Deck 30: Maintaining Homeostasis

Question 1

You are a professor supervising first year medical students. One student is examining the adrenal gland of his cadaver. "Wow!" he exclaims, "This person must have had an endocrine problem. Their adrenal gland lacks any kind of duct connecting it to the bloodstream. The hormones could only have oozed out." How do you respond?

A) "Look carefully and you will see the nerves that transport the hormones into the bloodstream."
B) "Do you see signs of adrenal insufficiency, such as low fat stores or muscle degeneration?"
C) "That's normal. The hormones ooze out and diffuse into nearby capillaries, which is why endocrine glands are sometimes called 'ductless glands'."
D) "That makes their adrenal gland similar to an exocrine organ."

Answer 1

"That's normal. The hormones ooze out and diffuse into nearby capillaries, which is why endocrine glands are sometimes called 'ductless glands'."

Question 2

Women often receive synthetic oxytocin to induce childbirth or augment contractions. What is an important consideration about the use of synthetic oxytocin?

A) The synthetic form does not travel down motor neurons, so it is less effective than the natural form.
B) It is impossible to mimic its chemical structure, so it may act on other receptors and cause side effects.
C) It can be difficult to get the levels just right, so uterine contractions can be too strong.
D) If you fail to simultaneously provide synthetic G protein, the hormone is ineffective.

Answer 2

It can be difficult to get the levels just right, so uterine contractions can be too strong.

Question 3

What is a primary function of growth hormone?

A) lowers blood glucose level
B) inhibits loss of calcium from bone
C) stimulates bone growth
D) initiates stress response
E) raises blood glucose level

Answer 3

stimulates bone growth

Question 4

Lampreys completely lack parathyroid glands. Suggest why these glands may be important for other vertebrates, but not for jawless fish.

A) Because they are parasitic, lampreys get plenty of calcium from their hosts.
B) Living in the ocean, they are surrounded by large amounts of sodium, chloride, and magnesium ions.
C) Jawless fish employ a different system than other vertebrates to regulate blood sugar.
D) Since they have a cartilaginous skeleton but not true bone, they have less need to regulate calcium levels.

Question 5

Starving children in war-torn countries have stick-thin limbs, as their muscle proteins are being broken down and the resultant amino acids are being used by other cells for energy. What hormone(s) would you expect to be especially elevated in these children?

A) glucagon
B) glucocorticoids
C) aldosterone
D) prolactin
E) insulin

Question 6

What condition is not associated with diabetes?

A) reduced body cell sensitivity to insulin
B) lowered production of insulin by the pancreas
C) careful diet and exercise measures are required to balance blood sugar levels
D) defects in pituitary gland function
E) elevated levels of blood glucose

Question 7

What hormone regulates the metamorphosis of tadpoles into frogs?

A) cortisol
B) somatotropin
C) melatonin
D) estrogen
E) thyroid hormone

Question 8

What statement does NOT correctly describe hormones that can directly enter a cell?

A) Once these hormones enter a cell, they bind to a cytoplasmic receptor and travel as a complex to the nucleus, or they may bind to the receptor after entering the nucleus.
B) Water-soluble hormones can enter directly into cells because of their nonpolar makeup.
C) Steroid hormones dissolve poorly in the plasma and are transported to target cells via special protein carriers.
D) Steroid hormones can enter directly into cells because of their hydrophobic makeup.

Question 9

What statement does NOT correctly describe antidiuretic hormone?

A) ADH secretion is stimulated by high blood osmolarity.
B) It inhibits the synthesis of aquaporins.
C) It binds to membrane receptors of cells in the mammalian kidneys.
D) It ultimately acts to reabsorb more water.
E) Damage to the posterior pituitary will decrease the production of ADH.

Question 10

What is NOT a function of parathyroid hormone?

A) It increases calcium production in the liver.
B) It stimulates osteoclasts to dissolve CaPO₄ crystals in bone.
C) It increases calcium absorption across the intestine.
D) It increases reabsorption of Ca²⁺ in the kidney.

Question 11

What feature distinguishes all hormones from neurotransmitters?

