AAMC MCAT Exam 4- Bio 2022/2023
Most cytochrome P450 enzymes alter the activity of drugs by:
A.
phosphorylating them.
B.
dephosphorylating them.
C.
oxidizing them.
D.
reducing them. - ANSWER C.
oxidizing them.
cytochrome p450 acts as monooxygenase, where an oxygen atom is inseted into
substrate, thereby resulting in oxidation of substrate.
Given that antibiotics like erythromycin are metabolized by estrogen-sensitive P450
enzymes within the liver, which graph best predicts the expected relative half-life of
erythromycin in adult males versus adult females? - ANSWER A
This is the only graph that correctly illustrates a quicker metabolism—or shorter half-life
—of erythromycin in females. Given the continuous presence of GH in females, the
cytochrome P450 enzymes are up-regulated, resulting in more rapid metabolism of
certain drugs (like erythromycin). As a result, the half-life of erythromycin is expected to
be lower in females (in other words, it would take less time to metabolize the drug due
to the greater presence of P450 enzymes).
The researchers want to generate a mutant mouse strain that expresses a constantly
active variant of ACC2 by replacing the amino acid at position 212 with a different
residue. Which residue is the best choice as a replacement?
A.
Tyrosine
B.
Serine
C.
Alanine
D.
Threonine - ANSWER C.
Alanine
According to the passage, AMPK inactivates ACC2 through phosphorylation of the
residue at position 212. To create a constitutively active variant, the residue at position
212 should be substituted with a residue that cannot be phosphorylated. Of all the
amino acids listed, only alanine cannot be phosphorylated.
Phosphorylation= tyrosine, serine, and threonine
, Bacteriophages were labeled with radioactive phosphorous (32P) and sulfur (35S). The
labeled bacteriophages were then allowed to infect their host cells. At the end of the
experiment, the 32P label was found only inside the host cells and the 35S label was
found only outside the host cells. This experiment shows that:
A.
bacteriophages consist only of DNA and protein.
B.
only DNA, not protein, can enter the host cell.
C.
only protein, not DNA, can enter the host cell.
D.
both DNA and protein can enter the host cell. - ANSWER B.
only DNA, not protein, can enter the host cell.
32P incorporates into DNA
35S incorporates into proteins
if only 32 P is found inside that means only DNA can enter the host cell
Which statement describes ATP consumption and production during the preparatory
and payoff phases of glycolysis, respectively?
A.
Two ATP molecules consumed, four ATP molecules produced
B.
Four ATP molecules consumed, eight ATP molecules produced
C.
Four ATP molecules consumed, two ATP molecules produced
D.
Eight ATP molecules consumed, four ATP molecules produced - ANSWER A.
Two ATP molecules consumed, four ATP molecules produced
2 ATP in and 4 ATP out in glycolysis
As blood passes through actively contracting skeletal muscle tissue, the affinity of
hemoglobin for oxygen in the muscle tissue:
A.
increases as a result of an increase in plasma temperature.
B.
increases as a result of an increase in plasma PO2.
C.
decreases as a result of a decrease in plasma pH.
D.
decreases as a result of a decrease in plasma PCO2. - ANSWER C.
decreases as a result of a decrease in plasma pH.
Most cytochrome P450 enzymes alter the activity of drugs by:
A.
phosphorylating them.
B.
dephosphorylating them.
C.
oxidizing them.
D.
reducing them. - ANSWER C.
oxidizing them.
cytochrome p450 acts as monooxygenase, where an oxygen atom is inseted into
substrate, thereby resulting in oxidation of substrate.
Given that antibiotics like erythromycin are metabolized by estrogen-sensitive P450
enzymes within the liver, which graph best predicts the expected relative half-life of
erythromycin in adult males versus adult females? - ANSWER A
This is the only graph that correctly illustrates a quicker metabolism—or shorter half-life
—of erythromycin in females. Given the continuous presence of GH in females, the
cytochrome P450 enzymes are up-regulated, resulting in more rapid metabolism of
certain drugs (like erythromycin). As a result, the half-life of erythromycin is expected to
be lower in females (in other words, it would take less time to metabolize the drug due
to the greater presence of P450 enzymes).
The researchers want to generate a mutant mouse strain that expresses a constantly
active variant of ACC2 by replacing the amino acid at position 212 with a different
residue. Which residue is the best choice as a replacement?
A.
Tyrosine
B.
Serine
C.
Alanine
D.
Threonine - ANSWER C.
Alanine
According to the passage, AMPK inactivates ACC2 through phosphorylation of the
residue at position 212. To create a constitutively active variant, the residue at position
212 should be substituted with a residue that cannot be phosphorylated. Of all the
amino acids listed, only alanine cannot be phosphorylated.
Phosphorylation= tyrosine, serine, and threonine
, Bacteriophages were labeled with radioactive phosphorous (32P) and sulfur (35S). The
labeled bacteriophages were then allowed to infect their host cells. At the end of the
experiment, the 32P label was found only inside the host cells and the 35S label was
found only outside the host cells. This experiment shows that:
A.
bacteriophages consist only of DNA and protein.
B.
only DNA, not protein, can enter the host cell.
C.
only protein, not DNA, can enter the host cell.
D.
both DNA and protein can enter the host cell. - ANSWER B.
only DNA, not protein, can enter the host cell.
32P incorporates into DNA
35S incorporates into proteins
if only 32 P is found inside that means only DNA can enter the host cell
Which statement describes ATP consumption and production during the preparatory
and payoff phases of glycolysis, respectively?
A.
Two ATP molecules consumed, four ATP molecules produced
B.
Four ATP molecules consumed, eight ATP molecules produced
C.
Four ATP molecules consumed, two ATP molecules produced
D.
Eight ATP molecules consumed, four ATP molecules produced - ANSWER A.
Two ATP molecules consumed, four ATP molecules produced
2 ATP in and 4 ATP out in glycolysis
As blood passes through actively contracting skeletal muscle tissue, the affinity of
hemoglobin for oxygen in the muscle tissue:
A.
increases as a result of an increase in plasma temperature.
B.
increases as a result of an increase in plasma PO2.
C.
decreases as a result of a decrease in plasma pH.
D.
decreases as a result of a decrease in plasma PCO2. - ANSWER C.
decreases as a result of a decrease in plasma pH.
