Deck 44: Osmoregulation and Excretion

Question 1

Developing bird embryos excrete most of their nitrogenous waste as uric acid because ________.

A) it is less metabolically expensive to produce compared to other waste products
B) it has a low solubility in water and is less toxic to the embryo than other forms of waste
C) it requires less energy to transport across the egg shell
D) it can be recycled by the embryo to make new protein

Answer 1

B

Question 2

Animals have adapted different mechanisms for excreting nitrogenous waste products. Which of the following are selective pressures that likely influence which mechanism an animal uses?
I) the amount of water available in the animal's habitat
II) the energy needs of the animal
III) the temperature of the animal's environment

A) only I and III
B) only II and III
C) only I and II
D) I, II, and III

Answer 2

C

Question 3

Which nitrogenous waste has the greatest number of nitrogen atoms?

A) ammonia
B) ammonium ions
C) urea
D) uric acid

Answer 3

D

Question 4

Like other osmoregulatory animals that live in marine environments, sharks maintain tissue concentrations of sodium, potassium, and chloride that are hypoosmotic to the seawater. In contrast to the bony marine fishes, however, sharks do not need to drink seawater. Why?

A) High urea and trimethylamine oxide concentrations keep shark tissues slightly hyperosmotic relative to seawater, so water is absorbed passively.
B) Sodium, chloride, and potassium do not influence water balance in shark tissues.
C) Shark blood is hypotonic to the surrounding tissues, so water always moves passively into the tissue from the blood.
D) Sharks excrete large quantities of salt through their gills in exchange for water.

Question 5

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) synthesising trimethylamine oxide, a chemical that binds and precipitates salts inside cells

Question 6

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

Question 7

Salmon eggs hatch in fresh water. The fish then migrate to the ocean (a hypertonic solution) and, after several years of feeding and growing, return to fresh water to breed. How can these organisms make the transition from fresh water to ocean water and back to fresh water?

A) The rectal gland functions in the ocean water, and chloride cells function in fresh water.
B) The salt transport mechanisms of the gill epithelia change during migration.
C) Salmon in fresh water excrete concentrated urine, and salmon in salt water secrete dilute urine.
D) Their metabolism changes in salt water to degrade electrolytes.

Question 8

The body fluids of an osmoconformer would be ________ with its ________ environment

A) hyperosmotic; freshwater
B) hyperosmotic; seawater
C) isoosmotic; seawater
D) hypoosmotic; seawater

Question 9

The fluid with the highest osmolarity is ________.

A) distilled water
B) blood in birds
C) blood in mammals
D) seawater in a rock pool

Question 10

Single-celled Paramecium live in pond water (a hypotonic environment relative to the cytosol). They have a structural feature, a contractile vacuole, which enables them to osmoregulate. If sucrose or saline was added to the pond water in different concentrations (in millimolars, mM), under which conditions 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

Question 11

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

Question 12

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

Question 13

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

Question 14

Compared to the seawater around them, most marine invertebrates are ________.

A) hyperosmotic
B) hypoosmotic
C) isoosmotic
D) both hyperosmotic and isoosmotic

Question 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) a terrestrial environment, such as that supporting crickets
D) a moist system of burrows, such as those of naked mole rats

Question 16

An examination of a marine star fish that had 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 kidney had ruptured
D) its cells dehydrated and lost the ability to metabolise

Question 17

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 ageing

Question 18

An examination 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

Question 19

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) plain
D) mallee

Question 20

What role do transport epithelia play in osmoregulation of marine fish with bony skeletons?

A) They actively transport salt into the animal through the gills.
B) They mediate the movement of water from seawater through the gills.
C) They are involved in excretion of excess salt.
D) They allow the fish to produce dilute urine.

Question 21

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.

Question 22

Which of the following is characteristic of juxtamedullary nephrons?

A) large Bowman's capsule
B) absence of proximal tubule
C) limited branching of vasa recta
D) long loop of Henle

Question 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

Question 24

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 synthesise 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.

Question 25

Use the following figure to answer the question. Filtration takes place in the structure labelled ________.

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

Question 26

The osmoregulatory/excretory system of a freshwater flatworm is based on the operation of ________.

A) protonephridia
B) metanephridia
C) Malpighian tubules
D) nephrons

Question 27

The advantage of excreting nitrogenous wastes as urea rather than as ammonia is that ________.

A) urea can be removed as a semi-solid paste
B) urea is less toxic than ammonia
C) urea does not affect the osmotic gradient
D) less nitrogen is removed from the body

Question 28

Among the following choices, the most concentrated urine is excreted by ________.