A) Hormones travel via the blood to a target tissue, while neurotransmitters cross the synaptic cleft to a postsynaptic cell.
B) A hormone affects reproductive functions, while neurotransmitters control all other processes.
C) Hormones are steroids, while neurotransmitters are amino acids.
D) Hormones require large concentrations to have an effect, while neurotransmitters require only low concentrations.

Question 12

What is the difference between the endocrine system and the autonomic nervous system?

A) The axons of neurons of the endocrine system travel a shorter distance than those of the autonomic nervous system.
B) The endocrine system employs chemical signals only, while the autonomic nervous system involves a combination of electrical and chemical signals.
C) Norepinephrine is produced by the autonomic nervous system, while epinephrine is produced by the endocrine system.
D) The autonomic nervous system promotes "fight or flight" functions, while the endocrine system promotes "rest and digest" functions.

Question 13

If blood transports hormones throughout the body, how do they communicate with specific targets?

A) Axonal pathfinding mediates the delivery of hormones to their specific targets.
B) Special gateway valves in the blood vessels direct hormones to their target tissues.
C) Special carrier proteins "walk" along microtubule tracts to deliver the hormones to their targets.
D) Only target tissues have receptors that allow them to receive the signal.

Question 14

Why don't hormones build up in the body over time?

A) They are filtered out of the blood by lymph tissues.
B) Hormone synthesis is subject to positive feedback regulation.
C) They are deactivated or degraded by target cells after hormone-receptor binding.
D) They do, but target tissues become desensitized over time.
E) They are secreted from the body by exocrine glands.

Question 15

You are researching an "orphan disease" with no available treatment. Your lab develops a drug that mimics a lipophilic hormone thought to be lacking in the disease, and you are looking for a pharmaceutical company to partner with to run a clinical trial. Based on the reaction from each team, which would you choose to work with?

A) Company A: "What you've developed is wonderful, but we'll need to develop a delivery system to get the drug across the cell membrane."
B) Company C: "We're interested in developing this drug - it could really help people. Do you know which genes the hormone regulates?"
C) Company B: "Your new drug seems very promising. Do you know which G-protein coupled receptor it binds to?"

Question 16

You are an attending physician supervising a new resident. Together, you decide to treat a patient with a steroid drug. The resident administers the drug and watches the patient anxiously. "It's not working," he mutters. How do you respond?

A) "Let's grab a cup of coffee and then check again. Activating the G-protein coupled receptor and its downstream kinase cascade can take several minutes."
B) "Why don't you go on your rounds and come back? Steroid hormones need several hours to work, since they regulate gene expression. Transcription and translation take time."
C) "You're right, it doesn't seem to be working. Let's increase the dose, since we need to achieve high steroid levels in the blood."
D) "We forgot to administer the carrier protein to get the drug across the cell membrane. We can add that now."

Question 17

Your friend is concerned because although she has never been pregnant, her breasts are producing milk. When she went to the doctor, he sent her to the MRI lab for a brain scan. She was too embarrassed to ask the doctor why. What do you tell her?

A) "They were actually scanning your thyroid gland, not your brain. Are you getting enough iodine in your diet?"
B) "LH and FSH from the posterior pituitary stimulate milk production. The doctor wants to rule out excess levels of estrogen in the pituitary stalk."
C) "The MRI technician must have mixed up your patient records. He should have done a thoracic scan instead."
D) "Prolactin from the anterior pituitary stimulates milk production. The doctor probably wants to rule out a pituitary tumor."

Question 18

The residents of a small town are concerned about possible pollutants being released by a nearby chemical plant. The cause of their concern is the recent discovery of dozens of small tadpoles with legs in ponds near the chemical plant. What is a possible explanation for these legged tadpoles?

A) The chemical plant is releasing chemicals that are similar in structure to G proteins.
B) The chemical plant is releasing chemicals that are similar in structure to cyclic AMP.
C) The chemical plant is releasing chemicals that are similar in structure to aldosterone.
D) The chemical plant is releasing chemicals that are similar in structure to thyroid hormones.
E) The chemical plant is releasing chemicals that are similar in structure to steroid hormones.

