1) A necropsy (postmortem analysis) of a marine sea star
that died after it was mistakenly placed in fresh water would likely show that
it died because
A) it was stressed and needed more time to acclimate to
the new conditions.
B) it was so hyperosmotic to the fresh water that it
could not osmoregulate.
C) the sea star's kidneys could not handle the change in
ionic content presented by the fresh water.
D) its contractile vacuoles ruptured.
E) its cells dehydrated and lost the ability to metabolize.
Answer: B
2) Organisms categorized as osmoconformers are most
likely
A) found in freshwater lakes and streams.
B) marine.
C) amphibious.
D) found in arid terrestrial environments.
E) found in terrestrial environments with adequate
moisture.
Answer: B
3) The body fluids of an osmoconformer would be ________
with its ________ environment.
A) hyperosmotic; freshwater
B) isotonic; freshwater
C) hyperosmotic; saltwater
D) isoosmotic; saltwater
E) hypoosmotic; saltwater
Answer: D
4) Compared to the seawater around them, most marine
invertebrates are
A) hyperosmotic.
B) hypoosmotic.
C) isoosmotic.
D) hyperosmotic and isoosmotic.
E) hypoosmotic and isoosmotic.
Answer: C
5) The fluid with the highest osmolarity is
A) distilled water.
B) plasma in birds.
C) plasma in mammals.
D) seawater in a tidal pool.
E) estuarine water.
Answer: D
6) Birds that live in marine environments and thus lack
access to fresh drinking water
A) osmoregulate without using a transport epithelium for
this purpose.
B) drink seawater and secrete excess ions through their
kidneys only.
C) drink seawater and secrete excess ions mainly through
their nasal salt glands.
D) have plasma that is isoosmotic to ocean water.
E) obtain water by eating only osmoregulating prey.
Answer: C
7) Osmoconforming sharks take in water, as needed,
A) by migrating to freshwater rivers to drink fresh
water.
B) via osmosis, as their body cells are slightly
hyperosmotic to seawater.
C) via active transport of water across the cells on
their gills.
D) by water diffusion from seawater, which is
hyperosmotic to the fluids in their cells.
E) by selective transport of water molecules across the
wall of the gut.
Answer: B
8) A human who has no access to fresh water but is forced
to drink seawater instead
A) will thrive under such conditions, as long as he has
lived at the ocean most of his life.
B) will excrete more water molecules than taken in,
because of the high load of ion ingestion.
C) will develop structural changes in the kidneys to
accommodate the salt overload.
D) will find that drinking saltwater satiates his thirst.
E) will risk becoming overhydrated within 12 hours.
Answer: B
9) Many marine and freshwater bony fish achieve
osmoregulation via
A) loss of water through the gills.
B) gain of salt through the gills.
C) loss of water in the urine.
D) no drinking of water.
E) gain of water through food.
Answer: E
10) Unlike most bony fishes, sharks maintain body fluids
that are isoosmotic to seawater, so they are considered by many to be
osmoconformers. Nonetheless, these sharks osmoregulate at least partially by
A) using their gills and kidneys to rid themselves of sea
salts.
B) monitoring dehydration at the cellular level with
special gated aquaporins.
C) tolerating high urea concentrations that balance
internal salt concentrations to seawater osmolarity.
D) synthesizing trimethylamine oxide, a chemical that binds
and precipitates salts inside cells.
E) possessing a special adaptation that allows their
cells to operate at an extraordinarily high salt concentration.
Answer: C
11) The necropsy (postmortem analysis) of a freshwater
fish that died after being placed accidentally in saltwater would likely show
that
A) loss of water by osmosis from cells in vital organs
resulted in cell death and organ failure.
B) high amounts of salt had diffused into the fish's
cells, causing them to swell and lyse.
C) the kidneys were not able to keep up with the water
removal necessary in this hyperosmotic environment, creating an irrevocable
loss of homeostasis.
D) the gills became encrusted with salt, resulting in
inadequate gas exchange and a resulting asphyxiation.
E) brain cells lysed as a result of increased osmotic
pressure in this hyperosmotic environment, leading to death by loss of
autonomic function.
