29
An organism is excreting ions in its urine. What is likely the current tonicity of the organism’s cells, and why?
  1. hypotonicity due to too much solute in its body fluids
  2. hypertonicity due to less solute in its body fluids
  3. hypertonicity due to too much solute in its body fluids
  4. hypotonicity due to less solute in its body fluids
30
A student measures the osmolality of two aqueous solutions, A and B. The student finds that the osmolality of solution B is much higher than solution A. Based on this result, how do solutions A and B likely differ in the concentration of solutes in their solution, and why?
  1. Solution A likely is the more concentrated solution because osmolality measures the moles of solute per kilogram of solute.
  2. Solution B likely is the more concentrated solution because osmolality measures the moles of solute per kilogram of solvent.
  3. Solution A likely is the more concentrated solution because osmolality measures the moles of solute per kilogram of solvent.
  4. Solution B likely is the more concentrated solution because osmolality measures the moles of solute per kilogram of solute.
31
Would an organism that is constantly in a hypertonic environment likely be an osmoregulator or an osmoconformer? Why?
  1. osmoconformer, because it would need to prevent water from leaving its body to remain alive
  2. osmoregulator, because it would need to prevent solutes from leaving its body to remain alive
  3. osmoconformer, because it would need to prevent solutes from leaving its body to remain alive
  4. osmoregulator, because it would need to prevent water from leaving its body to remain alive.
32
Why is excretion important in order to achieve osmotic balance?
  1. The body accumulates water within itself when excretion does not occur, which can have dire consequences.
  2. Excretion regulates the movement of water within the membranes, which ultimately maintains osmotic balance.
  3. In the absence of excretion, there is a shift in the concentrations, which disrupts osmotic balance.
  4. The body builds up many chemical compounds that need to be excreted to maintain homeostasis and osmotic balance.
33
What is the structure of the nephron?
  1. The nephron consists of three parts: the glomerulus, the renal tubule, and the associated capillary network originating from the cortical radiate arteries.
  2. The nephron consists of three parts: the renal corpuscle, the Bowman’s capsule, and the associated capillary network originating from the cortical radiate arteries.
  3. The nephron consists of three parts: the renal corpuscle, the renal tubule, and the associated capillary network originating from the segmental renal artery.
  4. The nephron consists of three parts: the renal corpuscle, the renal tubule, and the associated capillary network originating from the cortical radiate arteries.
34
How does the loop of Henle act as a countercurrent multiplier?
  1. The descending limb of the loop of Henle is water permeable, so the water flows from the filtrate to the interstitial fluid. Osmolality in the limb decreases, and it is lower inside the loop than in the interstitial fluid. As the filtrate enters the ascending limb, Na+ and Cl- ions exit through ion channels present in the cell membrane. Further up, only sodium is passively transported out of the filtrate.
  2. The descending limb of the loop of Henle is water impermeable, so the water flows from the filtrate to the interstitial fluid. Osmolality in the limb increases, and it is higher inside the loop than in the interstitial fluid. As the filtrate enters the ascending limb, Na+ and Cl- ions exit through ion channels present in the cell membrane. Further up, only sodium is passively transported out of the filtrate.
  3. The descending limb of the loop of Henle is water impermeable, so the water flows from the filtrate to the interstitial fluid. Osmolality in the limb increases, and it is higher inside the loop than in the interstitial fluid. As the filtrate enters the ascending limb, Na+ and Cl- ions exit through ion channels present in the cell membrane. Further up, sodium is actively transported out of the filtrate, and chlorine ions follow.
  4. The descending limb of the loop of Henle is water permeable, so the water flows from the filtrate to the interstitial fluid. Osmolality in the limb increases, and it is higher inside the loop than in the interstitial fluid. As the filtrate enters the ascending limb, Na+ and Cl- ions exit through ion channels present in the cell membrane. Further up, sodium is actively transported out of the filtrate, and chlorine ions follows.
35
Why might specialized organs have evolved for excretion of wastes?
  1. Specialized organs have evolved to provide a measure of safety for organisms.
  2. Specialized organs have evolved to distinguish different types of organisms.
  3. Specialized organs have evolved for excretion of wastes to conserve metabolic energy.
  4. Specialized organs have evolved for excretion of wastes so that organisms can survive in adverse conditions.
36
Explain two different excretory systems other than the kidneys.
  1. (1) An excretory mechanism occurs in annelids through the Malpighian tubules. Metabolic wastes like uric acid freely diffuse into the tubules. Uric acid is excreted as a thick paste or powder. (2) An excretory mechanism occurs in the flatworm, which contains two tubules with cells called flame cells. They have cilia that propel waste matter down the tubules and out of the body.
  2. (1) An excretory mechanism occurs in arthropods through a pore called the nephridiopore. These organisms have a system for tubular reabsorption. (2) An excretory mechanism occurs in annelids through the Malpighian tubules. Metabolic wastes like uric acid freely diffuse into the tubules. Uric acid is excreted as a thick paste or powder.
  3. (1) An excretory mechanism is endocytosis, which occurs when vacuoles merge with the cell membrane and excrete cellular wastes in the environment. (2) An excretory mechanism occurs in annelids through a pore called the nephridiopore. These organisms have a system for tubular reabsorption.
  4. (1) An excretory mechanism is exocytosis, which occurs when vacuoles merge with the cell membrane and excrete cellular wastes in the environment. (2) An excretory mechanism occurs in flatworms which consists of two tubules containing cells called flame cells. They have a cluster of cilia that propel waste matter down the tubules and out of the body.
37
How do contractile vacuoles work as excretory systems in microorganisms?
  1. Contractile vacuoles excrete excess water and waste by the process of endocytosis, in which these vacuoles merge with cell membrane and expel wastes into the environment.
