Lecture 14: Osmoregulation on Land Part 2

Question 1

What is the primary role of the kidneys in maintaining homeostasis?
a) Regulating body temperature
b) Maintaining a balance of water, salts, and minerals in the blood
c) Producing metabolic water
d) Excreting carbon dioxide

Answer 1

Answer: b) Maintaining a balance of water, salts, and minerals in the blood

Question 2

How do kidneys contribute to blood pressure regulation?
a) By regulating glucose levels in the blood
b) By filtering large volumes of blood at once
c) By adjusting water and ion concentrations
d) By producing oxygen

Answer 2

Answer: c) By adjusting water and ion concentrations

Question 3

What can happen if the balance of ions (e.g., sodium, potassium, calcium) in the body is disrupted?
a) Increased metabolic water production
b) Malfunction of nerves, muscles, and other tissues
c) Overproduction of urine
d) Reduction in cellular respiration

Answer 3

Answer: b) Malfunction of nerves, muscles, and other tissues

Question 4

Which of the following is a general feature of kidneys across taxa?
a) Production of oxygen during filtration
b) Elimination of aqueous solutions derived from body fluids
c) Direct absorption of nutrients from the blood
d) Excretion of gases such as nitrogen

Answer 4

Answer: b) Elimination of aqueous solutions derived from body fluids

Question 5

How do kidneys differ across taxa?
a) Mammalian kidneys are the only ones that produce filtrate.
b) Amphibian kidneys function primarily for water conservation.
c) The tubular elements and mechanisms vary to meet specific environmental needs.
d) All vertebrate kidneys produce the same concentration of urine.

Answer 5

Answer: c) The tubular elements and mechanisms vary to meet specific environmental needs.

Question 6

What is the role of filtration in kidney function?
a) To secrete solutes into the blood
b) To produce a filtrate of blood by separating waste and useful components
c) To excrete urine directly into the bloodstream
d) To reabsorb solutes from the body fluids

Answer 6

Answer: b) To produce a filtrate of blood by separating waste and useful components

Question 7

Which process involves returning useful solutes from the filtrate back to the blood?
a) Filtration
b) Secretion
c) Reabsorption
d) Excretion

Answer 7

Answer: c) Reabsorption

Question 8

What happens during the secretion phase of kidney function?
a) Waste solutes are removed from the filtrate.
b) Useful solutes are added to the blood.
c) Additional solutes are added to the filtrate from the blood.
d) Water is conserved through osmotic processes.

Answer 8

Answer: c) Additional solutes are added to the filtrate from the blood.

Question 9

If a freshwater fish’s kidneys could not reabsorb ions efficiently, what would likely happen?
a) The fish would retain too much salt in its blood.
b) The fish would excrete urine with a high concentration of ions.
c) The fish would excrete large volumes of very dilute urine.
d) The fish would absorb more salt through its gills.

Answer 9

Answer: b) The fish would excrete urine with a high concentration of ions.

Question 10

. In humans, how does kidney dysfunction affect blood pressure?
a) It causes immediate dehydration and lowers blood pressure.
b) It impairs ion regulation, potentially leading to increased blood pressure.
c) It reduces water reabsorption, causing hypertension.
d) It enhances blood filtration, lowering blood pressure.

Answer 10

Answer: b) It impairs ion regulation, potentially leading to increased blood pressure.

Question 11

What is the function of the fenestrated capillaries in the glomerulus?
a) To reabsorb nutrients from the filtrate
b) To allow selective passage of nitrogenous wastes, water, and solutes while retaining larger elements like red blood cells
c) To secrete ions directly into the filtrate
d) To prevent all fluid from exiting the bloodstream

Answer 11

Answer: b) To allow selective passage of nitrogenous wastes, water, and solutes while retaining larger elements like red blood cells

Question 12

What structure in the nephron collects the filtrate immediately after it passes through the glomerulus?
a) Proximal convoluted tubule
b) Distal convoluted tubule
c) Bowman’s capsule
d) Collecting duct

Answer 12

Answer: c) Bowman’s capsule

Question 13

Which process occurs in the proximal convoluted tubule?
a) Initial filtration of blood
b) Reabsorption of water, ions, and nutrients
c) Secretion of additional solutes into the filtrate
d) Collection of urine for excretion

Answer 13

Answer: b) Reabsorption of water, ions, and nutrients

Question 14

Which animals have a nephron structure similar to that of amphibians and reptiles?
a) Birds and mammals
b) Fish and amphibians
c) Snakes and lizards
d) Mammals only

Answer 14

Answer: c) Snakes and lizards

Question 15

How does the nephron structure of birds and mammals differ from that of amphibians and reptiles?
a) Birds and mammals have longer nephrons for water conservation.
b) Birds and mammals lack Bowman’s capsules.
c) Amphibians and reptiles have a Loop of Henle, while birds and mammals do not.
d) Birds and mammals excrete urine directly into the bloodstream.

