messenger.

47. Previous experiments indicate that CDK5 is active only when attached to a protein called p35. Which of the following best predicts how p35 might play a role in regulating neuron function? (A) Elevated intracellular levels of p35 result in increased synaptic activity. (B) Degradation of p35 results in increased synaptic activity. (C) Reabsorption of p35 from the synaptic cleft results in increased synaptic activity. (D) Attachment of p35 to synaptic vesicles results in increased synaptic activity.

(B) Degradation of p35 results in increased synaptic activity.

48. Based on the model, which of the following best explains how regulation of neurotransmitter release might increase the range of responses to a stimulus in the nervous system? (A) In the absence of any stimulus, neurons can still release neurotransmitters. (B) Different neurons in the same neural network can release different amounts of neurotransmitter. (C) In the depolarization phase of an action potential, postsynaptic neurons can adjust the amount of neurotransmitter bound to receptors on their surface. (D) In the recovery phase following a stimulus, enzymes can be mobilized to degrade molecules present in the synaptic vesicles.

(B) Different neurons in the same neural network can release different amounts of neurotransmitter.

56. Which of the following causes the rapid change of membrane polarity during an action potential? (A) Diffusion of neurotransmitters such as acetylcholine (B) Diffusion of positively charged ions across the cell membrane (C) Release of electrons from inside the cell (D) Release of protons from inside the cell (E) Active transport of cations by the sodium- potassium pump

(B) Diffusion of positively charged ions across the cell membrane

27. Which of the following is the correct sequence of events in an action potential after stimulation of a neuron? (A) K+ moves in; Na+ moves out. (B) Na+ moves in; K+ moves out. (C) Na+ moves in; Ca++ moves out. (D) Na+ moves in; Cl- moves out. (E) K+ moves in; organic anions move out.

(B) Na+ moves in; K+ moves out.

46. Based on the model, which of the following describes the most likely mechanism by which CDK5 regulates neurotransmitter release? (A) CDK5 adds methyl groups to DNA, altering expression of genes required for synthesis of neurotransmitters. (B) CDK5 promotes the rearrangement of the lipid molecules of two bilayers into a single membrane. (C) CDK5 alters the activity of other proteins involved in the movement of synaptic vesicles to the plasma membrane. (D) CDK5 binds to gated ion channels in the postsynaptic membrane, resulting in diffusion of calcium ions.

(C) CDK5 alters the activity of other proteins involved in the movement of synaptic vesicles to the plasma membrane.

20. Which of the following led to the increased function of the invertebrate nervous system? (A) Development of an advanced cerebellum (B) Evolution of a ventral nerve cord, thus increasing the ability to move (C) Cephalization of the major sensory organs and the cerebrum (D) Specialization of the sympathetic and parasympathetic systems within the nervous system (E) Occurrence of highly developed olfactory lobes in the invertebrate brain

(C) Cephalization of the major sensory organs and the cerebrum

26. Which of the following immune system cells is most severely depleted by HIV/AIDS ? (A) Plasma B cells (B) Memory B cells (C) Helper T cells (D) Cytotoxic ("Killer") T cells (E) Memory T cells

(C) Helper T cells

39. 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) Residual blood thyroxine, from prior to thyroid gland removal, will bind to cells in the anterior pituitary, signaling more TSH secretion. (B) Thyroxine will remain bound to thyroxine receptors on various body cells, and these body cells will secrete additional hormones that stimulate the anterior pituitary to secrete TSH. (C) Thyroxine that was stored in the anterior pituitary prior to thyroid gland removal will signal more TSH secretion. (D) A decrease in thyroxine levels means a loss of inhibition to the hypothalamus and anterior pituitary, leading to increased TSH secretion.

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

H+ + HCO3- (arrow) H2O +CO2 7. The equation above shows one of the reversible reactions that occur in blood. After exercise, an athlete's blood pH has dropped below the normal level. How will normal blood pH be restored? (A) An increase in O2 concentration in the plasma will lead to an increase in H+ concentration. (B) An increase in temperature will lead to an increase in H+ concentration. (C) An increase in sweating will lead to a decrease in OH- and H+ concentration. (D) An increase in breathing rate will lead to a decrease in blood CO2 and H+ concentration.