Question 19

Beta-blockers are a class of drugs that target beta-adrenergic receptors, blocking the action of epinephrine and norepinephrine. These drugs are used to treat heart conditions, hypertension, glaucoma, and migraine headaches and are also used off-label to alleviate stage fright in performers. Since the beta-adrenergic receptor is a GPCR, what intracellular event is prevented by the use of a beta-blocker?

A) a protein kinase cascade, initiated by the receptor's intracellular kinase domain
B) release of an activated G protein subunit bound to GTP
C) transport of the receptor-hormone complex into the cell and the nucleus, where it would regulate transcription
D) a protein phosphatase cascade, initiated by the receptor's intracellular phosphatase domain

Question 20

About 180 liters of blood plasma is filtered into human nephrons per day and, of that amount, about 1.5-2 liters leaves the body as urine. Therefore, the percentage of plasma filtrate that leaves as urine each day is about _______.

A) 0.1-0.2 percent
B) 10-20 percent
C) 0.5-1.0 percent
D) 1-2 percent
E) 5-10 percent
F) 20-50 percent

Question 21

This molecule or ion never uses active transport as its motive force for reabsorption into blood capillaries in the kidney.

A) Na⁺ ions
B) glucose
C) amino acids
D) Cl^- ions
E) water
F) HCO₃^- ions

Question 22

You wish to determine which organs function to remove waste products from the hemolymph (blood) of an insect. You do so by injecting a suspension of particulate dye particles into the abdominal cavity of an anesthetized cricket. Where will you find these dye particles 45 minutes later, after you euthanize and dissect the cricket?

A) in the Malpighian tubules
B) in the antennal glands
C) in the nephridia
D) in the nephrons of the kidneys
E) in the urinary bladder
F) in the protonephridia

Question 23

What is the route a red blood cell would take to circulate through a kidney, starting from the aorta?

A) renal vein -> vasa recta -> afferent arteriole -> glomerulus -> efferent arteriole -> renal artery
B) renal artery -> afferent arteriole -> vasa recta -> efferent arteriole -> glomerulus -> renal vein
C) renal artery -> afferent arteriole -> glomerulus -> efferent arteriole -> vasa recta -> renal vein
D) renal artery -> glomerulus -> afferent arteriole -> efferent arteriole -> vasa recta -> renal vein
E) renal vein -> efferent arteriole -> glomerulus -> afferent arteriole -> vasa recta -> renal artery
F) renal artery -> vasa recta -> afferent arteriole -> efferent arteriole -> glomerulus -> renal vein
G) renal vein -> glomerulus -> efferent arteriole -> afferent arteriole -> vasa recta -> renal artery

Question 24

Claire lost the ability to completely empty her bladder following a stroke, and a nurse inserts a catheter into the open end of her urinary tract each day to remove the urine. Into what structure does the nurse insert the catheter?

A) renal pelvis
B) bladder
C) ureter
D) collecting duct
E) nephron
F) urethra

Question 25

Roger has dangerously high levels of glucose in his blood. Genetic and protein tests reveal that he has mutations in two genes and abnormal amounts or activity of the proteins encoded by those two genes. What would be the most likely match to Roger's protein profile?

A) A
B) B
C) C
D) D

Question 26

Margaret had an unusual viral infection that damaged her posterior pituitary. Ever since, she has been excreting a large volume of dilute urine. The doctor tells Margaret that she has the disorder known as ____________.

A) hypertension
B) anti-diuresis
C) atherosclerosis
D) diabetes insipidus
E) diabetes mellitus

Question 27

Each nephron of the kidney consists of a long tubule and associated small blood vessels. Blood cells and plasma proteins are too large to enter with the glomerular filtrate. What is the correct path for the filtrate to follow through the nephron in the production of urine?

