Biology 1407 - Chapter 44

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

A

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.

B

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.

B

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.

C

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.

C

The functional units of kidneys are _____. A) neurons B) glomeruli C) ureters D) nephrons E) collecting ducts

D

The nitrogenous waste that requires the most energy to produce is... A) ammonia. B) ammonium. C) urea. D) uric acid.

D

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.

A

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.

A

An albatross spending its life hovering over the ocean provides an extreme example of _____, the process by which animals control solute concentrations and balance water gain and loss. A) osmoregulation B) hydration C) evaporation D) osmosis E) excretion

A

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.

A

Excretory structures known as protonephridia are present in A) flatworms. B) earthworms. C) insects. D) vertebrates. E) cnidarians.

A

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.

A

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.

A

In a marine environment, animals that are isoosmotic relative to their environment _____. A) experience no net water loss by osmosis B) experience significant water gain by osmosis C) experience significant water loss by osmosis D) must expend energy on the active transport of solutes from their bodies to the environment E) can only survive in terrestrial environments

A

In each nephron of the kidney, the glomerulus and Bowman's capsule _____. A) filter the blood and capture the filtrate B) reabsorb water into the blood C) break down harmful toxins and poisons D) reabsorb salts and nutrients E) refine and concentrate the urine for excretion

A

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.

A

The fluid that enters vertebrate nephrons is called the filtrate. What is the source of the filtrate? A) blood in capillaries B) urine C) lymphatic fluid D) cells of the kidney E) the loop of Henle

A

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.

A

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.

A

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.

A

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.

A

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

A

Why do freshwater fish excrete a large amount of very dilute urine? A) Because they live in a hypoosmotic solution, their cells take up excess water that must be excreted. B) Because they live in a hypoosmotic solution, their cells tend to accumulate a lot of solute that must be excreted. C) Because they live in a hyperosmotic solution, their cells take up an excess of water that must be excreted. D) Because they live in a hyperosmotic solution, their cells tend to accumulate a lot of solute that must be excreted. E) Because animals must live in an isoosmotic solution, they excrete solutes to make the concentration of solutes in the water equal to the concentration of solutes in their cells.

A

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.

A

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.

B

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.

B

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.

B

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.

B

Among the following choices, the most concentrated urine is excreted by A) frogs. B) kangaroo rats. C) humans. D) desert tortoises. E) birds.

B

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.

B

Many insects, birds, and other reptiles excrete nitrogenous wastes in the form of uric acid, which _____. A) is synthesized in the kidneys from ammonia and CO2 B) forms solids that are relatively insoluble and nontoxic C) readily decomposes on exposure to air D) is readily excreted through feathers and scales E) can be recycled and utilized as an additional energy source

B

Metanephridia are found in _____ and function in _____. A) insects ... excretion B) annelids ... excretion and osmoregulation C) bats ... osmoregulation D) earthworms ... excretion E) birds ... osmoregulation and excretion

B

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.

B

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.

B

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.

B

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.

B

The filtrate formed by the nephrons in the kidney is not urine. The filtrate is first refined and concentrated by the processes of _____, which form the urine that leaves the body. A) filtration and secretion B) reabsorption and secretion C) reabsorption and excretion D) filtration and reabsorption E) secretion and excretion

B

The osmoregulatory/excretory system of an earthworm is based on the operation of A) protonephridia. B) metanephridia. C) Malpighian tubules. D) nephrons. E) ananephredia.

B

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

B

Which excretory system contains structures called flame bulbs that function in filtration? A) metanephridia B) protonephridia C) Malpighian tubules D) kidneys E) nephrons

B

Which of the following is a tube that carries urine from the kidneys to the urinary bladder in a mammal? A) loop of Henle B) ureter C) urethra D) distal tubule E) proximal tubule

B

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

B

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.

C

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.

C

All of the following processes occur in the nephron of the kidney except _____. A) tubular secretion B) capsular filtration C) blood cell formation D) cellular respiration E) selective reabsorption

C

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.

C

At a particular position along a nephron, the osmotic potential of the filtrate is 500 mOsm/L whereas the surrounding kidney's is 600 mOsm/L. Which of the following is a likely result? A) Water will diffuse into the nephron by osmosis. B) Water will be pumped into the nephron by active transport. C) Water will diffuse out of the nephron by osmosis. D) Water will be pumped out of the nephron by active transport. E) There will be no net movement of water.

C

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.

C

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.

C

Compared to the seawater around them, most marine invertebrates are... A) hyperosmotic. B) hypoosmotic. C) isoosmotic. D) hyperosmotic and isoosmotic. E) hypoosmotic and isoosmotic.

C

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.

C

Excretory organs known as Malpighian tubules are present in A) earthworms. B) flatworms. C) insects. D) jellyfish. E) sea stars.

C

How do aquatic birds such as the wandering albatross avoid becoming dehydrated even though they live in an environment that is almost entirely salt water? A) They don't actually swallow the salt water. B) They excrete excess salt in their urine. C) They actively transport excess salt from the blood into secretory tubules found in special excretory glands. D) Like animals that live in extremely arid conditions, they are able to survive for long periods of time without fresh water, only drinking when they have access to fresh water on land or from rainwater. E) They are able to maintain their osmolarity close to that of seawater by maintaining salt, urea, and trimethyloxide levels in their body fluids, thus preventing the salt water from diffusing into their cells.

C

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.

C

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.

C

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.

C

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

C

Most aquatic animals excrete ammonia, whereas land animals excrete urea or uric acid. What is the most likely explanation for this difference? A) They have different diets. B) Land animals can get the energy needed to make urea or uric acid. C) Ammonia is very toxic, and it takes a lot of water to dilute it. D) Land animals cannot afford the energy needed to make ammonia. E) Fish need to get rid of ammonia, but land animals need it to live.