(D) An increase in breathing rate will lead to a decrease in blood CO2 and H+ concentration.

** I DON'T THINK THIS IS RELATED TO THIS UNIT BUT IT'S HERE JUST IN CASE 34. Methicillin-resistant Staphylococcus aureus (MRSA) can be a serious threat to human health. There is evidence that S. aureus infections are common in hospitals and that MRSA have become resistant to other antibiotics besides methicillin. This suggests that the rapid evolution of resistance in the bacteria poses a serious public-health challenge. Which of the following best explains the ability of MRSA to evade existing drug therapies? (A) MRSA have very long generation times and very large population sizes. (B) MRSA develop new alleles by intentionally introducing specific mutations that will give them a selective advantage over other bacteria. (C) MRSA metabolize many drugs in their lysosomes and therefore evolve resistance at a high rate. (D) MRSA exchange genetic material with other antibiotic-resistant bacteria, which can spread resistance in the S. aureus population.

(D) MRSA exchange genetic material with other antibiotic-resistant bacteria, which can spread resistance in the S. aureus population.

33. When a stimulus is applied to a receptor in the skin, an action potential is propagated along a neuron to the brain, where another signal is sent back to the muscle for a response. Which of the following best describes what occurs when the action potential reaches a chemical synapse at the end of an axon? (A) The action potential jumps from one axon to the next connecting axon. (B) The action potential travels through the synapse to the next connecting dendrite. (C) The action potential jumps the synapse to the next connecting dendrite. (D) The action potential causes a release of neurotransmitters that travel across the synapse.

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

41. Which of the following parts of the vertebrate brain is most closely associated with motor (muscular) coordination? (A) The hypothalamus (B) The medulla oblongata (C) The pineal body (D) The thalamus (E) The cerebellum

(E) The cerebellum

37. Which of the following diagrams best represents hormone-activated gene expression? click link to see image: https://drive.google.com/drive/u/0/folders/1GpZCfw-_KQowK03RWogPmHaCaZD9y8H4 (#37)

A.

2016 41. Transmission of an action potential across a synapse involves the release of neurotransmitters by the presynaptic neuron. The arrival of the action potential triggers a rise in the calcium concentration in the synaptic terminal, and the change in concentration triggers a release of neurotransmitters into the synaptic cleft. 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?

a

40. Which of the following representations best shows a portion of an axon at rest (before or after an action potential)? link to image: https://drive.google.com/drive/u/0/folders/1GpZCfw-_KQowK03RWogPmHaCaZD9y8H4

a.

1990 100. Which substance allows a single muscle twitch after a brief electrical stimulation of the sciatic nerve? a. Ringer's solution b.EDTA c. Botulin d. Malathion e.Curare

a. Ringer's solution

https://drive.google.com/drive/u/0/folders/1GpZCfw-_KQowK03RWogPmHaCaZD9y8H4 46. Information is transmitted through the nervous system when one neuron signals another neuron. The structure of neurons enables transmission to proceed quickly and efficiently. Which of the following diagrams correctly identifies both the structure of neurons and the direction of information flow between neurons?

d.

College board practice 2 Antidiuretic hormone (ADH) is important in maintaining homeostasis in mammals. ADH is released from the hypothalamus in response to high tissue osmolarity. In response to ADH, the collecting duct and distal tubule in the kidney become more permeable to water, which increases water reabsorption into the capillaries. The amount of hormone released is controlled by a negative feedback loop. Based on the model presented, which of the following statements expresses the proper relationship between osmolarity, ADH release, and urine production? A) As tissue osmolarity rises, more ADH is released, causing less water to be excreted as urine. B) As tissue osmolarity rises, less ADH is released, causing less water to be excreted as urine. C) As tissue osmolarity rises, more ADH is released, causing more water to be excreted as urine. D) As tissue osmolarity rises, less ADH is released, causing more water to be excreted as urine.

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

(1990 19) Compounds that are foreign to an organism and that elicit an immune response in the organism are called A. antigens B. interferons C. teratogens D. antibodies E. histamines

A. antigens

College board 9 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? A) The activation of clotting factors will be blocked. B) The rate of fibrin formation will decrease. C) Thrombin will be converted to prothrombin. D) The rate of blood clot formation will increase.