Answer: A
12) Urea is produced in the
A) liver from NH₃ and CO₂.
B) liver from glycogen.
C) kidneys from glucose.
D) kidneys from glycerol and fatty acids.
E) bladder from uric acid and H₂O.
Answer: A
13) Urea is
A) insoluble in water.
B) more toxic to human cells than ammonia.
C) the primary nitrogenous waste product of humans.
D) the primary nitrogenous waste product of most birds.
E) the primary nitrogenous waste product of most aquatic
invertebrates.
Answer: C
14) Which nitrogenous waste has the greatest number of
nitrogen atoms?
A) ammonia
B) ammonium ions
C) urea
D) uric acid
Answer: D
15) Ammonia is likely to be the primary nitrogenous waste
in living conditions that include
A) lots of fresh water flowing across the gills of a
fish.
B) lots of seawater, such as a bird living in a marine
environment.
C) lots of seawater, such as a marine mammal (e.g., a
polar bear).
D) a terrestrial environment, such as that supporting
crickets.
E) a moist system of burrows, such as those of naked mole
rats.
Answer: A
16) Among vertebrate animals, urea
A) is made in the kidneys and immediately excreted.
B) is added to the air in the lungs to be exhaled, along
with carbon dioxide.
C) is made in the liver by combining two ammonia
molecules with one carbon dioxide.
D) is made in the pancreas and added to the intestinal
contents, along with bile salts, for excretion.
E) is rarely the nitrogenous waste of choice.
Answer: C
17) The nitrogenous waste that requires the most energy
to produce is
A) ammonia.
B) ammonium.
C) urea.
D) uric acid.
Answer: D
18) Excessive formation of uric acid crystals in humans
leads to
A) a condition called diabetes, where excessive urine
formation occurs.
B) a condition of insatiable thirst and excessive urine
formation.
C) gout, a painful inflammatory disease that primarily
affects the joints.
D) the absence of urea in the urine.
E) osteoarthritis, an inevitable consequence of aging.
Answer: C
19) Ammonia
A) is soluble in water.
B) can be stored in the body as a precipitate.
C) has low toxicity relative to urea.
D) is metabolically more expensive to synthesize than
urea.
E) is the major nitrogenous waste excreted by insects.
Answer: A
20) The advantage of excreting nitrogenous wastes as urea
rather than as ammonia is that
A) urea can be exchanged for Na+.
B) urea is less toxic than ammonia.
C) urea requires more water for excretion than ammonia.
D) urea does not affect the osmolar gradient.
E) less nitrogen is removed from the body.
Answer: B
21) The primary nitrogenous waste excreted by birds is
A) ammonia.
B) nitrate.
C) nitrite.
D) urea.
E) uric acid.
Answer: E
22) Which nitrogenous waste requires hardly any water for
its excretion?
A) amino acids
B) urea
C) uric acid
D) ammonia
E) nitrogen gas
Answer: C
23) In animals, nitrogenous wastes are produced mostly
from the catabolism of
A) starch and cellulose.
B) triglycerides and steroids.
C) proteins and nucleic acids.
D) phospholipids and glycolipids.
E) fatty acids and glycerol.
Answer: C
24) Birds secrete uric acid as their nitrogenous waste
because uric acid
A) is readily soluble in water.
B) is metabolically less expensive to synthesize than
other excretory products.
C) requires little water for nitrogenous waste disposal,
thus reducing body mass.
D) excretion allows birds to live in desert environments.
Answer: C
25) Among the following choices, the most concentrated
urine is excreted by
A) frogs.
B) kangaroo rats.
C) humans.
D) desert tortoises.
E) birds.
Answer: B
26) Materials are returned to the blood from the filtrate
by which of the following processes?
A) filtration
B) ultrafiltration
C) selective reabsorption
D) secretion
E) active transport
Answer: C
27) Excretory structures known as protonephridia are
present in
A) flatworms.
B) earthworms.
C) insects.
D) vertebrates.
E) cnidarians.
Answer: A
28) Excretory organs known as Malpighian tubules are
present in
A) earthworms.
B) flatworms.
C) insects.
D) jellyfish.
E) sea stars.
