Biology for AP® Courses

# Critical Thinking Questions

Biology for AP® CoursesCritical Thinking Questions

29 .

This image shows a U-shaped tube with a semi-permeable membrane separating it into two. The membrane allows small molecules to pass through, but not larger molecules.

Sugar, a large molecule, is added to left arm of the U-shaped tube. Make a claim about what will happen next.

1. The water level will increase equally in both arms because of the added volume of the sugar.
2. The water level will increase slightly on the left arm because of the added volume of the sugar.
3. The water level will increase considerably on the left arm because of the added volume of the sugar, as well as more water going to left arm due to osmotic pressure.
4. The water level will increase slightly on the right arm because water going to right arm due to osmotic pressure.
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 .

This graph shows the results of an experiment on some rabbits. The rabbits were injected by increasing amounts of epinephrine, shown in the x-axis. The y-axis shows the heart rate of the rabbit.

What is the independent variable in this experiment?

1. The concentration of epinephrine injected to the rabbits.
2. The heart rate of the rabbits.
3. The time it takes for the injections to be effective.
4. The number of rabbits used in the experiment.
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 .

This graph shows the results of an experiment on some rabbits. The rabbits were injected by increasing amounts of epinephrine, shown in the x-axis. The y-axis shows the heart rate of the rabbit.

What is a claim that can be done from this graph?

1. Even very small amounts of epinephrine trigger a big response.
2. Epinephrine does not have a lot of effect until its concentration reaches a threshold.
3. There is no upper limit to the effect of epinephrine.
4. Increasing epinephrine decreases the rate of the heart beat.
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