A) Bowman's capsule $\rightarrow$ distal convoluted tubule $\rightarrow$ loop of Henle $\rightarrow$ proximal convoluted tubule $\rightarrow$ collecting duct
B) Bowman's capsule $\rightarrow$ proximal convoluted tubule $\rightarrow$ loop of Henle $\rightarrow$ distal convoluted tubule $\rightarrow$ collecting duct
C) Bowman's capsule $\rightarrow$ loop of Henle $\rightarrow$ proximal convoluted tubule $\rightarrow$ distal convoluted tubule $\rightarrow$ collecting duct
D) Bowman's capsule $\rightarrow$ collecting duct $\rightarrow$ proximal convoluted tubule $\rightarrow$ loop of Henle $\rightarrow$ distal convoluted tubule
E) collecting duct $\rightarrow$ proximal convoluted tubule $\rightarrow$ loop of Henle $\rightarrow$ distal convoluted tubule $\rightarrow$ Bowman's capsule

Question 28

Refer to the figure. What is the most likely concentration of the fluid in region E during moderate-volume urine production?

A) 5 mOsm
B) 300 mOsm
C) 700 mOsm
D) 1400 mOsm
E) 75 mOsm

Question 29

Connor decides to celebrate his 21^st birthday by drinking a few beers at a local sports bar. After a while, Connor notices that he is making many more trips to the men's room than the week before, when he drank similar amounts of carbonated water. Why is that?

A) Alcohol stimulates secretion of ions into the nephron and water follows by osmosis.
B) Alcohol stimulates filtration of the blood plasma by theglomeruli.
C) Alcohol inhibits reabsorption of sugars, amino acids and other small metabolites, which decreases reabsorption of water.
D) Alcohol inhibits the secretion of ADH by the posterior pituitary gland, thereby decreasing water reabsorption.
E) Alcohol stimulates the insertion of aquaporins into the plasma membranes of cells that line the collecting ducts, thereby decreasing water reabsorption.

Question 30

What cells directly stimulate the activity of other cells in the generation of an immune response?

A) monocytes
B) T cells
C) plasma cells
D) natural killer cells
E) B cells

Question 31

A patient with melanoma receives three types of therapy: surgery, radiation, and interferon. Which of these represents something the immune system uses against cancer as well?

A) Interferon -- cytotoxic T cells and natural killer cells insert interferon into the membranes of tumor cells, creating large pores that burst the cells.
B) Interferon -- T cells and natural killer cells secrete interferon in response to tumor cells
C) Interferon -- In complexes bound with MHC proteins, the interferons indicate the presence of altered tissue to B cells.
D) Radiation -- a class of lymphocytes uses powerful electromagnetic radiation to attack "altered self" cells

Question 32

What is a necessary component of a powerful immune system?

A) a large thyroid gland
B) thousands of different immunoglobulin genes
C) an ability to distinguish self from nonself
D) strict temperature homeostasis
E) different classes of plasma cells

Question 33

The human immunodeficiency virus mounts a direct attack on T_H cells by recognizing the _______ proteins in the plasma membrane of these cells.

A) CD8
B) CD4
C) Toll-like receptor
D) cytokine receptor
E) major histocompatibility class I

Question 34

The human immunodeficiency virus (HIV) cripples the functioning of the adaptive immune system because it selectively infects and destroys one particular class of cells, which are required for mounting a vigorous immune response to a variety of foreign pathogens or cancer cells. What cell is the most-likely target of the HIV virus?

A) suppressor T cells
B) cytotoxic T cells
C) helper T cells
D) natural killer cells
E) neutrophils

Question 35

MHC class II cell surface proteins are found on what cells?

A) neutrophils only
B) erythrocytes only
C) macrophages, B cells and dendritic cells
D) neutrophils and natural killer cells
E) natural killer cells only

Question 36

What do cytotoxic T cells interact with?

A) MHC class I proteins only
B) MHC class II proteins only
C) viral or cancer cell peptides only
D) MHC class I and MHC class II proteins
E) MHC class I proteins and viral or cancer cell peptides
F) MHC class II proteins and viral or cancer cell peptides

Question 37

Select the correct statement regarding the temperature response of the immune system.