Answer: C
29) The osmoregulatory/excretory system of a freshwater
flatworm is based on the operation of
A) protonephridia.
B) metanephridia.
C) Malpighian tubules.
D) nephrons.
E) ananephredia.
Answer: A
30) Freshwater flatworms form a urine that is typically
A) of high solute concentration, in order to conserve
body fluids.
B) of very low volume, in order to conserve body fluids.
C) of high solute concentration and very low volume, in
order to conserve body fluids.
D) of high solute concentration and of high volume,
matching their normal fluid uptake.
E) of low solute concentration and of high volume,
matching their normal fluid uptake.
Answer: E
31) The osmoregulatory process called secretion refers to
the
A) formation of filtrate at an excretory structure.
B) reabsorption of nutrients from a filtrate.
C) selective elimination of excess ions and toxins from
body fluids.
D) formation of an osmotic gradient along an excretory
structure.
E) expulsion of urine from the body.
Answer: C
32) The osmoregulatory/excretory system of an earthworm
is based on the operation of
A) protonephridia.
B) metanephridia.
C) Malpighian tubules.
D) nephrons.
E) ananephredia.
Answer: B
33) The osmoregulatory/excretory system of an insect is
based on the operation of
A) protonephridia.
B) metanephridia.
C) Malpighian tubules.
D) nephrons.
E) ananephredia.
Answer: C
34) Which of the following pairs of organisms excrete
nitrogenous wastes in the form of uric acid?
A) mice and birds
B) insects and birds
C) lions and horses
D) humans and frogs
E) fish and turtles
Answer: B
35) Choose a pair that correctly associates the mechanism
for osmoregulation or nitrogen removal with the appropriate animal.
A) metanephridiumflatworm
B) Malpighian tubulefrog
C) kidneyinsect
D) flame bulbsnake
E) direct cellular exchangemarine
invertebrate
Answer: E
36) An excretory system that is partly based on the
filtration of fluid under high hydrostatic pressure is the
A) flame bulb system of flatworms.
B) protonephridia of rotifers.
C) metanephridia of earthworms.
D) Malpighian tubules of insects.
E) kidneys of vertebrates.
Answer: E
37) The transfer of fluid from the glomerulus to Bowman's
capsule
A) results from active transport.
B) transfers large molecules as easily as small ones.
C) is very selective as to which subprotein-sized
molecules are transferred.
D) is mainly a consequence of blood pressure in the
capillaries of the glomerulus.
E) usually includes the transfer of red blood cells into
Bowman's capsule.
Answer: D
38) Within a normally functioning kidney, blood can be
found in
A) the vasa recta.
B) Bowman's capsule.
C) the loop of Henle.
D) the proximal tubule.
E) the collecting duct.
Answer: A
39) A person with alkalosis will likely excrete urine
that has abnormally high levels of
A) bicarbonate ions.
B) sodium ions.
C) glucose.
D) ammonia.
E) NaOH.
Answer: B
40) The filtrate in the renal pelvis enters directly from
A) the loop of Henle.
B) the collecting duct.
C) Bowman's capsule.
D) the proximal tubule.
E) the glomerulus.
Answer: B
41) Juxtamedullary nephrons can concentrate salt
effectively in the renal medulla because of their long
A) loops of Henle.
B) distal convoluted tubules.
C) Bowman's capsules.
D) proximal convoluted tubules.
E) glomeruli.
Answer: A
42) The filtrate in the proximal convoluted tubule of the
human does not normally include
A) ions.
B) glucose.
C) plasma proteins.
D) amino acids.
E) dissolved gasses.
Answer: C
43) Human urine is usually more acidic than most other
body fluids because
A) hydrogen ions are actively moved into the filtrate.
B) the sodium transporter exchanges one hydrogen ion for
each sodium ion.
C) excreted plasma proteins are nearly all acidic ions.
D) excreted amino acids are in abundance.
E) potassium and sodium exchange generates lots of
acidity.
Answer: A
44) The osmolarity of human urine
A) can be four times as great as normal osmolarity of
human plasma.
B) is always exactly equal to plasma osmolarity.
C) is always less than plasma osmolarity.
D) is always greater than plasma osmolarity.
