Test Prep for AP® Courses
Patients with kidney illnesses use dialysis machines to remove harmful urea from their blood. The blood is separated from a solution, called the dialysate, which is designed to remove wastes by diffusion through a semipermeable membrane, as shown in the diagram.
How does the concentration of solutes likely differ between the upper component of the dialyzer and the lower compartment, containing the fresh dialysate, for the dialysis to successfully remove wastes from the blood?
- In the upper component, the dialysate has a higher solute concentration than the blood, which allows the urea to diffuse to the lower dialysate down its concentration gradient.
- In the upper component, the dialysate has a lower solute concentration than the blood, which allows the urea to be separated via active transport down the concentration gradient.
- In the upper component, the dialysate has a higher solute concentration than the blood, which allows the urea to utilize facilitated diffusion in order to diffuse to the lower dialysate.
- In the upper component, the dialysate has a lower solute concentration than the blood, which allows the urea to diffuse to the lower dialysate down its concentration gradient.
The diagram shows red blood cells in two different NaCl solutions.
What is likely causing the cells to differ in shape in the two solutions?
- Solution A has high osmolarity. Solution B has low osmolarity.
- Solution A has low osmolarity. Solution B high osmolarity.
- The cells in solution A are osmoregulators. The cells in solution B are osmoconformers.
- The cells in solution A are osmoconformers. The cells in solution B are osmoregulators.
This diagram models the osmotic pressures experienced by a fish.
Based on the direction of water and solute movements shown in the diagram, is this fish likely a saltwater or freshwater fish? How do you know?
- freshwater, because the fish is osmoregulating in response to a hypertonic solution
- freshwater, because the fish is osmoregulating in response to a hypotonic solution
- saltwater, because the fish is osmoregulating in response to a hypertonic solution
- saltwater, because the fish is osmoregulating in response to a hypotonic solution
The diagram models the osmotic pressures experienced by a fish.
Why would this fish most likely drink little water but excrete dilute urine? Explain your answer in terms of the osmolarity of the water it lives in.
- The high osmolarity of the water would cause accumulation of too many salts in the body of the fish.
- The water it lives in has very low osmolarity, which causes water to constantly diffuse into the fish’s body.
- The water it lives in has very high osmolarity, which causes water to constantly diffuse out of the fish’s body.
- The water it lives in has very high osmolarity, which causes water to constantly diffuse into the fish’s body.
Patients with kidney illnesses use dialysis machines to remove harmful urea from their blood. The blood is separated from a solution, called the dialysate, that which is designed to remove wastes by diffusion through a semipermeable membrane, as shown in the diagram.
The semipermeable membrane is likely permeable to _____ and impermeable to _____.
- red blood cells, urea
- dialysate, blood plasma
- blood plasma, urea
- urea, red blood cells
The diagram models the countercurrent exchange mechanism within the loop of Henle. The numbers within the loop show the osmolarity of the filtrate, while the numbers between the two loops indicate the osmolarity of the interstitial fluid within the kidney tissue.
What would likely occur to the osmolarity of the filtrate in the lower ascending limb in the short term if the active transport of NaCl stopped?
- Filtrate osmolarity would increase, then decrease.
- Filtrate osmolarity would stay the same.
- Filtrate osmolarity would decrease.
- Filtrate osmolarity would increase.
The diagram models the countercurrent exchange mechanism within the loop of Henle. The numbers within the loop show the osmolarity of the filtrate, while the numbers between the two loops indicate the osmolarity of the interstitial fluid within the kidney tissue.
What would happen to the osmolarity of the interstitial fluid if water could not exit the descending limb?
- Osmolarity of the interstitial fluid would increase.
- Osmolarity of the interstitial fluid would decrease.
- There would be no change in the osmolarity.
- Osmolarity would increase or decrease depending upon the amount of water.
The diagram shows a cross-section of a kidney.
What would likely occur if there was a blood clot in the renal artery?
- Filtration in the glomerulus would decrease.
- Fluid levels in the renal pelvis would increase.
- Blood would not drain into the convoluted tubule.
- Urea production would increase.
The diagram shows the left kidney.
Why do the capillaries carrying blood from the renal artery run over the top of the renal pyramids?
- The capillaries deliver blood to the glomerulus and run parallel to the proximal convoluted tubule. Both are located in the medulla.
- The capillaries deliver blood to the glomerulus and run perpendicular to the proximal convoluted tubule. Both are located in the cortex.
- The capillaries deliver blood to the glomerulus and run perpendicular to the distal convoluted tubule. Both are located in the cortex.
- The capillaries deliver blood to the glomerulus and run parallel to the distal convoluted tubule. Both are located in the cortex.
The figure shows the components of a nephron located within the kidneys.
What would likely occur in the collecting duct if there was increased blood flow to the glomerulus?
- More water would enter the collecting duct.
- More urea would enter the collecting duct.
- Less NaCl would leave the collecting duct.
- Less urea would leave the collecting duct.
The figure shows the components of a nephron located within the kidneys.
Alcohol impairs the pituitary gland, which controls how much water is reabsorbed by the nephrons. The hormone produced by the pituitary gland, anti-diuretic hormone, increases water reabsorption by the kidney. How would impairment of this hormone likely affect the various components of the nephron pictured?
- Absorption of water from the filtrate would decrease, indicated by decreased loss of water in the descending loop of Henle, increased solute secretion into the distal tubule, and decreased water absorption in the collecting duct.