B) The rate of fibrin formation will decrease.

college board 6 The endocrine system incorporates feedback mechanisms that maintain homeostasis. Which of the following demonstrates negative feedback by the endocrine system? a) During labor, the fetus exerts pressure on the uterine wall, inducing the production of oxytocin, which stimulates uterine wall contraction. The contractions cause the fetus to further push on the wall, increasing the production of oxytocin. B)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. C) At high elevation, atmospheric oxygen is more scarce. In response to signals that oxygen is low, the brain decreases an individual's rate of respiration to compensate for the difference. d) A transcription factor binds to the regulatory region of a gene, blocking the binding of another transcription factor required for expression.

B)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

1990 97. Which of the following substances allows action potentials to reach the sarcoplasmic membrane and the transverse tubule system but prevents muscle contraction? A. Ringer's solution B. EDTAC. BotulinD. Malathion E. Curare

B. EDTAC.

34. The diagram above depicts the response to a pinprick (stimulus) on the tip of a human finger. The arrows show the direction of impulse transmission along the labeled axons. If axon II was damaged before the pinprick, which of the following is most likely? (A) The person will not feel the pinprick. (B) The person can no longer feel pain. (C) The person's finger will not withdraw reflexively. (D) The person cannot transmit nerve impulses to the brain.

C) The person's finger will not withdraw reflexively.

College board 5 Vertebrate immune responses involve communication over short and long distances. Which of the following statements best helps explain how cell surface proteins, such as MHCMHC proteins and T cell receptors, mediate cell communication over short distances? A) The proteins receive electrical signals from nerve cells. B) The proteins leave the cell and travel in the bloodstream to other cells. C) The proteins interact directly with proteins on the surfaces of other cells. D) The proteins bind to molecules secreted by cells located in other parts of the body.

C) The proteins interact directly with proteins on the surfaces of other cells.

1990 99. Which substance produces a sustained contraction (tetany) after a brief electrical stimulation of the sciatic nerve? A. Ringer's solution B. EDTA C. Botulin D. Malathion E. Curare

D. Malathion

(1990 14) Which of the following is most often associated with the elaborate courtship rituals conducted by many birds? a. Species recognition b. Migration c. Feeding responses d. Altruism e. Kin selection

a. Species recognition

1990 98. Competitors of acetylcholine include which of the following? I. Botulin II. EDTA III. Curare A. I only b. II only c. III only d. I and II only e. I, II, and III

d. I and II only

1999 6. Which of the following types of behavior describes the way that mice find their way through mazes? a. habituation b. imprinting c. reasoning d. instinct e. trial and error

e. trial and error

39. An individual's humoral response to a particular antigen differs depending on whether or not the individual has been previously exposed to that antigen. Which of the following graphs properly represents the humoral immune response when an individual is exposed to the same antigen more than once? answer choices are images (A) (B) (C) (D)

(A)

2016 To test their model, the researchers used a modified version of green fluorescent protein (GFP*). In slightly alkaline conditions, GFP* exhibits a bright green fluorescence. In acidic conditions, GFP* exhibits no fluorescence. Using standard techniques, the gene encoding GFP* is easily introduced into living cells. By engineering the expression of GFP* in laboratory-cultured nerve cells, the researchers found that a bright green fluorescence was exhibited only when a presynaptic neuron was given a certain stimulus. 44. Which of the following best explains why GFP* might exhibit a bright green fluorescence in alkaline conditions but not in acidic conditions? (A) Addition of an H+ to GFP* at acidic pH changes the shape of the protein, preventing fluorescence. (B) CDK5 is a degrading enzyme that hydrolyzes GFP* at alkaline pH, preventing fluorescence. (C) An influx of protons into the axon terminal activates synthesis of new GFP* molecules, preventing fluorescence. (D) Packaging of GFP* into synaptic vesicles is triggered by a sudden drop in cytosolic pH, preventing fluorescence.

(A) Addition of an H+ to GFP* at acidic pH changes the shape of the protein, preventing fluorescence.

