MCAT Test 16 (Princeton Review
Test 1) Questions and Answers
100% Correct
Mercury has a greater density than water, so what can we say about the buoyant
force and the force of surface tension? - ANSWER - The buoyant force and surface
tension are both greater in Mercury
What explains why a water droplet forms a roughly spherical shape if not acted
upon by external forces? - ANSWER - A sphere minimizes the surface area of the
shape for a given volume, which yields the lowest-energy state for the molecules.
Units of surface tension coefficient - ANSWER -
What would happen if an aluminum coin (ρ = 2700 kg/m3, L = 1 cm, V = 1 × 10-8
m3) were gently placed on the surface of water? - ANSWER - -The force of surface
tension by itself would be sufficient to make the coin float.
-The maximum buoyant force for the coin is given by Fb = ρfVsubg, which for the
given situation is Fb = (1000)(10-8)(10) = 10-4 N. The weight of the coin is w = mg
= ρcoinVg = (2700)(10-8)(10) = 2.7 × 10-4 N. The weight is greater than the
buoyant force, so eliminate choice A: the buoyant force alone is not good enough.
The maximum force of surface tension is Fst,y = γL (twice, because the passage
says that there are two of them). This comes out to Ftotal surface tension = (2)
(0.07)(0.01) = 1.4 × 10-3 N. That's greater than the weight, so the surface tension
alone can balance the weight and allow the coin to float.
What explains why F2 is higher than Cl2 in the reactivity series? (what makes F2
more reactive than Cl2) - ANSWER - -F2 has a more negative Δ(SE)° than Cl2
-if the Δ(SE)° is more negative for F2, the overall ΔG° is more negative indicating it is
more energetically favorable to add an electron to F2 compared to Cl2.
What best explains the observed difference in electron affinity between chlorine and
fluorine? - ANSWER - Fluorine has a smaller atomic volume than chlorine, resulting
in stronger repulsive forces between the existing electrons and the electron being
added
,The smaller atomic volume leads to greater repulsive forces between the existing
electrons and the electron being added
A medium with index of refraction n is surrounded by air. The critical angle inside of
the medium is then determined. The medium is then submerged in a fluid with
index of refraction nfluid. If 1 < nfluid < n how is the critical angle affected? -
ANSWER - -It is measured inside of the medium and is greater than its previous
value
-Total internal reflection can only happen when the incident medium has a greater
index of refraction than the surrounding medium. Since the original medium has a
greater index of refraction than the fluid, it must still be the incident medium.
-Snell's law of refraction states that n1sinθ1 = n2sinθ2. For total internal reflection,
θ1 = θcritical and θ2 = 90°, which means that n1sinθcritical = n2. The index of
refraction of air (n2 in this case) is 1, so immersing the medium in fluid has caused
n2 to increase. Since n1 remains constant, the equation tells us that sinθcritical, and
therefore θcritical itself, must increase.
The more negative the H0 of a superacid is means what? - ANSWER - The more
negative, the stronger the acid
What are the three major ways in which antibiotics interact with bacteria? - ANSWER
- -Membrane protein solubilization
-Leakage of cytosolic content
-Detergent fro the cell membrane
If a substrate has a positive charge on it, what kind of amino acid would most likely
be in the active site? - ANSWER - -One with a positive charge like aspartic or
glutamic acid- positive charge means negatively acidic amino acids and vice versa
Why is CH3F unlikely to methylate something? - ANSWER - -Fluorine is a very
unlikely leaving group, so it is unlikely to leave the -CH3 group that it is bonded to
Can KHSO4 and NH4Cl lower the pH of a solution? - ANSWER - Yes, they will
The conjugate acid of a weak base will lower the pH, while the conjugate base of a
weak acid will raise it. Conjugates of strong acids or bases have no effect on pH.
NH4+, the conjugate of the weak base NH3, is acidic.
, K+ and HSO4- are conjugates of a strong base and strong acid, respectively.
