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Campbell Biology, 10e (Reece)
Chapter 44 Osmoregulation and Excretion
1) The force driving simple diffusion is _____, while the energy source for active transport is
_____.
A) the concentration gradient; ADP
B) the concentration gradient; ATP
C) transmembrane pumps; electron transport
D) phosphorylated protein carriers; ATP
2) To maintain homeostasis freshwater fish must _____.
A) excrete large quantities of electrolytes
B) consume large quantities of water
C) excrete large quantities of water
D) take in electrolytes through simple diffusion
3) Single-celled Paramecium live in pond water (a hypotonic environment). They have a
structural feature, a contractile vacuole, which enables them to osmoregulate. If you observed
them in the following solutions, at which sucrose concentration (in millimolars, mM) would you
expect the contractile vacuole to be most active?
A) 0.0 mM sucrose
B) 0.05 mM saline
C) 0.08 mM sucrose
D) 1.0 mM saline
4) Sharks live in seawater. Their tissues are isotonic to seawater, but their concentrations of
sodium ions, potassium ions, and chloride ions in cells and extracellular fluids are similar to
those of freshwater fishes. How is that possible?
A) Urea and trimethylamine oxide contribute to intra- and extracellular osmolarity in shark
tissues.
B) Metabolic intermediates of sharks tie up intracellular chloride and potassium ions.
C) Their blood is hypotonic to their tissues.
D) They excrete large quantities of electrolytes.
5) Hagfish (Eptatretus cirrhauts) are a jawless marine vertebrate that are isotonic with their
environment and are considered to be osmoconformers. How might this interesting adaptation
limit the habitat that the hagfish can tolerate?
A) Hagfish are not limited by salinity.
B) Osmoconformers do not face the same pressures as osmoregulators and can live in any marine
environment.
C) Individual hagfish will adapt to different salinities over their lifetime and, therefore, can
inhabit any marine environment.
D) Hagfish habitat is limited by the salinity of the environment.
6) Tissues of sharks are isotonic to seawater, but their concentrations of sodium ions, potassium
ions, and chloride ions in cells and extracellular fluids are similar to those of freshwater fishes.
What can you infer about the movement of sodium and chloride in these animals?
A) To maintain homeostasis of sodium and chloride levels, the shark must take up additional
sodium and chloride from seawater.
B) Sodium and chloride will diffuse into shark gills from seawater down their concentration
gradient.
C) Sharks conserve sodium and chloride, limiting excretion.
D) Sodium and chloride must be eliminated through the gills.
7) What role do chloride cells play in osmoregulation of marine fish with bony skeletons?
A) They actively transport chloride into the gills.
B) They mediate the movement of salt from seawater through their gills.
C) They are involved in excretion of excess salt.
D) They actively transport salt across the basolateral membrane of the rectal gland.
8) Salmon eggs hatch in freshwater. The fish then migrate to the ocean (a hypertonic solution)
and, after several years of feeding and growing, return to freshwater to breed. How can these
organisms make the transition from freshwater to ocean water and back to freshwater?
A) The rectal gland functions in the ocean water, and chloride cells function in freshwater.
B) Different gill cells are involved in osmoregulation in freshwater than in salt water.
C) Salmon in freshwater excrete dilute urine, and salmon in salt water secrete concentrated urine.
D) Their metabolism changes in salt water to degrade electrolytes.
9) Terrestrial organisms lose water through evaporation. In what ecosystem might an
entomologist find a good study organism to examine the prevention of water loss?
A) wet rain forest
B) desert
C) prairie
D) chaparral
10) 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 hypertonic to the fresh water that it could not osmoregulate
C) its contractile vacuoles ruptured
D) its cells dehydrated and lost the ability to metabolize
11) The body fluids of an osmoconformer would be _____ with its _____ environment
A) isoosmotic; freshwater
B) hyperosmotic; saltwater
C) isoosmotic; saltwater
D) hypoosmotic; saltwater
12) Compared to the seawater around them, most marine invertebrates are _____.
A) hyperosmotic
B) hypoosmotic
C) isoosmotic
D) hyperosmotic and isoosmotic
13) The fluid with the highest osmolarity is _____.
A) distilled water
B) plasma in birds
C) plasma in mammals
D) seawater in a tidal pool
14) A human who has no access to fresh water but is forced to drink seawater instead will _____.