A) Fever contributes to the body's defenses by stimulating the liver and spleen to store glucose.
B) Fever contributes to the body's defenses by stimulating the maturation of B cells into plasma cells.
C) After binding to a pathogen, macrophages release interleukin-1, which stimulates neurons in the hypothalamus to raise the body's temperature, producing a fever.
D) When neutrophils encounter invading cells, they release immunoglobulin-1, which is carried to the brain by the circulatory system.
E) Fevers between 99 $\degree$ and 100 $\degree$ F are often fatal.

Question 38

A friend tells you the following story. "My aunt just received a heart transplant. Her doctors warned us that her body might reject the tissue. I just can't understand how that could happen as human hearts are made of the same tissues, aren't they?" How do you respond?

A) "Yes, all human hearts are made of cardiac muscle. But, most people have different MHC class I proteins on their cell surfaces. Your aunt's immune system can cause tissue rejection because of the 'nonself' MHC proteins on the donor heart."
B) "Yes, all human hearts are made of cardiac muscle, so I am as perplexed as you are."
C) "Yes, all human hearts are made of cardiac muscle. As far as the rejection of tissues goes, your aunt might have different antibodies than did the donor, which could lead to a rejection."
D) "Yes, all human hearts are primarily made of cardiac musclec, except some humans have different tissues inside their hearts and this could lead to a tissue rejection by the recipient."
E) "Yes, all human hearts are made of cardiac muscles. However, your aunt might have been given some type of drug during the transplant operation that might cause tissue rejection. You can never be too careful in a hospital, you know."

Question 39

Which of the following cells is matched to an incorrect function?

A) plasma cells-secrete immunoglobulins
B) neutrophil-important antigen-presenting cell
C) natural killer cells-kill virus-infected and tumor cells
D) macrophage-phagocytic cell
E) monocyte-precursor of macrophage

Question 40

What is true regarding cytokines?

A) Cytokines protect in the attack of pathogens by phagocytosis.
B) Cytokines are secreted by pathogens during infection.
C) Cytokines are immune cells involved in producing antibodies.
D) Cytokines are secreted by T_H cells and bind to receptors.
E) Cytokines bind to intracellular receptors.

Question 41

A young child is extremely susceptible to infections by a wide range of bacteria. A genome sequencing test determines that the boy has an inactivating mutation in a single gene. What is the most-likely candidate for the mutated gene?

A) a major histocompatibility class I protein
B) an immunoglobulin
C) a Toll-like receptor
D) a CD8 protein
E) a type I interferon

Question 42

Until renamed by Paul Ehrlich in the 1890s, the heat-labile, nonspecific part of the immune system that enhances inflammation was known as "alexin". We now know that various proteins of this system have a variety of functions, including bursting pathogens by insertion of a membrane-attack complex. What did Erhlich rename this specific part of the innate immune system?

A) immunoglobulins
B) major histocompatibility proteins
C) mannose-binding lectins
D) the complement system
E) Toll-like receptors

Question 43

A patient has come to you for a second opinion. "I have these mysterious lumps in my right armpit," he says, "The other doctor says we may have to remove them. What do you think?" You notice red scratches on the patient's right arm. "You must have a new kitten. Cat scratch disease, from the bacterium Bartonella ," you say, "And we certainly won't remove those lumps, they are really important! Those are your..."

A) "spleen, where hematopoietic stem cells produce lymphoid and myeloid progenitors."
B) "lymph nodes, where T-cell receptor genes are rearranged as T cells mature."
C) "lymph nodes, where naive B and T cells encounter antigens and become activated."
D) "thymus glands, where naive B and T cells encounter antigens and become activated."

Question 44

T cells binding to MHC class I-peptide complexes are responsible for acceptance or rejection of transplanted organs. To facilitate acceptance of the transplant, the ideal donor will have a close genetic relationship with the recipient -- even then, immune suppression drugs are often necessary. In a strange variation of this phenomenon, the endangered Tasmanian devil of Australia suffers from a devastating disease in which tumorous tissue is transmitted from animal to animal. What is the likely explanation for the lack of rejection of this transmissable tumor?