Answer 15

Answer: a) Birds and mammals have longer nephrons for water conservation.

Question 16

What is the role of the collecting duct in the nephron?
a) It filters blood plasma.
b) It reabsorbs essential solutes from the filtrate.
c) It collects processed filtrate (urine) from multiple nephrons and directs it to the ureter.
d) It secretes ions into the distal tubule.

Answer 16

Answer: c) It collects processed filtrate (urine) from multiple nephrons and directs it to the ureter.

Question 17

Why does the proximal convoluted tubule have microvilli?
a) To enhance filtration efficiency
b) To increase the surface area for reabsorption of solutes and water
c) To actively secrete toxins into the filtrate
d) To prevent water loss

Answer 17

Answer: b) To increase the surface area for reabsorption of solutes and water

Question 18

What happens to the filtrate as it travels through the intermediate segment (Loop of Henle) in mammals?
a) Solutes and water are actively secreted into the tubule.
b) Water is reabsorbed, concentrating the filtrate.
c) It becomes less concentrated due to passive ion absorption.
d) It remains unchanged until reaching the distal convoluted tubule.

Answer 18

Answer: b) Water is reabsorbed, concentrating the filtrate.

Question 19

What would happen if the fenestrations in the glomerular capillaries become blocked?
a) Filtration would stop, leading to a buildup of wastes in the blood.
b) Reabsorption in the proximal tubule would increase.
c) Urine production would become excessive and dilute.
d) Blood pressure would decrease significantly.

Answer 19

Answer: a) Filtration would stop, leading to a buildup of wastes in the blood.

Question 20

What are the two main layers of the mammalian kidney?
a) Cortex and Bowman’s capsule
b) Cortex and medulla
c) Medulla and renal tubule
d) Glomerulus and collecting duct

Answer 20

Answer: b) Cortex and medulla

Question 21

Where in the kidney are the glomerulus and Bowman’s capsule located?
a) In the medulla
b) In the cortex
c) In the renal pelvis
d) In the renal pyramid

Answer 21

Answer: b) In the cortex

Question 22

Why is the size of the medulla important in mammalian kidneys?
a) It determines the volume of urine that can be produced.
b) It allows adjustment of the length of the renal tubule to conserve water in desert species.
c) It controls the pressure exerted by the glomerulus.
d) It ensures blood pressure regulation within the kidney.

Answer 22

Answer: b) It allows adjustment of the length of the renal tubule to conserve water in desert species.

Question 23

What is the primary function of Bowman’s capsule?
a) To produce urea from nitrogenous waste
b) To collect filtrate from the blood passing through the glomerulus
c) To reabsorb essential nutrients into the bloodstream
d) To secrete solutes into the renal tubule

Answer 23

Answer: b) To collect filtrate from the blood passing through the glomerulus

Question 24

How does the glomerulus filter blood?
a) By secreting enzymes that break down solutes
b) By exerting high blood pressure to force fluid and small solutes through fenestrations
c) By active transport through the capillary walls
d) By selectively absorbing ions into the renal tubule

Answer 24

Answer: b) By exerting high blood pressure to force fluid and small solutes through fenestrations

Question 25

What type of molecules pass through the fenestrations in the glomerular capillaries?
a) Large proteins and red blood cells
b) Water, glucose, amino acids, and urea
c) Hormones and lipids
d) White blood cells and platelets

Answer 25

Answer: b) Water, glucose, amino acids, and urea

Question 26

What is ultrafiltration in the kidney?
a) The selective absorption of solutes in the proximal tubule
b) The active secretion of ions into the nephron tubule
c) The process of blood pressure forcing water and solutes through the glomerulus into Bowman’s capsule
d) The collection of urine in the collecting duct

Answer 26

Answer: c) The process of blood pressure forcing water and solutes through the glomerulus into Bowman’s capsule