E) is determined primarily by the concentration of
glucose.
Answer: A
45) A primary reason that the kidneys have one of the
highest metabolic rates of all body organs is that
A) it stores the body's excess fats.
B) it has membranes of varying permeability to water.
C) it operates an extensive set of active-transport ion
pumps.
D) it is the body's only means of shedding excess
nutrients.
E) it has an abundance of myogenic smooth muscle.
Answer: C
46) Low selectivity of solute movement is a
characteristic of
A) salt pumping to control osmolarity.
B) H+ pumping to control pH.
C) reabsorption mechanisms along the proximal tubule.
D) filtration from the glomerular capillaries.
E) secretion along the distal tubule.
Answer: D
47) If ATP production in a human kidney was suddenly
halted, urine production would
A) come to a complete halt.
B) decrease, and the urine would be hypoosmotic compared
to plasma.
C) increase, and the urine would be isoosmotic compared
to plasma.
D) increase, and the urine would be hyperosmotic compared
to plasma.
E) decrease, and the urine would be isoosmotic compared
to plasma.
Answer: C
48) Compared to wetland mammals, water conservation in
mammals of arid regions is enhanced by having more
A) juxtamedullary nephrons.
B) Bowman's capsules.
C) ureters.
D) podocytes.
E) urinary bladders.
Answer: A
49) Processing of filtrate in the proximal and distal
tubules
A) achieves the sorting of plasma proteins according to
size.
B) achieves the conversion of toxic ammonia to less toxic
urea.
C) maintains homeostasis of pH in body fluids.
D) regulates the speed of blood flow through the
nephrons.
E) reabsorbs urea to maintain osmotic balance.
Answer: C
50) In humans, the transport epithelial cells in the
ascending loop of Henle
A) are the largest epithelial cells in the body.
B) are not in contact with interstitial fluid.
C) have plasma membranes of low permeability to water.
D) have 50% of their cell mass made of smooth endoplasmic
reticulum.
E) are not affected by high levels of nitrogenous wastes.
Answer: C
51) The typical osmolarity of human blood is
A) 30 mosm/L.
B) 100 mosm/L.
C) 200 mosm/L.
D) 300 mosm/L.
E) 500 mosm/L.
Answer: D
52) Trauma to the human kidney could result in a urinary
filtrate containing an abnormally high level of
A) fatty acids.
B) glucose.
C) salts.
D) erythrocytes.
E) vitamins.
Answer: D
53) When stimulated by aldosterone, the reabsorption of
Na+ is increased along
A) the loop of Henle.
B) the collecting duct.
C) Bowman's capsule.
D) the proximal tubule.
E) the distal tubule.
Answer: E
54) Increased ADH secretion is likely after
A) drinking lots of pure water.
B) sweating-induced dehydration increases plasma
osmolarity.
C) ingestion of ethanol (drinking alcoholic drinks).
D) eating a small sugary snack.
E) blood pressure is abnormally high.
Answer: B
55) After blood flow is artificially reduced at one kidney,
you would expect that kidney to secrete more of the hormone known as
A) erythropoietin.
B) angiotensinogen.
C) renin.
D) antidiuretic hormone.
E) atrial natriuretic peptide.
Answer: C
56) After drinking alcoholic beverages, increased urine
excretion is the result of
A) increased aldosterone production.
B) increased blood pressure.
C) inhibited secretion of antidiuretic hormone (ADH).
D) increased reabsorption of water in the proximal
tubule.
E) the osmoregulator cells of the brain increasing their
activity.
Answer: C
57) Osmoregulatory adjustment via the
renin-angiotensin-aldosterone system can be triggered by
A) sleeping for one hour.
B) severe sweating on a hot day.
C) eating a bag of potato chips.
D) eating a pizza with olives and pepperoni.
E) drinking several glasses of water.
Answer: B
58) Antidiuretic hormone (ADH) functions at the cellular
level by
A) stimulating the reabsorption of glucose through
channel proteins.
B) triggering the synthesis of an enzyme that makes the
phospholipid bilayer more permeable to water.
C) causing membranes to include more phospholipids that
have unsaturated fatty acids.