41. During the fall, a chipmunk experiences a sustained period of cold weather. The chipmunk's thyroid gland responds by secreting a greater quantity of thyroxin. Which of the following represents the most accurate pathway from the central nervous system (CNS) to the target cells? (A) CNS → hypothalamus → anterior pituitary → thyroid → thyroxin → target cells. (B) CNS → adrenal medulla → thyroid → thyroxin → target cells. (C) CNS → motor neurons → muscle cells → thyroxin → target cells. (D) CNS → posterior pituitary → oxytocin → thyroid → thyroxin → target cells. (E) CNS → pancreas → insulin → sugar into cells → target cells.

(A) CNS → hypothalamus → anterior pituitary → thyroid → thyroxin → target cells.

2016 18. 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? (A) Epinephrine binds to a cell-surface receptor; the activated receptor stimulates production of the second messenger, cAMP. (B) Epinephrine binds to a cell-surface receptor; the activated receptor catalyzes the conversion of glycogen to glucose. (C) Epinephrine diffuses through the plasma membrane; the hormone dimerizes in the cytosol. (D) Epinephrine is taken into the cell by endocytosis; glycogen is converted to glucose in the endocytotic vesicle.

(A) Epinephrine binds to a cell-surface receptor; the activated receptor stimulates production of the second messenger, cAMP.

36. The table below describes the action of two genes involved in the regulation of nervous system development in the nematode C. elegans. Gene A Gene B Observation Pattern 1 Inactive Inactive No neurons develop. Pattern 2 Inactive Active No neurons develop. Pattern 3 Active Inactive Greater-than-normal number of neurons develop. Pattern 4 Active Active Normal number of neurons develop. Which of the following claims is best supported by the data? *TO SEE ACTUAL CHART HERE'S THE LINK: https://drive.google.com/drive/u/0/folders/1GpZCfw-_KQowK03RWogPmHaCaZD9y8H4 (A) Gene A promotes neuron development; gene B promotes programmed cell death in neuronal precursors. (B) Gene A promotes programmed cell death in neuronal precursors; gene B promotes neuron development. (C) Gene B must be active before gene A can function. (D) Gene B must be inactive before gene A can function.

(A) Gene A promotes neuron development; gene B promotes programmed cell death in neuronal precursors.

31. The endocrine system incorporates feedback mechanisms that maintain homeostasis. Which of the following demonstrates negative feedback by the endocrine system? (A) During labor, the fetus exerts pressure on the uterine wall, inducing the production of oxytocin, which stimulates uterine wall contraction. The contractions cause the fetus to further push on the wall, increasing the production of oxytocin. (B) 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. (C) At high elevation, atmospheric oxygen is more scarce. In response to signals that oxygen is low, the brain decreases an individual's rate of respiration to compensate for the difference. (D) A transcription factor binds to the regulatory region of a gene, blocking the binding of another transcription factor required for expression.

(B) 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.

2016: Researchers investigating the regulation of neurotransmitter release from presynaptic neurons proposed a model (Figure 1) in which CDK5, a protein expressed in axon terminals, inhibits the movement of synaptic vesicles to the presynaptic membrane. To test their model, the researchers used a modified version of green fluorescent protein (GFP*). In slightly alkaline conditions, GFP* exhibits a bright green fluorescence. In acidic conditions, GFP* exhibits no fluorescence. Using standard techniques, the gene encoding GFP* is easily introduced into living cells. By engineering the expression of GFP* in laboratory-cultured nerve cells, the researchers found that a bright green fluorescence was exhibited only when a presynaptic neuron was given a certain stimulus. 43. Based on the model, which of the following best explains why a bright green fluorescence was observed following stimulation of a presynaptic neuron? (A) GFP* synthesis was activated when a gene taken up by the neuron was switched on. (B) GFP* stored in the cytoplasm of the neuron was packaged into synaptic vesicles. (C) GFP* contained in synaptic vesicles moved into the synaptic cleft by exocytosis. (D) GFP* present in the synaptic cleft was reabsorbed by endocytosis into the neuron.

(C) GFP* contained in synaptic vesicles moved into the synaptic cleft by exocytosis.