Question 27

Which factors contribute to the process of ultrafiltration?
a) Low blood pressure and passive diffusion
b) High blood pressure and fenestrated capillaries in the glomerulus
c) Osmotic gradients and microvilli in Bowman’s capsule
d) Active transport in the collecting duct

Answer 27

Answer: b) High blood pressure and fenestrated capillaries in the glomerulus

Question 28

If blood pressure in the glomerulus drops significantly, what is the likely outcome?
a) Increased filtration of nitrogenous waste
b) Decreased filtration and buildup of waste products in the blood
c) Increased urine production with lower solute concentration
d) Enhanced ultrafiltration due to lower resistance

Answer 28

Answer: b) Decreased filtration and buildup of waste products in the blood

Question 29

What would happen if podocytes in Bowman’s capsule were damaged?
a) Filtration would stop, and blood pressure would increase.
b) Large molecules like proteins might pass into the filtrate.
c) The kidney would be unable to secrete ions into the nephron.
d) Blood flow through the nephron would cease.

Answer 29

Answer: b) Large molecules like proteins might pass into the filtrate.

Question 30

What is unique about the mammalian kidney compared to other vertebrates?
a) Mammalian kidneys produce isosmotic urine.
b) Mammalian kidneys produce hyperosmotic urine due to the Loop of Henle.
c) Mammalian kidneys lack a Loop of Henle.
d) Mammalian kidneys excrete urine directly into the bloodstream.

Answer 30

Answer: b) Mammalian kidneys produce hyperosmotic urine due to the Loop of Henle.

Question 31

What structural feature of the Loop of Henle allows for the production of concentrated urine?
a) Its short, straight tubule structure
b) Its long tubule, creating a gradient in osmotic pressure between the cortex and medulla
c) Its impermeability to water in both limbs
d) Its lack of active transport mechanisms

Answer 31

Answer: b) Its long tubule, creating a gradient in osmotic pressure between the cortex and medulla

Question 32

What type of nephron contains a Loop of Henle?
a) Only mammalian-type nephrons
b) Amphibian and mammalian nephrons
c) All vertebrate nephrons
d) Non-mammalian nephrons

Answer 32

Answer: a) Only mammalian-type nephrons

Question 33

What happens in the descending limb of the Loop of Henle?
a) Sodium and chloride ions are reabsorbed via active transport.
b) Water leaves the tubule by osmosis, concentrating the filtrate.
c) Glucose and amino acids are secreted into the tubule.
d) Sodium is actively pumped into the interstitial fluid.

Answer 33

Answer: b) Water leaves the tubule by osmosis, concentrating the filtrate.

Question 34

Why is the ascending limb of the Loop of Henle impermeable to water?
a) To ensure water is actively reabsorbed into the blood.
b) To allow active transport of NaCl, creating a concentration gradient in the interstitial fluid.
c) To prevent the filtrate from becoming more concentrated.
d) To reduce the energy required for active transport of solutes.

Answer 34

Answer: b) To allow active transport of NaCl, creating a concentration gradient in the interstitial fluid.

Question 35

What is the role of the osmotic gradient established by the Loop of Henle?
a) It allows for active reabsorption of glucose and amino acids.
b) It concentrates the interstitial fluid in the medulla, facilitating water reabsorption from the collecting duct.
c) It dilutes the filtrate to form hypoosmotic urine.
d) It equalizes the osmotic pressure between the cortex and medulla.

Answer 35

Answer: b) It concentrates the interstitial fluid in the medulla, facilitating water reabsorption from the collecting duct.

Question 36

What would happen if active transport in the ascending limb of the Loop of Henle were inhibited?
a) The osmotic gradient in the medulla would collapse, and urine would become dilute.
b) The descending limb would stop reabsorbing water.
c) Filtrate would become more concentrated as it ascends.
d) Glucose reabsorption in the proximal tubule would cease.

Answer 36

Answer: a) The osmotic gradient in the medulla would collapse, and urine would become dilute.

Question 37

Which protein channels are essential for water reabsorption in the proximal tubule and descending Loop of Henle?
a) Sodium-potassium pumps
b) Aquaporins
c) Chloride channels
d) Urea transporters

Answer 37

Answer: b) Aquaporins

Question 38

A desert mammal has an exceptionally long Loop of Henle. What advantage does this adaptation provide?
a) It increases the surface area for glucose reabsorption.
b) It enhances the ability to produce highly concentrated urine, conserving water.
c) It allows the animal to excrete urea at a higher rate.
d) It ensures the production of dilute urine in low-humidity environments.