D) causing an increase in the number of aquaporin
molecules of collecting duct cells.
E) decreasing the speed at which filtrate flows through
the nephron, leading to increased reabsorption of water.
Answer: D
59) ADH and RAAS work together in maintaining
osmoregulatory homeostasis through which of the following ways?
A) ADH regulates the osmolarity of the blood and RAAS
regulates the volume of the blood.
B) ADH regulates the osmolarity of the blood by altering
renal reabsorption of water, and RAAS maintains the osmolarity of the blood by
stimulating Na+ reabsorption.
C) ADH and RAAS work antagonistically; ADH stimulates
water reabsorption during dehydration and RAAS causes increased excretion of
water when it is in excess in body fluids.
D) both stimulate the adrenal gland to secrete
aldosterone, which increases both blood volume and pressure via its receptors
in the urinary bladder.
E) by combining at the receptor sites of proximal tubule
cells, where reabsorption of essential nutrients takes place.
Answer: B
60, Use the following structural formulas to identify the
following items
Which of the following is excreted readily by aquatic
animals because of its high solubility in the respiratory medium?
A) A
B) B
C) C
D) D
E) E
Answer: A
61. Use the following structural formulas to identify the
following items
Which of the following is synthesized by mammals, most
amphibians, sharks, and some bony fishes, and has lower toxicity than its
nitrogenous substrate?
A) A
B) B
C) C
D) D
E) E
Answer: B
62. Use the following structural formulas to identify the
following items
Which of the following is excreted as a paste by land
snails, insects, birds, and many reptiles, because of its solubility and
toxicity properties?
A) A
B) B
C) C
D) D
E) E
Answer: C
63) In a laboratory experiment with three groups of
students, one group drinks pure water, a second group drinks an equal amount of
beer, and a third group drinks an equal amount of concentrated salt solution,
all during the same time period. Their urine production is monitored for
several hours. Which groups are expected to have the greatest and least amounts
of urine, respectively?
A) Beer drinkers have the most; salt solution drinkers
have the least.
B) Salt solution drinkers have the most; water drinkers
have the least.
C) Water drinkers have the most; beer drinkers have the
least.
D) Beer drinkers have the most; water drinkers have the
least.
E) There will be no significant difference between these
groups.
Answer: A
64) Unlike an earthworm's metanephridia, a mammalian
nephron
A) is intimately associated with a capillary network.
B) forms urine by changing fluid composition inside a
tubule.
C) functions in both osmoregulation and excretion.
D) receives filtrate from blood instead of coelomic
fluid.
E) has a transport epithelium.
Answer: D
65) Which process in the nephron is least selective?
A) filtration
B) reabsorption
C) active transport
D) secretion
E) salt pumping by the loop of Henle
Answer: A
66) Which of the following animals generally has the
lowest volume of urine production?
A) a vampire bat
B) a salmon in fresh water
C) a marine bony fish
D) a freshwater bony fish
E) a shark inhabiting freshwater Lake Nicaragua
Answer: C
67) The high osmolarity of the renal medulla is
maintained by all of the following except
A) diffusion of salt from the thin segment of the
ascending limb of the loop of Henle.
B) active transport of salt from the upper region of the
ascending limb.
C) the spatial arrangement of juxtamedullary nephrons.
D) diffusion of urea from the collecting duct.
E) diffusion of salt from the descending limb of the loop
of Henle.
Answer: E
68) Natural selection should favor the highest proportion
of juxtamedullary nephrons in which of the following species?
A) a river otter
B) a mouse species living in a tropical rain forest
C) a mouse species living in a temperate broadleaf forest
D) a mouse species living in a desert
E) a beaver
Answer: D
69) African lungfish, which are often found in small
stagnant pools of fresh water, produce urea as a nitrogenous waste. What is the
advantage of this adaptation?
A) Urea takes less energy to synthesize than ammonia.
B) Small stagnant pools do not provide enough water to
dilute the toxic ammonia.
C) The highly toxic urea makes the pool uninhabitable to
potential competitors.
D) Urea forms an insoluble precipitate.
E) Urea makes lungfish tissue hypoosmotic to the pool.
Answer: B
