Chapter 44 (MC)

Which of the following is true of ammonia? A) It is soluble in water. B) It can be stored as a precipitate. C) It has low toxicity relative to urea. D) It is metabolically more expensive to synthesize than urea. E) It is the major nitrogenous waste excreted by insects.

A) It is soluble in water.

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) filtration

Which group possess excretory structures known as protonephridia? A) flatworms B) earthworms C) insects D) vertebrates E) cnidarians

A) flatworms

Which one of the following is extremely important for water conservation in mammals? A) juxtamedullary nephrons B) Bowmanʹs capsule C) urethra D) podocytes E) ureter

A) juxtamedullary nephrons

Where and from what compound(s) is urea produced? 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) liver from NH3 and CO2

Which structure descends deep into the renal medulla only in juxtamedullary nephrons? A) loop of Henle B) collecting duct C) Bowmanʹs capsule D) proximal convoluted tubule E) glomerulus

A) loop of Henle

Which of the following would contain blood in a normally functioning nephron? A) vasa recta B) Bowmanʹs capsule C) loop of Henle D) proximal tubule E) collecting duct

A) vasa recta

How do ADH and RAAS work together in maintaining osmoregulatory homeostasis? A) ADH monitors osmolarity of the blood and RAAS regulates blood volume. B) ADH monitors appropriate osmolarity by reabsorption of water, and RAAS maintains osmolarity by stimulating Na+ reabsorption. C) ADH an RAAS work antagonistically; ADH stimulates water reabsorption during dehydration and RAAS removal 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. E) Only when they are together in the receptor sites of proximal tubule cells, will reabsorption of essential nutrients back into the blood take place.

B) ADH monitors appropriate osmolarity by reabsorption of water, and RAAS maintains osmolarity by stimulating Na+ reabsorption.

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) Small stagnant pools do not provide enough water to dilute the toxic ammonia.

A marine sea star was mistakenly placed in freshwater and it died. What is the most likely explanation for its death? A) The sea star was stressed and needed more time to acclimate to new conditions. B) The sea star is hyperosmotic to the freshwater, and it could not osmoregulate. C) The osmoregulatory system of the sea star could not handle the change in ionic content presented by the freshwater. D) The contractile vacuoles used to regulate water content ruptured in the freshwater. E) The cells of the sea star dehydrated and lost the ability to metabolize.

B) The sea star is hyperosmotic to the freshwater, and it could not osmoregulate.

Which structure passes urine to the renal pelvis? A) loop of Henle B) collecting duct C) Bowmanʹs capsule D) proximal tubule E) glomerulus

B) collecting duct

The most concentrated urine is excreted by A) frogs. B) kangaroo rats. C) humans. D) desert tortoises. E) birds.

B) kangaroo rats.

Organisms categorized as osmoconformers are most likely A) found in fresh water lakes and streams. B) marine. C) amphibious. D) found in arid terrestrial environments. E) found in terrestrial environments with adequate moisture.

B) marine.

Which of the following is not a normal response to increased blood osmolarity in humans? A) increased permeability of the collecting duct to water B) production of more dilute urine C) release of ADH by the pituitary gland D) increased thirst E) reduced urine production

B) production of more dilute urine

Which of the following activities would initiate an osmoregulatory adjustment brought about primarily through the renin-angiotensin-aldosterone system? A) sleeping B) spending several hours mowing the lawn 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) spending several hours mowing the lawn on a hot day

The advantage of excreting 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) urea is less toxic than ammonia.

Proper functioning of the human kidney requires considerable active transport of sodium in the kidney tubules. If these active transport mechanisms were to stop completely, how would urine production be affected? A) No urine would be produced. B) A less-than-normal volume of hypoosmotic urine would be produced. C) A greater-than-normal volume of isoosmotic urine would be produced. D) A greater-than-normal volume of hyperosmotic urine would be produced. E) A less-than-normal volume of isoosmotic urine would be produced.

C) A greater-than-normal volume of isoosmotic urine would be produced.

A freshwater fish was accidentally placed in salt water. After several minutes in this saline water, it died. What is the most logical explanation for its death? A) Loss of water by osmosis in cells in vital organs resulting in cell death and eventually organ failure. B) Salt diffused into all the fishʹs cells causing them to swell and, in some cases, 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; death by loss of autonomic function.

C) The kidneys were not able to keep up with the water removal necessary in this hyperosmotic environment creating an irrevocable loss of homeostasis.

What is unique about transport epithelial cells in the ascending loop of Henle in humans? A) They are the largest epithelial cells in the body. B) They are not in contact with interstitial fluid. C) Their membranes are impermeable to water. D) 50% of their cell mass is comprised of smooth endoplasmic reticulum. E) They are not affected by high levels of nitrogenous wastes.