Generally this would indicate a neutral salt. However, the HSO4- ion is acidic in its
own right and will lower the pH
A researcher bubbles excess oxygen through a solution containing Ag2S, waits five
minutes, and concludes that no detectable reaction occurred. She leaves the
reaction on her bench overnight, and returns in the morning to find the reaction
complete. What can she conclude from these results? - ANSWER - -The activation
energy barrier for the reaction of Ag2S with O2 is relatively high.
-This question and answer both address kinetics, as the greater the activation
energy, the longer the reaction should proceed
The administration of insulin to a patient with diabetic ketoacidosis will have the
most direct effect on what reaction? - ANSWER - -Breakdown of adipose triglycerides
-the biochemical process which gives rise to diabetic ketoacidosis in the context of
severe insulin deficiency is ketogenesis following the breakdown of triglycerides in
adipose tissue, release of free fatty acids into the blood, and subsequent β-oxidation
of those free fatty acids. Thus the most direct effect of the administration of insulin
would be to reduce the breakdown of adipose triglycerides
What metabolic derangements are most likely to be found in diabetic ketoacidosis? -
ANSWER - -Increased plasma fatty acid concentration
-Decrease in plasma pH
-Due to the lack of insulin, cells will experience a shortage of intracellular glucose
due to a lack of expression of GLUT4 channels which are responsible for transporting
extracellular glucose in to the intracellular compartment
-Lack of insulin leads to increase lipolysis and release of free fatty acids into the
bloodstream
Cerebral edema is the accumulation of fluid in the brain; this condition is most
commonly found in children diagnosed with type 1 diabetes. Clinically-apparent
complications occur in only 1% of cases of childhood DKA, however, when it does
occur, it is associated with high mortality and neurologic morbidity.
Carnitine deficiency is an example of a medical condition affecting the metabolism
of fatty acids. Which of the following would you expect to see in the cells of an
individual with this condition? - ANSWER - Accumulation of fatty acids in the cytosol
and decreased β-oxidation activity
Test 1) Questions and Answers
100% Correct
Mercury has a greater density than water, so what can we say about the buoyant
force and the force of surface tension? - ANSWER - The buoyant force and surface
tension are both greater in Mercury
What explains why a water droplet forms a roughly spherical shape if not acted
upon by external forces? - ANSWER - A sphere minimizes the surface area of the
shape for a given volume, which yields the lowest-energy state for the molecules.
Units of surface tension coefficient - ANSWER -
What would happen if an aluminum coin (ρ = 2700 kg/m3, L = 1 cm, V = 1 × 10-8
m3) were gently placed on the surface of water? - ANSWER - -The force of surface
tension by itself would be sufficient to make the coin float.
-The maximum buoyant force for the coin is given by Fb = ρfVsubg, which for the
given situation is Fb = (1000)(10-8)(10) = 10-4 N. The weight of the coin is w = mg
= ρcoinVg = (2700)(10-8)(10) = 2.7 × 10-4 N. The weight is greater than the
buoyant force, so eliminate choice A: the buoyant force alone is not good enough.
The maximum force of surface tension is Fst,y = γL (twice, because the passage
says that there are two of them). This comes out to Ftotal surface tension = (2)
(0.07)(0.01) = 1.4 × 10-3 N. That's greater than the weight, so the surface tension
alone can balance the weight and allow the coin to float.
What explains why F2 is higher than Cl2 in the reactivity series? (what makes F2
more reactive than Cl2) - ANSWER - -F2 has a more negative Δ(SE)° than Cl2
-if the Δ(SE)° is more negative for F2, the overall ΔG° is more negative indicating it is
more energetically favorable to add an electron to F2 compared to Cl2.