  2. Contractile vacuoles excrete uric acid by the process of exocytosis, in which water as well as uric acid is excreted by contraction of a cell when the vacuole merges with the cell membrane.
  3. Contractile vacuoles excrete excess water and uric acid by the process of endocytosis when the vacuole merges with the cell membrane.
  4. Contractile vacuoles excrete excess water and waste by the process of exocytosis, in which the vacuoles merge with the cell membrane and expel wastes into the environment.
38
Describe the urea cycle.
  1. The urea cycle is the mechanism of conversion of urea to ammonia involving five intermediate steps catalyzed by five different enzymes. Of the five steps, the first two occur in the mitochondria and the last three in the cytosol.
  2. The urea cycle is the mechanism of conversion of ammonia to urea involving five intermediate steps catalyzed by five different enzymes. Of the five steps, the first two occur in the mitochondria and the last three in the cytosol.
  3. The urea cycle is the mechanism of conversion of ammonia to urea involving five intermediate steps catalyzed by five different enzymes. Of the five steps, the first two occur in the cytosol and the last three in the mitochondria.
  4. The urea cycle is the mechanism of conversion of ammonia to urea involving five intermediate steps all catalyzed by one enzyme. Of the five steps, the first two occur in the mitochondria and the last three in the cytosol.
39
How are the formation of urea and uric acid similar and different?
  1. In birds, reptiles, and insects, the urea cycle converts ammonia to urea. In mammals, the uric acid cycle converts ammonia to uric acid. Formation of urea from ammonia requires less energy and is less complex than uric acid formation.
  2. In mammals, the urea cycle converts ammonia to urea. In birds, reptiles, and insects, the uric acid cycle converts ammonia to uric acid. Formation of urea from ammonia requires more energy and is less complex than uric acid formation.
  3. In mammals, the urea cycle converts ammonia to urea. In birds, reptiles, and insects, the uric acid cycle converts ammonia to uric acid. Formation of urea from ammonia requires less energy and is more complex than uric acid formation.
  4. In mammals, the urea cycle converts ammonia to urea. In birds, reptiles, and insects, the uric acid cycle converts ammonia to uric acid. Formation of urea from ammonia requires less energy and is less complex than uric acid formation.
40
In terms of evolution, why might the urea cycle have evolved in organisms?
  1. so organisms could adapt to the changing environment when terrestrial life forms evolved
  2. so organisms could evolve the ability to switch between direct ammonia excretion and urea
  3. so organisms could reduce their excretion of ammonia in the form of urea
  4. so organisms could adapt to the changing environment and excrete higher concentrations of uric acid
41
How do hormones regulate blood pressure, blood volume, and kidney function?
  1. Different regions of the liver have specialized cells that respond to chemical messengers and hormones like epinephrine, renin, aldosterone, ADH, and ANP. These regulate the needs of the body and communication between different organ systems.
  2. Different regions of the nephrons have specialized cells that respond to chemical messengers and hormones like epinephrine, renin, aldosterone, ADH, and ANP. These regulate the rate of respiration and communication between the different organ systems.
  3. Different regions of the kidneys have specialized cells that respond to chemical messengers and hormones like epinephrine, renin, aldosterone, ADH, and ANP. These regulate the rate of respiration and communication between the different organ systems.
  4. Different regions of the nephrons have specialized cells that respond to chemical messengers and hormones like epinephrine, renin, aldosterone, ADH, and ANP. These regulate the needs of the body and communication between the different organ systems.
42
How does the renin-angiotensin-aldosterone mechanism function?
  1. Renin, which is secreted by part of the juxtaglomerular complex, acts on angiotensin to form angiotensin I, which is then converted to angiotensin II by ACE. Angiotensin II then stimulates the release of aldosterone and ADH. Angiotensin II acts to destabilize blood pressure and volume.
  2. Renin, which is secreted by part of the juxtaglomerular complex, acts on angiotensin to form angiotensin II, which is then converted to angiotensin I by ACE. Angiotensin II then stimulates the release of aldosterone and ADH. Angiotensin II acts to stabilize blood pressure and volume.
  3. Renin, which is secreted by part of the juxtaglomerular complex, acts on angiotensin to form angiotensin I, which is then converted to angiotensin II and ADH by ACE. ADH then stimulates the release of aldosterone. Angiotensin II acts to stabilize blood pressure and volume.
  4. Renin, which is secreted by part of the juxtaglomerular complex, acts on angiotensin to form angiotensin I, which is then converted to angiotensin II by ACE. Angiotensin II then stimulates the release of aldosterone and ADH. Angiotensin II acts to stabilize blood pressure and volume.
43
What is the “fight or flight” response, and what is its effect on the excretory system?
  1. Aldosterone is the “fight or flight” that is released by the adrenal medulla under extreme stress. This hormone constricts the smooth muscles of the blood vessels. It constricts the afferent arterioles, causing the flow of blood into the nephrons to stop.
  2. Epinephrine and norepinephrine are the “fight or flight” hormones that are released by the adrenal medulla and the nervous system, respectively, under extreme stress. These hormones constrict the smooth muscles of the blood vessels. They constrict the afferent arterioles, causing the flow of blood into the nephrons to stop.
  3. ADH is the “fight or flight” hormone that is released by the adrenal medulla under extreme stress. This hormone constricts the smooth muscles of the blood vessels. It constricts the efferent arterioles, causing the flow of blood into the nephrons to stop.
  4. Epinephrine and norepinephrine are the “fight or flight” hormones that are released by the adrenal medulla and the nervous system, respectively, under extreme stress. These hormones constrict the smooth muscles of the blood vessels. They constrict the efferent arterioles, causing the flow of blood into the nephrons to stop.