A) thrive under such conditions, as long as he has lived at the ocean most of his life
B) excrete more water molecules than taken in, because of the high load of ion ingestion
C) develop structural changes in the kidneys to accommodate the salt overload
D) risk becoming overhydrated within twelve hours
15) 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 are balanced with internal salt concentrations to
seawater osmolarity
D) synthesizing trimethylamine oxide, a chemical that binds and precipitates salts inside cells
16) 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
17) 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 shark inhabiting the Mississippi River
18) One of the waste products that accumulates during cellular functions is carbon dioxide. It is
removed via the respiratory system. What is another waste product that accumulates during
normal physiological functions in vertebrates?
I) ammonia
II) uric acid
III) urea
A) only I and III
B) only II and III
C) only I and II
D) I, II, and III
19) Urea is produced in the _____.
A) liver from NH3 and carbon dioxide
B) liver from glycogen
C) kidneys from glycerol and fatty acids
D) bladder from uric acid and water
20) Urea is _____.
A) insoluble in water
B) the primary nitrogenous waste product of humans
C) the primary nitrogenous waste product of most birds
D) the primary nitrogenous waste product of most aquatic invertebrates
21) Which nitrogenous waste has the greatest number of nitrogen atoms?
A) ammonia
B) ammonium ions
C) urea
D) uric acid
22) 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) a terrestrial environment, such as that supporting crickets
D) a moist system of burrows, such as those of naked mole rats
23) 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) osteoarthritis, an inevitable consequence of aging
24) Ammonia _____.
A) is soluble in water
B) has low toxicity relative to urea
C) is metabolically more expensive to synthesize than urea
D) is the major nitrogenous waste excreted by insects
25) 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 does not affect the osmolar gradient
D) less nitrogen is removed from the body
26) 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
27) 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) can be reused by birds as a protein source
28) Among the following choices, the most concentrated urine is excreted by _____.
A) frogs
B) kangaroo rats
C) humans
D) freshwater bass
29) 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 makes lungfish tissue hypoosmotic to the pool.
30) Which of the following most accurately describes selective permeability?
A) An input of energy is required for transport.
B) Lipid-soluble molecules pass through a membrane.
C) There must be a concentration gradient for molecules to pass through a membrane.
D) Only certain molecules can cross a cell membrane.
31) Through studies of insect Malpighian tubules, researchers found that K+ accumulated on the
inner face of the tubule, against its concentration gradient. What can you infer about the
mechanism of transport?
A) Potassium transport is a passive process.
B) Movement of potassium into the lumen of the Malpighian tubules is an energy-requiring
process.
C) Potassium moves out of the tubules at a faster rate than it moves into the lumen of the tubules.
32) A potassium ion gradient is set up in insect Malpighian tubules through an active transport
process. As a result, potassium concentration is higher in the lumen of the tubules than in
hemolymph. How would the potassium gradient affect water movement?
A) Water would be forced out of the lumen of the Malpighian tubules through an osmotic
gradient.
B) The potassium gradient would have no effect on water movement.
C) There would be a net movement of water into the lumen of the tubules.
D) Water would be conserved, forming a hypertonic solution in the Malpighian tubules.
33) Why are the renal artery and vein critical to the process of osmoregulation in vertebrates?
A) The kidneys require constant and abnormally high oxygen supply to function.
B) The renal artery delivers blood with nitrogenous waste to the kidney and the renal vein brings
blood with less nitrogenous wastes away from the kidneys.
C) The kidneys require higher than normal levels of hormones.
D) The renal artery and vein are the main pathways regulating how much is produced by the
kidneys.
34) The figure above shows a nephron. Filtration takes place in the structure labeled _____.
A) a
B) b
C) c
D) d
35) The osmoregulatory/excretory system of a freshwater flatworm is based on the operation of
_____.
A) protonephridia
B) metanephridia
C) Malpighian tubules
D) nephrons
36) Materials are returned to the blood from the filtrate by which of the following processes?
A) filtration
B) selective reabsorption
C) secretion
D) excretion
37) Excretory organs known as Malpighian tubules are present in _____.
A) flatworms
B) insects
C) jellyfish
D) sea stars
38) The osmoregulatory process called secretion refers to the _____.
A) reabsorption of nutrients from a filtrate
B) selective elimination of excess ions and toxins from body fluids
C) formation of an osmotic gradient along an excretory structure
D) expulsion of urine from the body
39) The osmoregulatory/excretory system of an earthworm is based on the operation of _____.
A) protonephridia
B) metanephridia
C) Malpighian tubules
D) nephrons
40) Choose a pair that correctly associates the mechanism for osmoregulation or nitrogen
removal with the appropriate animal.