31. Which of the following statements most correctly represents the organization of living systems from smallest to largest? (A) Molecules → organs → cells → organisms (B) Cells → tissues → molecules → ecosystems → communities (C) Organisms → molecules → cells → atoms (D) Atoms → molecules → cells → organisms → ecosystems (E) Organs → plants → animals → cells

(D) Atoms → molecules → cells → organisms → ecosystems

45. Which of the following observations best supports the hypothesis that CDK5 negatively regulates neurotransmitter release? (A) Introduction of CDK5 protein into neurons results in the movement of synaptic vesicles to the plasma membrane in the absence of any stimulus. (B) Uptake of a gene encoding CDK5 by neurons results in the movement of synaptic vesicles to the plasma membrane in the absence of any stimulus. (C) Suppression of CDK5 expression in neurons inhibits the movement of synaptic vesicles to the plasma membrane in response to a specific stimulus. (D) Inhibition of CDK5 activity in neurons increases the movement of synaptic vesicles to the plasma membrane in response to a specific stimulus.

(D) Inhibition of CDK5 activity in neurons increases the movement of synaptic vesicles to the plasma membrane in response to a specific stimulus.

2016 28. Steroid hormones, such as testosterone, pass through the plasma membrane and bind to an intracellular protein, as shown in the diagram below. The hormone-receptor complex then enters the nucleus, where it interacts with DNA to promote transcription of a specific gene. Based on the information presented, which of the following will also occur in response to steroid signaling? (A) Histone protein synthesis will increase because histones maintain the DNA in an optimal conformation for chromosome assembly. (B) Ribosome production will increase because ribosomes are specific for the mRNA with which they bind during translation. (C) DNA replication will increase as a result of the binding of the hormone-receptor complex to the DNA. (D) Production of a specific mRNA will increase as a result of the binding of the hormone-receptor complex to the DNA.

(D) Production of a specific mRNA will increase as a result of the binding of the hormone-receptor complex to the DNA.

44. Which of the following occurs in response to a rise in the blood sugar level? (A) The gall bladder releases glucagon. (B) Glycogen is catabolized. (C) Alpha cells in the pancreas secrete glucagon. (D) Beta cells in the pancreas release amylase. (E) Beta cells in the pancreas release insulin.

(E) Beta cells in the pancreas release insulin.

15. Birds associating the bright colors of certain butterflies with an unpleasant taste is an example of (A) instinct (B) habituation (C) imprinting (D) insight learning (E) trial-and-error learning

(E) trial-and-error learning

14. 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? answer choices are images (A) (B) (C) (D)

(c)

College board 3 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? A) Activated platelets release chemicals that inhibit blood clot formation. B) Activated platelets release signaling molecules that inhibit cell division in damaged tissue. C) Activated platelets constrict the blood vessels, stopping blood flow. D) Activated platelets release chemicals that activate more platelets.

D) Activated platelets release chemicals that activate more platelets.

1994 40. If a stimulus on the receptor portion of a sensory neuron is above the threshold level, a further increase in the intensity of this stimulus will most likely cause a. frequency of impulse production to increase b. strength of the neuronal impulse to increase c. impulse to move faster d. neuron membrane to become less permeable to sodium e. neuron membrane to become more negatively polarized

a. frequency of impulse production to increase

25. The transmission of information from sensory neurons to interneurons typically involves the (A) exchange of electrons between specialized proteins embedded in the plasma membrane of the sensory neuron to the plasma membrane of the interneuron (B) release of chemical messengers into the space between the axon of the sensory neuron and the plasma membrane of the interneuron (C) transfer of a phosphate group from ATP in the sensory neuron to a protein substrate in the interneuron (D) flow of protons down an electrochemical gradient through a gated channel between the sensory neuron and the interneuron

b.

26. The brain coordinates the circulatory and respiratory systems of the human body. The control of breathing, for example, involves neural pathways among the structures represented in the figure above. 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? https://drive.google.com/drive/u/0/folders/1GpZCfw-_KQowK03RWogPmHaCaZD9y8H4 (A) In response to depleted blood CO2 levels, the pH sensors send signals directly to the rib muscles, resulting in an increase in the rate of CO2 uptake by the lungs and a decrease in CO2 utilization by the brain. (B) 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 . (C) In response to high blood pH, the pH sensors send a signal directly to the lungs, resulting in a slower rate of breathing, and the lungs send a signal back to the heart once CO2 availability has been restored. (D) In response to an increased rate of breathing, the rib muscles send a signal to the brain, which then sends a signal to the heart, resulting in a decrease in heart activity and slower flow of blood through the body.

b.