C

Most of our nitrogen-containing waste products are a result of _____. A) drug use B) consumption of foods high in nitrates, such as green vegetables C) protein metabolism D) the body's attempts to maintain pH homeostasis E) metabolism of fatty foods

C

Osmoconformers are animals that _____. A) expend considerable energy in matching concentrations of their body fluids with those of their marine environment. B) rely on the digestive, respiratory, and excretory systems to remove excess salts and water from their bodies C) have an internal environment isoosmotic with their external environment D) spontaneously absorb water through the body surface and lose solutes in urine E) spontaneously lose water through body surfaces and must actively unload ions and drink water to maintain osmotic homeostasis

C

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.

C

The bed of capillaries in a vertebrate kidney where water, urea, and salts are filtered out of the blood is the _____. A) Bowman's capsule B) collecting duct C) glomerulus D) loop of Henle E) proximal convoluted tubule

C

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.

C

The osmoregulatory/excretory system of an insect is based on the operation of A) protonephridia. B) metanephridia. C) Malpighian tubules. D) nephrons. E) ananephredia.

C

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.

C

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.

C

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

C

Which nitrogenous waste requires hardly any water for its excretion? A) amino acids B) urea C) uric acid D) ammonia E) nitrogen gas

C

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

C

Which of the following is the most accurate and comprehensive description of the function of kidneys? A) the breakdown of body wastes B) the excretion of wastes C) the regulation of body fluid composition D) filtration of the blood E) production of urine

C

Which type of organism would have the least chance of long-term survival in the given environment? A) osmoconformers in seawater B) euryhaline animals in fresh water C) stenohaline animals that move between fresh water and seawater D) osmoregulators in seawater E) euryhaline animals in seawater

C

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.

D

In our bodies, the primary nitrogen-containing compound excreted by our kidneys is _____. A) uric acid B) amino acids C) ammonia D) urea E) nitrite

D

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.

D

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

D

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

D

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.

D

The lowest osmotic potential inside a nephron will be found in _____. A) Bowman's capsule and the proximal tubule B) the descending limb of the loop of Henle C) the loop of Henle D) the thick segment of the ascending limb of the loop of Henle and the distal tubule E) the collecting duct

D

The most effective molecule for nitrogenous waste disposal in desert animals would be _____. A) ammonia because it uses less energy to make than uric acid or urea B) urea because it is less toxic than uric acid C) uric acid because it takes less energy to make than urea D) uric acid because it does not require water for excretion E) ammonia because it is the most soluble of all the nitrogen-containing metabolic waste products

D

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.

D

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.

D

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.

D

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.

D

What is the function of the ascending loop of Henle? A) It provides water for reabsorption by the interstitial fluid and capillaries. B) It loses urea to the renal medulla, helping this tissue to maintain its concentration gradient of solutes. C) It absorbs some drugs and poisons from surrounding capillaries. D) It helps maintain the concentration gradient of NaCl in the interstitial fluid, thus increasing water reabsorption. E) It collects processed filtrate from the nephrons.

D

Which is an accurate pairing of a key excretory function with its definition? A) Filtration happens when blood pressure forces water, nitrogenous waste, and valuable solutes from the blood into the collecting duct. B) Reabsorption is the reclamation process that returns valuable solutes and water to the nephron from the capillaries. C) Secretion transports certain toxins, drugs, and excessive ions from the filtrate to the capillaries. D) Excretion moves urine, the processed filtrate, out of the kidney, through the ureter, the bladder, and finally out of the body via the urethra. E) Reabsorption is the process in which toxins, drugs, and excessive ions that remain in the blood after filtration are transported into the nephron for disposal in the urine.

D

Which is an accurate statement about the anatomy of the human excretory system? A) Bowman's capsule is a network of capillaries inside the glomerulus. B) The proximal tubule is the portion of the nephron tubule farthest from Bowman's capsule. C) The renal cortex, which contains the nephrons, is interior to the renal medulla. D) The loop of Henle is located between the proximal tubule and the distal tubule. E) The distal tubule of a nephron connects with the renal pelvis of the kidney via the ureter.

D

Which nitrogenous waste has the greatest number of nitrogen atoms? A) ammonia B) ammonium ions C) urea D) uric acid

D

Which of the following is filtered from blood but not normally found in urine? A) water B) red blood cells C) H+ D) amino acids E) urea

D

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.

E

As filtrate passes through the long loop of Henle, salt is removed and concentrated in the interstitial fluid of the kidney medulla. Because of this high salt concentration, the nephron is able to _____. A) excrete the maximum amount of salt B) neutralize toxins that might accumulate in the kidney C) control the pH of the interstitial fluid D) excrete a large amount of water E) establish a hyperosmotic interstitial medullary concentration

E

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) kidney insect D) flame bulb snake E) direct cellular exchange marine invertebrate

E

Dehydration in animals _____. A) is always lethal B) that are exceptionally small, such as the tardigrade, is not usually fatal because of their large surface area-to-volume ratio C) is, on a cellular level, the opposite of freezing D) is a problem because fluid-mosaic cell membranes fall apart when deprived of water E) may be less damaging in the presence of sugar

E

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.

E

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.

E

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.

E

The primary nitrogenous waste excreted by birds is A) ammonia. B) nitrate. C) nitrite. D) urea. E) uric acid.

E

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.

E

Which of the following is a function of the excretory system? A) elimination of nitrogenous wastes B) maintenance of salt balance C) production of urine D) maintenance of the water balance E) All of the listed responses are correct.

E

Which of the following substances is generally filtered from the blood by the kidneys? A) water B) sodium C) urea D) glucose E) All of the listed responses are correct.

E