A) Tumors are never targeted by T cells, unless they are caused by a viral infection.
B) Tasmanian devils lack an adaptive immune system.
C) Inbreeding in the small population has led to reduced genetic diversity and much-less variable MHC class I genes.
D) MHC class I genes are unique to humans. Without them, the T cells have no way to distinguish self and non-self.

Question 45

Some scientists are trying to develop a vaccine that would prevent cancer. What is an important consideration?

A) Since cancer cells have self-marking MHC molecules, they cannot be attacked by the immune system.
B) Antigen selection would be critical, due to danger of the body's immune system attacking its own healthy tissue.
C) The natural killer (NK) cells already perform this function, which cannot be enhanced.
D) It is not possible -- vaccines can only protect against viruses or bacteria.

Question 46

A pathogenic virus has a new mutation in one of the coat proteins, that just happens to resemble the structure of a normal human protein present in dendritic cells of the central nervous system. What do you predict may be an outcome of infection by this virus?

A) The adaptive immune system will not respond to the virus because the innate immune system will destroy it first.
B) There will be no adaptive immune response to the virus, since all self-reactive T lymphocytes are removed in the thymus.
C) The membrane attack complex will be unable to burst the viral membrane.
D) The body's immune system will start attacking the brain cells because the viral protein is very similar to the protein on the dendritic cells.

Question 47

You have a patient in your office who has the autoimmune disease systemic lupus erythematosus, which is being successfully treated using immunosuppressive drugs. Generally you recommend a yearly flu shot to your patients, which is available either in an injected, inactivated form or as a live, attenuated virus nasal spray. For this patient, what detail should you consider?

A) Since she has an autoimmune disease, the patient is likely to be allergic to chicken eggs, and should not get the vaccine.
B) You should wait about six weeks to vaccinate, until the lupus passes through the patient and she is well.
C) Having lupus demonstrates that the patient does not have a functional immune system, and therefore it would be pointless to vaccinate.
D) The injected, inactivated vaccine would be a better choice than the live attenuated nasal spray vaccine, since the patient is on immunosuppressive drugs.

Question 48

When developing a monoclonal antibody-based test kit, great care must be taken to choose an antibody with the right binding properties. Imagine that you are developing a food-testing kit to specifically detect E. coli 0157:H7, a pathogenic serotype of E. coli that causes food poisoning. Choose the hybridoma line best suited for use in your test kit.

A) 1
B) 2
C) 3
D) 4
E) 5

Question 49

Different viruses have different properties that affect how the immune system responds to them, and consequently how vaccines must be developed.

-Every year a new version of the flu vaccine is made using a mixture of strains. The strains are chosen based on surveillance and analysis by experts from the FDA, WHO, and CDC. For other diseases however, such as varicella (chickenpox), the same vaccine is used continually and repeated vaccinations are not necessary. What do you conclude is the important difference between the influenza virus and the varicella zoster virus with regards to vaccinations?

A) Influenza virus has a much higher mutation rate than varicella, leading to frequent antigen changes in the coat proteins and a corresponding deficit of memory cells.
B) Varicella is attacked by the innate immune system, while influenza is attacked by the acquired immune system.
C) Influenza virus is transmitted through aerosol droplets in the air, while varicella can be transmitted via skin secretions.
D) Macrophages and neutrophils can clear all varicella viruses from the body but are unable to do the same for the influenza virus.
E) Influenza envelope proteins are bound by IgM, while varicella envelope proteins are bound by IgG.

Question 50

What is a consequence of the fact that the chickenpox virus has a much lower mutation rate than the influenza virus?

A) A chickenpox infection generally gives immunity against a repeat infection, but people can catch the flu every year.
B) Chickenpox virus can reemerge decades later with the symptoms of shingles, while influenza is transient.
C) Chickenpox virus can "hide out" as latent virus in nerve cell bodies, but influenza cannot.
D) Chickenpox creates skin lesions, while influenza leads to body aches.

Question 51

In the old days, milkmaids were exposed to cowpox from milking the cows, and this fortuitously gave them some protection from smallpox. What was happening in the milkmaids?