51. Trypsinogen is split by the enzyme enterokinase to form an activated molecule of the protease trypsin. Which of the following would confirm that the activation of trypsin is an example of how a positive feedback mechanism can amplify a biological process? (A) The activated trypsin enzyme can use enterokinase as a substrate. (B) The trypsin produced by the reaction is capable of splitting and activating additional trypsinogen molecules. (C) If levels of trypsin were to get too high, the trypsin molecules would inhibit the enzyme enterokinase. (D) Each mRNA molecule that codes for trypsinogen can be translated repeatedly to form many peptide molecules.

b.

https://drive.google.com/drive/u/0/folders/1GpZCfw-_KQowK03RWogPmHaCaZD9y8H4 48. 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) A falling glucagon level causes a rise in the insulin level, which maintains equal amounts of both hormones in the blood. (B) A high glucagon level causes a rise in the insulin level, which maintains high levels of both hormones in the blood. (C) 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. (D) A low glucose level causes the release of insulin, which stimulates the release of more glucose from tissues, which in turn increases the amount of insulin being released.

c.

see link - https://drive.google.com/drive/u/0/folders/1GpZCfw-_KQowK03RWogPmHaCaZD9y8H4 49. Based on the experimental results, which of the following describes the most likely defect in muscle cells of patients with type 2 diabetes? (A) Insulin receptor proteins do not reach the cell surface. (B) Insulin does not activate its receptor. (C) IRS-1 activation is reduced at high insulin concentrations. (D) GLUT4 blocks glucose from entering cells.

c.

1994 63. Which of the following would occur as a result of increased activity of the sympathetic nervous system? a. accelerated digestion b. decreased heart rate c. increased adrenalin secretion d. increased salivation e. decreased glucose release by liver

c. increased adrenalin secretion

27. Thyroxin is a hormone that increases metabolic activities within various tissue targets. Low levels of circulating thyroxin trigger the secretion of thyroid-stimulating hormone (TSH) from the anterior pituitary. TSH secretion then stimulates thyroxin production and release by the thyroid gland. The increased level of circulating thyroxin inhibits further secretion of TSH from the anterior pituitary. Based on the information provided, which of the following can most likely be concluded about the TSH-thyroxin loop? (A) A person taking thyroxin to supplement low thyroxin secretion will produce more TSH. (B) Increased thyroxin production would cause elevated ribosomal activity in the anterior pituitary. (C) The structure of the loop would lead to elevated thyroid and tissue activity due to positive feedback. (D) The feedback mechanism would maintain relatively constant levels of thyroxin throughout tissue targets.

d.

https://drive.google.com/drive/u/0/folders/1GpZCfw-_KQowK03RWogPmHaCaZD9y8H4 41. Precise regulation of specific hormone levels is required for optimal sperm production in mammals, as summarized in the figure above. Anabolic-androgenic steroids (AAS) are synthetic variants of testosterone that are sometimes abused by persons who desire to enhance their athletic performance or alter their physique. Assuming that AAS function in the same way as naturally occurring testosterone, it is most likely that long-term abuse of AAS would (A) stimulate FSH secretion (B) stimulate testosterone production (C) stimulate LH secretion (D) reduce sperm production

d.

1994 21. Ducklings and goslings begin to following and congregate around whatever animate and inanimate object is presented to them within a few hours after hatching. This type of behavior is called a. unlearned b. trial and error c. habituation d. imprinting e. insight

d. imprinting

1994 60. which of the following best describes the function of cholinesterase in neurotransmission a. it decomposes, providing a source of choline for muscular contraction b. it binds acetylcholine reception to the post synaptic membrane c. it blocks acetylcholine reception on the postsynaptic membrane d. it breaks down acetylcholine, preventing continual transmission e. it releases ATP from acetylcholine, providing energy for neurotransmission

d. it breaks down acetylcholine, preventing continual transmission

(1990 16) Which of the following would result if the sodium-potassium pump of a neuron were inoperative? a. The movement of chloride ions would produce an action potential b. An impulse would travel from the axon to the dendrites of the neuron c. The rate of transmission of the impulse would greatly increase d. The rate of ATP synthesis would increase. e. The action potential would not occur.

e. The action potential would not occur.