C) Their membranes are impermeable to water.

Which of the following animals generally has the lowest volume of urine production? A) a marine shark B) a salmon in freshwater C) a marine bony fish D) a freshwater bony fish E) a shark inhabiting freshwater Lake Nicaragua

C) a marine bony fish

What would account for increased urine production as a result of drinking alcoholic beverages? A) increased aldosterone production B) increased blood pressure C) inhibition of antidiuretic hormone secretion (ADH) D) increased reabsorption of water in the proximal tubule E) the osmoregulator cells of the brain increasing their activity

C) inhibition of antidiuretic hormone secretion (ADH)

Which group possess excretory organs known as Malpighian tubules? A) earthworms B) flatworms C) insects D) jellyfish E) sea stars

C) insects

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) isoosmotic.

Processing of filtrate in the proximal and distal tubules accomplishes what important function? A) sorting plasma proteins according to size B) converting toxic ammonia to less toxic urea C) maintaining a constant pH in body fluids D) regulating the speed of blood flow through the nephron E) reabsorbing urea to maintain osmotic balance

C) maintaining a constant pH in body fluids

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) proteins and nucleic acids.

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 which is conducive to the function of flight in terms of weight. D) excretion allows birds to live in desert environments.

C) requires little water for nitrogenous waste disposal which is conducive to the function of flight in terms of weight.

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) selective reabsorption

Which of the following is true of urea? It 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) the primary nitrogenous waste product of humans.

Unlike most bony fishes, sharks maintain body fluids that are isoosmotic to sea water. They are therefore considered by many to be osmoconformers because of the unusual way they maintain homeostasis. They osmoregulate 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 sea water osmolarity. D) synthesizing trimethylamine oxide, a chemical that speeds salt removal from cells. E) possessing a special adaptation that allows their cells to operate at an unusually high salt concentration.

C) tolerating high urea concentrations that balance internal salt concentrations to sea water osmolarity.

Which of the following nitrogenous wastes requires hardly any water for its excretion? A) amino acid B) urea C) uric acid D) ammonia E) nitrogen gas

C) uric acid

What is the typical osmolarity of human blood? A) 30 mosm/L B) 100 mosm/L C) 200 mosm/L D) 300 mosm/L E) 500 mosm/L

D) 300 mosm/L

How does ADH function at the cellular level? A) ADH stimulates the reabsorption of glucose through channel proteins. B) It triggers the synthesis of an enzyme that makes the phospholipid bilayer more permeable to water. C) It causes membranes to include more phospholipids that have unsaturated fatty acids. D) It causes an increase in the number of aquaporin molecules of collecting duct cells. E) It decreases the speed at which filtrate flow through the nephron leading to increased reabsorption of water.

D) It causes an increase in the number of aquaporin molecules of collecting duct cells.

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 the desert E) a beaver

D) a mouse species living in the desert

What substance is secreted by the proximal-tubule cells and prevents the pH of urine from becoming too acidic? A) bicarbonate B) salt C) glucose D) ammonia E) NaOH

D) ammonia

Which one of the following, if present in a urine sample, would likely be caused by trauma? A) amino acids B) glucose C) salts D) erythrocytes E) vitamins

D) erythrocytes

Which of the following processes of osmoregulation by the kidney is the least selective? A) salt pumping to control osmolarity B) H+ pumping to control pH C) reabsorption D) filtration E) secretion

D) filtration

The transfer of fluid from the glomerulus to Bowmanʹs 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 to the Bowmanʹs capsule.

D) is mainly a consequence of blood pressure in the capillaries of the glomerulus

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) isoosmotic; saltwater

Unlike an earthwormʹs 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) receives filtrate from blood instead of coelomic fluid.

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) diffusion of salt from the descending limb of the loop of Henle.

Which of the following mechanisms for osmoregulation or nitrogen removal is correctly paired with its corresponding animal? A) metanephridium-flatworm B) Malpighian tubule-frog C) kidney-insect D) flame bulb-snake E) direct cellular exchange-marine invertebrate

E) direct cellular exchange-marine invertebrate

Which structure increases the reabsorption of Na+ when stimulated by aldosterone? A) loop of Henle B) collecting duct C) Bowmanʹs capsule D) proximal tubule E) distal tubules

E) distal tubules

Which feature of osmoregulation is found in both marine and freshwater bony fish? 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) gain of water through food

Which of the following excretory systems is partly based on the filtration of fluid under high hydrostatic pressure? A) flame-bulb system of flatworms B) protonephridia of rotifers C) metanephridia of earthworms D) Malpighian tubules of insects E) kidneys of vertebrates

E) kidneys of vertebrates

What is the main nitrogenous waste excreted by birds? A) ammonia B) nitrate C) nitrite D) urea E) uric acid

E) uric acid