Answer 38

Answer: b) It enhances the ability to produce highly concentrated urine, conserving water.

Question 39

What is the “single effect” in the Loop of Henle?
a) The difference in osmolarity between the filtrate in the descending and ascending limbs of the Loop of Henle
b) The active transport of water in the ascending limb
c) The production of isosmotic urine in the nephron
d) The reabsorption of glucose and amino acids in the proximal tubule

Answer 39

Answer: a) The difference in osmolarity between the filtrate in the descending and ascending limbs of the Loop of Henle

Question 40

How is the single effect generated in the Loop of Henle?
a) By the active pumping of NaCl out of the ascending limb into the interstitial fluid
b) By passive diffusion of water into the ascending limb
c) By filtration of solutes into Bowman’s capsule
d) By secretion of solutes into the collecting duct

Answer 40

Answer: a) By the active pumping of NaCl out of the ascending limb into the interstitial fluid

Question 41

Why is water unable to follow NaCl out of the ascending limb?
a) Because the ascending limb is impermeable to water
b) Because there is no osmotic gradient
c) Because water is actively transported back into the descending limb
d) Because NaCl diffusion occurs too rapidly

Answer 41

Answer: a) Because the ascending limb is impermeable to water

Question 42

What is the primary role of countercurrent multiplication in the Loop of Henle?
a) To establish a horizontal osmolarity gradient across the loop
b) To create a vertical osmolarity gradient in the interstitial fluid of the medulla
c) To dilute the filtrate in the descending limb
d) To directly produce urine in the nephron

Answer 42

Answer: b) To create a vertical osmolarity gradient in the interstitial fluid of the medulla

Question 43

During countercurrent multiplication, what happens to the fluid as it moves down the descending limb of the Loop of Henle?
a) Water is reabsorbed, and the filtrate becomes more concentrated.
b) NaCl is actively transported into the interstitial fluid, and the filtrate becomes less concentrated.
c) Glucose and amino acids are secreted into the filtrate.
d) Water is secreted into the filtrate, and osmolarity decreases.

Answer 43

Answer: a) Water is reabsorbed, and the filtrate becomes more concentrated.

Question 44

What is the effect of countercurrent multiplication on osmolarity in the ascending limb?
a) Osmolarity increases as solutes are actively transported into the interstitial fluid.
b) Osmolarity decreases as NaCl is actively transported out, and water remains in the filtrate.
c) Osmolarity remains constant due to passive transport.
d) Osmolarity decreases due to the passive diffusion of water.

Answer 44

Answer: b) Osmolarity decreases as NaCl is actively transported out, and water remains in the filtrate.

Question 45

How does the single effect contribute to countercurrent multiplication?
a) It increases osmolarity at the top of the Loop of Henle.
b) It creates a horizontal osmolarity difference that is multiplied vertically by fluid movement.
c) It establishes a uniform concentration gradient along the nephron.
d) It increases the concentration of glucose in the filtrate.

Answer 45

Answer: b) It creates a horizontal osmolarity difference that is multiplied vertically by fluid movement.

Question 46

If the NaCl pumps in the ascending limb were inhibited, what would happen to the medullary osmolarity gradient?
a) It would increase, concentrating the urine further.
b) It would collapse, resulting in dilute urine.
c) It would remain the same, as water would compensate for the loss of NaCl.
d) It would cause the filtrate in the descending limb to become hypoosmotic.

Answer 46

Answer: b) It would collapse, resulting in dilute urine.

Question 47

In countercurrent multiplication, why does the filtrate osmolarity increase as it moves down the descending limb?
a) Because solutes are actively transported into the filtrate
b) Because water is reabsorbed into the interstitial fluid due to its high osmolarity
c) Because NaCl diffuses into the descending limb
d) Because the descending limb actively secretes water

Answer 47

Answer: b) Because water is reabsorbed into the interstitial fluid due to its high osmolarity

Question 48

A patient has a damaged Loop of Henle, and their medullary osmolarity gradient is reduced. What effect will this have on their urine concentration?
a) The urine will become more concentrated.
b) The urine will be dilute due to the inability to reabsorb water effectively.
c) The urine concentration will remain unchanged.
d) The urine will become hyperosmotic compared to the blood.