What best explains the observed difference in electron affinity between chlorine and
fluorine? - ANSWER - Fluorine has a smaller atomic volume than chlorine, resulting
in stronger repulsive forces between the existing electrons and the electron being
added
,The smaller atomic volume leads to greater repulsive forces between the existing
electrons and the electron being added
A medium with index of refraction n is surrounded by air. The critical angle inside of
the medium is then determined. The medium is then submerged in a fluid with
index of refraction nfluid. If 1 < nfluid < n how is the critical angle affected? -
ANSWER - -It is measured inside of the medium and is greater than its previous
value
-Total internal reflection can only happen when the incident medium has a greater
index of refraction than the surrounding medium. Since the original medium has a
greater index of refraction than the fluid, it must still be the incident medium.
-Snell's law of refraction states that n1sinθ1 = n2sinθ2. For total internal reflection,
θ1 = θcritical and θ2 = 90°, which means that n1sinθcritical = n2. The index of
refraction of air (n2 in this case) is 1, so immersing the medium in fluid has caused
n2 to increase. Since n1 remains constant, the equation tells us that sinθcritical, and
therefore θcritical itself, must increase.
The more negative the H0 of a superacid is means what? - ANSWER - The more
negative, the stronger the acid
What are the three major ways in which antibiotics interact with bacteria? - ANSWER
- -Membrane protein solubilization
-Leakage of cytosolic content
-Detergent fro the cell membrane
If a substrate has a positive charge on it, what kind of amino acid would most likely
be in the active site? - ANSWER - -One with a positive charge like aspartic or
glutamic acid- positive charge means negatively acidic amino acids and vice versa
Why is CH3F unlikely to methylate something? - ANSWER - -Fluorine is a very
unlikely leaving group, so it is unlikely to leave the -CH3 group that it is bonded to
Can KHSO4 and NH4Cl lower the pH of a solution? - ANSWER - Yes, they will
The conjugate acid of a weak base will lower the pH, while the conjugate base of a
weak acid will raise it. Conjugates of strong acids or bases have no effect on pH.
NH4+, the conjugate of the weak base NH3, is acidic.
, K+ and HSO4- are conjugates of a strong base and strong acid, respectively.
Generally this would indicate a neutral salt. However, the HSO4- ion is acidic in its
own right and will lower the pH
A researcher bubbles excess oxygen through a solution containing Ag2S, waits five
minutes, and concludes that no detectable reaction occurred. She leaves the
reaction on her bench overnight, and returns in the morning to find the reaction
complete. What can she conclude from these results? - ANSWER - -The activation
energy barrier for the reaction of Ag2S with O2 is relatively high.
-This question and answer both address kinetics, as the greater the activation
energy, the longer the reaction should proceed
The administration of insulin to a patient with diabetic ketoacidosis will have the
most direct effect on what reaction? - ANSWER - -Breakdown of adipose triglycerides
-the biochemical process which gives rise to diabetic ketoacidosis in the context of
severe insulin deficiency is ketogenesis following the breakdown of triglycerides in
adipose tissue, release of free fatty acids into the blood, and subsequent β-oxidation
of those free fatty acids. Thus the most direct effect of the administration of insulin
would be to reduce the breakdown of adipose triglycerides
What metabolic derangements are most likely to be found in diabetic ketoacidosis? -
ANSWER - -Increased plasma fatty acid concentration
-Decrease in plasma pH
-Due to the lack of insulin, cells will experience a shortage of intracellular glucose
due to a lack of expression of GLUT4 channels which are responsible for transporting
extracellular glucose in to the intracellular compartment
-Lack of insulin leads to increase lipolysis and release of free fatty acids into the
bloodstream
Cerebral edema is the accumulation of fluid in the brain; this condition is most
commonly found in children diagnosed with type 1 diabetes. Clinically-apparent
complications occur in only 1% of cases of childhood DKA, however, when it does
occur, it is associated with high mortality and neurologic morbidity.
Carnitine deficiency is an example of a medical condition affecting the metabolism
of fatty acids. Which of the following would you expect to see in the cells of an
individual with this condition? - ANSWER - Accumulation of fatty acids in the cytosol
and decreased β-oxidation activity