A) They were receiving a dose of generic IgG from the sick cows.
B) They were effectively receiving a vaccination from a related virus.
C) They were heightening their overall immune response due to exposure to the cowpox and other cow parasites.
D) They had a stronger immune response from drinking the milk, which sent cow B cells circulating through their blood.

Question 52

The human immunodeficiency virus (HIV) is so named because it cripples the immune system by attacking and destroying helper T cells (T_H cells). What cell surface protein does the HIV virus most likely use to bind to and infect the T_H cells?

A) defensin
B) MHC class I proteins
C) CD4
D) Toll-like receptor
E) mannose-binding lectin protein
F) membrane-attack complex
G) CD8

Question 53

Adult giraffes can be up to 20 ft tall, and thus require special adaptations to maintain appropriate blood pressure. One adaptation is the rete mirabile, a group of blood vessels that form a web or net-like structure to slow blood flow.

-The giraffe, as the tallest living land animal, has several adaptations for its height. To prevent blood from pooling in the head when it bends down to drink, the jugular veins of a giraffe have multiple one-way valves. Furthermore, a web of arteries and veins in the neck called the rete mirabile ("wonderful net") slows the flow of blood into the brain. These specializations of the ______________________ act as mechanisms to maintain ______________________.

A) nervous system; homeothermy
B) nervous system; temperature homeostasis
C) circulatory system; blood pressure homeostasis
D) circulatory system; pH homeostasis

Question 54

Due to a mutation in a smooth muscle gene, the blood vessels in the skin of a certain strain of mouse become dilated when temperature falls below a certain point. Based on the likely outcome of this mutation, what precautions should the researchers take to maintain the health of their mice?

A) The mouse room should be maintained at a cooler than normal temperature.
B) The mouse room should be consistently maintained at a warm temperature.
C) The mice will have weak muscles, and should be provided with exercise wheels.
D) The mice will be susceptible to high blood pressure, and should not be provided with exercise wheels.

Question 55

A scout troop sets out on a backpacking trip. Soon, an unexpected storm gets them drenched, and the troop leaders discover that few boys have packed warm clothes. Several scouts start shivering uncontrollably, a sign of hypothermia. The leaders call off the trip and the group heads back to their cars. This shivering response was

A) an attempt to produce heat by creating friction with their clothing.
B) an attempt to produce heat by burning large amounts of ATP.
C) a maladaptive response that wastes energy.
D) a social signal that evolved to alert adults to take action.

Question 56

If an animal suffered damage to the temperature sensor in its brain, what would be the result?

A) The integrating center would not receive inputs to compare to the set point. Body temperature could rise or fall to dangerous levels.
B) Only the integumentary system is required to sense temperature changes. Body temperature would remain stable.
C) The animal would have to rely on shivering instead of vasoconstriction to maintain body heat.
D) The animal would fall back onto a more primitive ectothermic mode of regulation.

Question 57

You are an engineer at a power plant that creates large volumes of hot waste water, which disrupts the ecosystem of the river it drains into. Another part of the plant requires warm oil, and the plant uses large amounts of energy to heat it. Inspired by countercurrent exchange in whales, you save energy and benefit the environment by doing what?

A) running the oil pipes under the river after dumping in the hot waste water
B) running the oil pipes around the waste water pipes, to allow heat transfer from water to oil
C) running the waste water and oil through a single pipe
D) adding a sensor, integrating center and effectors to control temperature in both pipes

Question 58

Something is terribly wrong with Beth and Steve's newborn baby girl. A biopsy of her kidneys reveals that the kidney nephrons all have extremely short Loops of Henle. What will be the ultimate fate of the baby?

A) She may die because her kidneys cannot secrete K⁺ and H⁺ ions into the nephron tubule.
B) She may die because her kidneys cannot filter urea out of the blood.
C) She may die because her kidneys cannot reabsorb enough filtered water.
D) She may die because her kidneys cannot reabsorb all the filtered sugars and amino acids.
E) She will live because the kidneys of fish, amphibians and reptiles function perfectly well without any Loops of Henle.