- Absorption of water from the filtrate would decrease, indicated by decreased loss of water in the ascending loop of Henle, increased solute secretion into the distal tubule, and increased water absorption in the collecting duct.
- Absorption of water from the filtrate would decrease, indicated by decreased loss of water in the ascending loop of Henle, increased solute secretion into the distal tubule, and decreased water absorption in the collecting duct.
- Absorption of water from the filtrate would decrease, indicated by decreased loss of water in the descending loop of Henle, increased solute secretion into the distal tubule, and increased water absorption in the collecting duct.
The diagram models the countercurrent exchange mechanism within the loop of Henle. The numbers within the loop show the osmolarity of the filtrate, while the numbers between the two loops indicate the osmolarity of the interstitial fluid within the kidney tissue.
What would likely happen to the osmolarity of the filtrate in the ascending limb if the body released urea into the interstitial fluid?
- The osmolarity would decrease, allowing the interstitial fluid to reabsorb solutes.
- The osmolarity would decrease, allowing the interstitial fluid to reabsorb water.
- The osmolarity would increase, allowing the interstitial fluid to reabsorb solutes.
- The osmolarity would increase, allowing the interstitial fluid to reabsorb water.
Planaria are flatworms that live in fresh water. Their excretory system, or protonephridia, consists of two tubules connected to a highly branched tube system. The intake end of the tubes contain cilia that propel waste matter down the tubules and out of the body through excretory pores that open on the body surface. Cilia also draw water from the interstitial fluid, allowing for filtration. Any valuable metabolites are recovered by reabsorption. What structure in the human kidneys most closely resembles the highly branched tube system of the protonephridia, and why?
- The renal artery, because it facilitates the exchange of nutrients with the blood.
- The convoluted tubule, because it facilitates the exchange of nutrients with the blood.
- The glomerulus, because it facilitates filtering of the blood.
- The ureter, because it facilitates filtering of the blood.
Planaria are flatworms that live in fresh water. Their excretory system, or protonephridia, consists of two tubules connected to a highly branched tube system. The intake end of the tubes contain cilia that propel waste matter down the tubules and out of the body through excretory pores that open on the body surface. Cilia also draw water from the interstitial fluid, allowing for filtration. Any valuable metabolites are recovered by reabsorption. What structure in the human kidneys most closely resembles the excretory pores of the protonephridia, and why?
- The urethral opening, because this is where wastes leave the body.
- The convoluted tubule, because this is where reabsorption and secretion occur.
- The glomerulus, because this is where reabsorption and secretion occur.
- The ureter, because this is where wastes leave the body.
- Water would be drawn out of the hemolymph within the tubule.
- Water would be drawn into the tubule.
- Ions would be drawn out of the hemolymph within the tubule.
- Ions would be drawn into the tubule.
- the ascending loop of henle
- the descending loop of henle
- the distal convoluted tubule
- Bowman's capsule
- They may evolve the ability to switch between uric acid and direct ammonia excretion.
- They would further reduce their excretion of ammonia.
- They may evolve the ability to excrete uric acid without having to dissolve it in any water.
- They would excrete higher concentrations of uric acid.
Birds and reptiles convert toxic ammonia to uric acid or the closely related compound guanine (guano), reflecting the close evolutionary ancestry of these groups. However, terrestrial arthropods also convert ammonia to uric acid. This is as opposed to fish, which excrete ammonia directly, without converting it to another substance. However, the conversion of ammonia to uric acid requires more energy and is much more complex than the conversion of ammonia to urea. What do these findings suggest about why these organisms evolved the conversion of ammonia to uric acid?
- to evolve the ability to switch between uric acid and ammonia excretion
- to conserve water to allow them to persist on land
- for reduction in excretion of ammonia
- for excretion of higher concentrations of ammonia
The kidneys are controlled by hormones from the brain, liver, and other locations. However, the kidneys also produce the hormone renin in their juxtaglomerular complex. How would damage to the juxtaglomerular complex affect the renin-angiotensin-aldosterone system?
- Aldosterone will not be produced, decreasing blood volume.
- Angiotensin I will not be produced, decreasing blood pressure.
- Angiotensin-converting enzyme will not be produced, increasing sodium reabsorption.
- Angiotensin II will not be produced, increasing the glomerular filtration rate.
- reduction in urination due to reduction of water reabsorption in the kidneys
- excessive sodium reabsorption by renal tubes due to increase in water reabsorption in the kidneys
- excessive sodium reabsorption by renal tubes due to reduction of water reabsorption in the kidneys
- excessive urination due to reduction of water reabsorption in the kidneys
This diagram was made by a student to illustrate the angiotensin-aldosterone system.
What part of this diagram contains an error?
- ADH is not produced in this system.
- The diagram is missing ANP.
- ACE and renin should be switched.
- ACE and angiotensin should be switched.
This diagram was made by a student to illustrate the angiotensin-aldosterone system.
How would you complete this diagram to make it an accurate model of the renin-angiotensin system?
- Renin acts on angiotensin to directly stimulate the release of aldosterone and ADH.
- Renin acts on angiotensin to form ACE and angiotensin II, which then stimulates the release of aldosterone and ADH.
- Angiotensin II is formed from angiotensin, which is then converted to angiotensin I by ACE. Aldosterone and ADH are then stimulated to be released from angiotensin I.
- Angiotensin I is formed from angiotensin, which is then converted to angiotensin II by ACE. Aldosterone and ADH are then stimulated to be released from angiotensin II.