A) frogs
B) kangaroo rats
C) humans
D) freshwater bass

Question 29

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

Question 30

Birds secrete uric acid as their nitrogenous waste because uric acid ________.

A) is readily soluble in water
B) is metabolically less expensive to synthesise 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

Question 31

Studies of cricket Malpighian tubules revealed that potassium ions accumulated inside the tubule, moving against the potassium concentration gradient. Based on the information, what can you infer about the mechanism of potassium 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.
D) Sodium ions will follow potassium ions.

Question 32

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

Question 33

Which process in the nephron is least selective?

A) filtration
B) reabsorption
C) active transport
D) secretion

Question 34

Choose a pair that correctly associates the mechanism for osmoregulation or nitrogen removal with the appropriate animal.

A) protonephridium-earthworm
B) Malpighian tubule-frog
C) flame bulb-flat worm
D) exchange across the body surface-snake

Question 35

Materials are returned to the blood from the filtrate by which of the following processes?

A) filtration
B) reabsorption
C) secretion
D) excretion

Question 36

Within a normally functioning kidney, red blood cells can be found in ________.

A) the vasa recta
B) Bowman's capsule
C) the proximal tubule
D) the collecting duct

Question 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 sub-protein-sized molecules are transferred
D) is mainly a consequence of blood pressure in the capillaries of the glomerulus

Question 38

Studies of cricket Malpighian tubules revealed that potassium ions accumulated inside the tubule, moving against the potassium concentration gradient. How would you expect the movement of water to be influenced by the distribution of potassium ions?

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.

Question 39

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

Question 40

Excretory organs known as "Malpighian tubules" are present in ________.

A) flatworms
B) insects
C) jellyfish
D) star fish

Question 41

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

Question 42

Use the following figure to answer the question. The structure labelled ________ can be influenced by hormones to change the concentration of the urine.

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

Question 43

A human who has no access to fresh water but is forced to drink seawater instead will ________.

A) produce excessive antidiuretic hormone to remove more water but hold back salts
B) passively excrete excess water in order to remove the high concentration of ingested salt
C) release atrial natriuretic peptide to decrease blood pressure
D) risk becoming overhydrated within 12 hours

Question 44

Use the following figure to answer the question. In which of the labelled structures does passive water reabsorption take place?

A) only in B
B) only in B and D
C) in B, C, and E
D) Passive water reabsorption occurs throughout all of the nephron.

Question 45

Antidiuretic hormone (ADH) and the renin-angiotensin-aldosterone system (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 both 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.

Question 46

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

Question 47

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

Question 48

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

Question 49

Which of the following contribute to maintaining the high osmolarity of the renal medulla?
I) active transport of salt from the upper region of the ascending limb
II) the spatial arrangement of juxtamedullary nephrons
III) diffusion of urea from the collecting duct
IV) diffusion of salt from the descending limb of the loop of Henle

A) All of these conditions contribute to the osmolarity of the medulla.
B) I, II, and III
C) I and IV
D) I, II, and IV

Question 50

Which process in the nephron is least selective?

A) filtration
B) reabsorption
C) active transport
D) secretion

Question 51

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

Question 52

Osmoregulatory adjustment via the atrial natriuretic peptide 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

Question 53

Natural selection should favour the highest proportion of juxtamedullary nephrons in which of the following species?

A) a platypus
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

Question 54

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

Question 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

Question 56

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

Question 57

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

Question 58

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

Question 59

Use the following figure to answer the question. Selective secretion of toxins and drugs takes place in the structure labelled ________.

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

Question 60

Unlike an earthworm's metanephridia, a mammalian nephron

A) is intimately associated with a capillary network.
B) functions in both osmoregulation and excretion.
C) receives filtrate from blood instead of coelomic fluid.
D) has a transport epithelium.

Question 61

Which of the following animals generally has the lowest volume of urine production?

A) vampire bat
B) salmon in fresh water
C) marine bony fish
D) freshwater flatworm

Question 62

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.

Question 63

In which of the following species should natural selection favour the highest proportion of juxtamedullary nephrons?

A) a platypus
B) a mouse species living in a temperate broadleaf forest
C) a mouse species living in a desert
D) a seal

Question 64

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 synthesise than ammonia.
B) Small stagnant pools do not provide enough water to dilute ammonia, which is toxic.
C) Urea forms an insoluble precipitate.
D) Urea makes lungfish tissue hypoosmotic to the pool.