Answer 48

Answer: b) The urine will be dilute due to the inability to reabsorb water effectively.

Question 49

How does the collecting duct contribute to urine concentration?
a) It passively secretes water into the urine.
b) It equilibrates with the osmotic pressure of the surrounding interstitial fluid by reabsorbing water through aquaporins.
c) It actively transports NaCl into the interstitial fluid, making the urine hyperosmotic.
d) It prevents water loss by blocking aquaporins.

Answer 49

Answer: b) It equilibrates with the osmotic pressure of the surrounding interstitial fluid by reabsorbing water through aquaporins.

Question 50

What happens to water in the collecting duct during diuresis?
a) Water is reabsorbed into the bloodstream.
b) Water remains trapped in the tubule due to low aquaporin levels, leading to dilute urine.
c) Water is actively transported into the interstitial fluid.
d) Water follows sodium into the interstitial space.

Answer 50

Answer: b) Water remains trapped in the tubule due to low aquaporin levels, leading to dilute urine.

Question 51

In which condition does the kidney produce highly concentrated urine?
a) Low levels of antidiuretic hormone (ADH)
b) High levels of aquaporins in the collecting duct
c) Increased permeability of the ascending limb of the Loop of Henle to water
d) Reduced osmotic pressure in the interstitial fluid

Answer 51

Answer: b) High levels of aquaporins in the collecting duct

Question 52

What is the role of aquaporins in the nephron?
a) To actively transport NaCl into the interstitial fluid
b) To facilitate the passive movement of water across cell membranes
c) To regulate the secretion of solutes into the filtrate
d) To create the single effect in the Loop of Henle

Answer 52

Answer: b) To facilitate the passive movement of water across cell membranes

Question 53

How does ADH affect aquaporin activity in the collecting duct?
a) ADH increases the insertion of aquaporins into the membrane, enhancing water reabsorption.
b) ADH blocks aquaporins, preventing water reabsorption and producing dilute urine.
c) ADH removes aquaporins from the membrane, reducing water permeability.
d) ADH stimulates active transport of water into the interstitial fluid.

Answer 53

Answer: a) ADH increases the insertion of aquaporins into the membrane, enhancing water reabsorption.

Question 54

Which condition is characterized by low ADH levels?
a) Diuresis, where dilute urine is produced
b) Antidiuresis, where concentrated urine is produced
c) Increased NaCl reabsorption in the collecting duct
d) Water retention in the interstitial fluid

Answer 54

Answer: a) Diuresis, where dilute urine is produced

Question 55

What would happen if ADH levels were abnormally high?
a) Water reabsorption in the collecting duct would increase, producing concentrated urine.
b) NaCl transport in the Loop of Henle would increase, producing dilute urine.
c) The osmotic gradient in the medulla would collapse.
d) Aquaporin levels in the collecting duct would decrease, preventing water reabsorption.

Answer 55

Answer: a) Water reabsorption in the collecting duct would increase, producing concentrated urine.

Question 56

If the osmolarity of the interstitial fluid in the medulla is reduced, how will urine concentration be affected?
a) Urine will be more concentrated due to reduced water loss.
b) Urine will be dilute because the osmotic gradient driving water reabsorption is disrupted.
c) Urine concentration will increase because of enhanced NaCl transport.
d) Urine concentration will remain unchanged.

Answer 56

Answer: b) Urine will be dilute because the osmotic gradient driving water reabsorption is disrupted.

Question 57

What happens in the absence of ADH (antidiuretic hormone)?
a) The collecting duct becomes highly permeable to water, concentrating the urine.
b) The collecting duct becomes less permeable to water, resulting in dilute urine.
c) Aquaporins are inserted into the nephron, increasing water reabsorption.
d) Sodium reabsorption in the proximal tubule decreases.

Answer 57

Answer: b) The collecting duct becomes less permeable to water, resulting in dilute urine.

Question 58

Which of the following substances can act as diuretics by interfering with ADH activity?
a) Caffeine and alcohol
b) Antihistamines and glucose
c) Aquaporins and sodium
d) Urea and proteins

Answer 58

Answer: a) Caffeine and alcohol

Question 59

In the presence of high levels of ADH, what happens in the collecting duct?
a) Aquaporins are removed, preventing water reabsorption.
b) Aquaporins are inserted into the membrane, increasing water reabsorption.
c) Sodium reabsorption is inhibited, producing dilute urine.
d) Filtrate osmolarity increases due to urea secretion.