A) metanephridium — flatworm
B) Malpighian tubule — frog
C) flame bulb — snake
D) exchange across the body surface — marine invertebrate
41) 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) Malpighian tubules of insects
D) kidneys of vertebrates
42) 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
43) Within a normally functioning kidney, blood can be found in _____.
A) the vasa recta
B) Bowman's capsule
C) the proximal tubule
D) the collecting duct
44) A primary reason that the kidneys have one of the highest metabolic rates of all body organs
is that _____.
A) they have membranes of varying permeability to water
B) they operate an extensive set of active-transport ion pumps
C) they are the body's only means of shedding excess nutrients
D) they have an abundance of myogenic smooth muscle
45) Which process in the nephron is LEAST selective?
A) filtration
B) reabsorption
C) active transport
D) secretion
46) What is the function of the osmotic gradient found in the kidney? The osmotic gradient
allows for _____.
A) electrolytes to move from low to high concentrations in the absence of ATP
B) the precise control of the retention of water and electrolytes
C) the loop of Henle to deliver water to the renal vein
D) the filtration of large cells at the glomerulus
47) The loop of Henle dips into the renal cortex. This is an important feature of osmoregulation
in terrestrial vertebrates because _____.
A) absorptive processes taking place in the loop of Henle are hormonally regulated
B) differential permeabilities of ascending and descending limbs of the loop of Henle are
important in establishing an osmotic gradient
C) the loop of Henle plays an important role in detoxification
D) additional filtration takes place along the loop of Henle
48) Low selectivity of solute movement is a characteristic of _____.
A) H+ pumping to control pH
B) reabsorption mechanisms along the proximal tubule
C) filtration from the glomerular capillaries
D) secretion along the distal tubule
49) If ATP production in a human kidney was suddenly halted, urine production would _____.
A) decrease, and the urine would be hypoosmotic compared to plasma
B) increase, and the urine would be isoosmotic compared to plasma
C) increase, and the urine would be hyperosmotic compared to plasma
D) decrease, and the urine would be isoosmotic compared to plasma
50) Compared to wetland mammals, water conservation in mammals of arid regions is enhanced
by having more _____.
A) juxtamedullary nephrons
B) urinary bladders
C) ureters
D) podocytes
51) Processing of filtrate in the proximal and distal tubules _____.
A) achieves the conversion of toxic ammonia to less toxic urea
B) maintains homeostasis of pH in body fluids
C) regulates the speed of blood flow through the nephrons
D) reabsorbs urea to maintain osmotic balance
52) 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) are not affected by high levels of nitrogenous wastes
53) The high osmolarity of the renal medulla is maintained by all of the following EXCEPT
_____.
A) active transport of salt from the upper region of the ascending limb
B) the spatial arrangement of juxtamedullary nephrons
C) diffusion of urea from the collecting duct
D) diffusion of salt from the descending limb of the loop of Henle
54) 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
55) If you are hiking through the desert for several days, one would pack which of the following
to ensure proper hydration?
A) a drink with a combination of water and electrolytes
B) caffeinated beverages
C) bottled water kept at room temperature
D) bottled water that had been frozen to ensure that it would be as cold as possible
56) Increased antidiuretic hormone (ADH) secretion is likely after _____.
A) drinking lots of pure water
B) sweating-induced dehydration increases plasma osmolarity
C) eating a small sugary snack
D) blood pressure becomes abnormally high
57) After blood flow is artificially reduced at one kidney, you would expect that kidney to
secrete more of the hormone known as _____.
A) angiotensinogen
B) renin
C) antidiuretic hormone
D) atrial natriuretic peptide
58) 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
59) 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 pizza with olives and pepperoni
D) drinking several glasses of water
60) Antidiuretic hormone (ADH) and the renin-angiotensin-aldosterone system (the RAAS)
work together in maintaining osmoregulatory homeostasis through which of the following ways?
A) ADH regulates the osmolarity of the blood by altering renal reabsorption of water, and the
RAAS maintains the osmolarity of the blood by stimulating Na+ and water reabsorption.
B) ADH and the RAAS work antagonistically; ADH stimulates water reabsorption during
dehydration and the RAAS causes increased excretion of water when it is in excess in body
fluids.
C) Both stimulate the adrenal gland to secrete aldosterone, which increases both blood volume
and pressure via its receptors in the urinary bladder.
D) ADH and the RAAS combine at the receptor sites of proximal tubule cells, where
reabsorption of essential nutrients takes place.