Answer 59

Answer: b) Aquaporins are inserted into the membrane, increasing water reabsorption.

Question 60

Why do desert animals, like kangaroo rats, have a long Loop of Henle?
a) To produce more dilute urine and conserve solutes.
b) To maximize the osmotic gradient and produce highly concentrated urine.
c) To increase the surface area for glucose reabsorption.
d) To reduce the need for urea excretion.

Answer 60

Answer: b) To maximize the osmotic gradient and produce highly concentrated urine.

Question 61

What is the significance of thicker medullas in desert animals compared to aquatic animals?
a) Thicker medullas reduce water reabsorption, producing dilute urine.
b) Thicker medullas allow for a steeper osmotic gradient, enhancing urine concentration.
c) Thicker medullas improve sodium secretion, reducing urine osmolarity.
d) Thicker medullas eliminate the need for ADH regulation.

Answer 61

Answer: b) Thicker medullas allow for a steeper osmotic gradient, enhancing urine concentration.

Question 62

Where is osmotic pressure highest in the nephron?
a) Proximal convoluted tubule
b) Distal convoluted tubule
c) Inner medulla near the Loop of Henle
d) Collecting duct in the cortex

Answer 62

Answer: c) Inner medulla near the Loop of Henle

Question 63

How does osmolarity change as filtrate moves through the descending limb of the Loop of Henle?
a) Osmolarity decreases as water is reabsorbed.
b) Osmolarity increases as water leaves the tubule and enters the interstitial fluid.
c) Osmolarity remains constant due to sodium reabsorption.
d) Osmolarity decreases due to active transport of NaCl.

Answer 63

Answer: b) Osmolarity increases as water leaves the tubule and enters the interstitial fluid.

Question 64

Which of the following waste products is most toxic but requires the least energy to produce?
a) Urea
b) Uric acid
c) Ammonia
d) Carbon dioxide

Answer 64

Answer: c) Ammonia

Question 65

What is the primary nitrogenous waste excreted by most aquatic animals?
a) Ammonia (ammonotelism)
b) Uric acid (uricotelism)
c) Urea (ureotelism)
d) Nitrite

Answer 65

Answer: a) Ammonia (ammonotelism)

Question 66

Why do terrestrial animals such as mammals primarily excrete urea?
a) Urea is non-toxic and requires less energy than uric acid to produce.
b) Urea can be excreted without water.
c) Urea is highly toxic but requires minimal energy to produce.
d) Urea is the most energy-efficient compound to store nitrogen.

Answer 66

Answer: a) Urea is non-toxic and requires less energy than uric acid to produce.

Question 67

Birds and reptiles excrete nitrogenous waste as uric acid because:
a) It is the least toxic and requires the least amount of water for excretion.
b) It is highly soluble in water and can be excreted easily.
c) It is produced without any energy cost.
d) It can be stored in eggs without harming the developing embryo.

Answer 67

Answer: d) It can be stored in eggs without harming the developing embryo.

Question 68

Why do aquatic animals typically excrete ammonia instead of urea or uric acid?
a) They lack enzymes for urea production.
b) Ammonia is highly soluble in water and can diffuse directly into the aquatic environment.
c) Urea and uric acid are toxic in aquatic environments.
d) Ammonia allows them to conserve water.

Answer 68

Answer: b) Ammonia is highly soluble in water and can diffuse directly into the aquatic environment.

Question 69

During metamorphosis, bullfrogs transition from ammonotelism to ureotelism because:
a) Ammonia becomes toxic in terrestrial environments.
b) Urea production is energetically cheaper.
c) Ammonia cannot be stored in their eggs.
d) Uric acid production is too slow.

Answer 69

Answer: a) Ammonia becomes toxic in terrestrial environments.

Question 70

What enzyme activity increases during the bullfrog’s metamorphosis to facilitate urea excretion?
a) Ornithine transcarbamoylase
b) Uricase
c) Ammonia synthase
d) Nitrite reductase

Answer 70

Answer: a) Ornithine transcarbamoylase

Question 71

Why do tadpoles primarily excrete ammonia rather than urea?
a) They live in water, which dilutes ammonia quickly.
b) Their enzyme systems for urea synthesis are underdeveloped.
c) Urea synthesis would require the energy they need for growth.
d) All of the above.

Answer 71

Answer: d) All of the above.