REA MCAT Multiple Choice Q's
with All Correct Answers
Enzymes are:
a. proteins
b. catalysts
c. carbohydrates
d. both proteins and catalysts - ANSWER - D. Enzymes are proteins that act as
catalysts. Carbohydrates are not proteins, and therefore cannot be enzymes.
Organisms can control all of the following EXCEPT:
a. location of enzymes
b. type of enzymes
c. amount of enzymes
d. activity of enzymes - ANSWER - B. Organisms control the activity of enzymes by
changing or blocking active sites. Location and amount of enzymes may be
controlled through feedback. Types of enzymes are determined genetically and
cannot be altered.
In feedback inhibition of metabolic pathways, which are controlled directly?
a. end pdts
b. metabolites
c. enzymes
d. precursor molecules - ANSWER - C. In feedback inhibition the flow of metabolites
is often regulated by controlling the activity of key enzymes in a pathway. Usually,
the first enzyme in a metabolic pathway is controlled by the end product of the
pathway.
Which of the following structures is found in a bacterial cell?
a. Golgi apparatus
b. Nuclear membrane
c. ribosomes
,d. Mitochondrion - ANSWER - C. Unlike eukaryotes, bacterial cells lack Golgi
apparatus, endoplasmic reticulum, mitochondria and a nuclear membrane. The lack
of an endoplasmic reticulum means that the ribosomes are free.
In transduction, a:
a. male chromosome is injected into a female cell
b. female chromosome is injected into a male cell
c. bacteriophage transfers genetic material between bacteria
d. DNA fragment from a donor strain is directly taken up by a recipient strain of
bacteria - ANSWER - C. A refers to bacterial conjugation; B is an impossibility; D
refers to transformation.
Glycolysis does NOT:
a. occur in the cytoplasm
b. require oxygen
c. produce ATP
d. break down glucose - ANSWER - B. Glycolysis is the series of metabolic reactions
by which glucose is converted to pyruvate (a 3-C sugar) with the concurrent
formation of ATP. Glycolysis occurs in the cytoplasm of the cell and for this process
the presence of oxygen is unnecessary.
In the Krebs Cycle, all of the following occur EXCEPT:
a. oxidation of succinate
b. formation of FADH2
c. formation of NADH
d. transformation of NADH to NAD - ANSWER - D. NADH is converted to NAD during
oxidative phosphorylation, which yields 3 ATP.
The ratio of ATP produced aerobically to anaerobically by the oxidation of one
molecule of glucose is
a. 2:1
b. 1:2
c. 1:18
, d. 18:1 - ANSWER - D. The aerobic production of ATP involves the Krebs cycle and
the oxidation of glucose. The anaerobic production of ATP takes place during
glycolysis. The citric acid cycle produces 34 ATP's and the oxidation of glucose
produces 2. This makes the total number of ATP's produced during aerobic
processes 36. Glycolysis yields 2 ATP's. The net ratio of aerobic ATP to anaerobic
ATP is 36:2, which reduces to 18:1.
Nitrous acid converts cytosine to uracil by deamination. This type of conversion in
one DNA strand would lead to a change in the complementary base in the other
strand to
a. adenine
b. cytosine
c. thymine
d. guanine - ANSWER - A. Cytosine normally binds to guanine and uracil normally
binds to adenine. A conversion of cytosine to uracil would lead to a conversion of
guanine to adenine in the complementary strand. Thus a CG to AU event has
occurred.
Viruses differ from living organisms because
a. viruses possess no bounding membrane
b. viruses lack all metabolic machinery
c. viruses lack all reproductive machinery
d. all of the above - ANSWER - D. Viruses do not have any membranes because they
have no need to take in or expel material. Viruses lack all metabolic machinery and
do not produce ATP because they do not perform energy requiring processes.
Viruses do possess either DNA or RNA, but cannot independently reproduce. They
must rely on host cells for reproductive machinery and components.
Moderate viruses may
a. replace DNA only when the host replicates
b. induce tumors
c. cause immediate lysis of infected bacteria
d. have both DNA and RNA - ANSWER - A. In moderate viruses the phage DNA is
incorporated directly into the host chromosome, and thus replicates only when the
host does. RNA retroviruses may induce tumors. Most viruses, with the exception of
with All Correct Answers
Enzymes are:
a. proteins
b. catalysts
c. carbohydrates
d. both proteins and catalysts - ANSWER - D. Enzymes are proteins that act as
catalysts. Carbohydrates are not proteins, and therefore cannot be enzymes.
Organisms can control all of the following EXCEPT:
a. location of enzymes
b. type of enzymes
c. amount of enzymes
d. activity of enzymes - ANSWER - B. Organisms control the activity of enzymes by
changing or blocking active sites. Location and amount of enzymes may be
controlled through feedback. Types of enzymes are determined genetically and
cannot be altered.
In feedback inhibition of metabolic pathways, which are controlled directly?
a. end pdts
b. metabolites
c. enzymes
d. precursor molecules - ANSWER - C. In feedback inhibition the flow of metabolites
is often regulated by controlling the activity of key enzymes in a pathway. Usually,
the first enzyme in a metabolic pathway is controlled by the end product of the
pathway.
Which of the following structures is found in a bacterial cell?
a. Golgi apparatus
b. Nuclear membrane
c. ribosomes
,d. Mitochondrion - ANSWER - C. Unlike eukaryotes, bacterial cells lack Golgi
apparatus, endoplasmic reticulum, mitochondria and a nuclear membrane. The lack
of an endoplasmic reticulum means that the ribosomes are free.
In transduction, a:
a. male chromosome is injected into a female cell
b. female chromosome is injected into a male cell
c. bacteriophage transfers genetic material between bacteria
d. DNA fragment from a donor strain is directly taken up by a recipient strain of
bacteria - ANSWER - C. A refers to bacterial conjugation; B is an impossibility; D
refers to transformation.
Glycolysis does NOT:
a. occur in the cytoplasm
b. require oxygen
c. produce ATP
d. break down glucose - ANSWER - B. Glycolysis is the series of metabolic reactions
by which glucose is converted to pyruvate (a 3-C sugar) with the concurrent
formation of ATP. Glycolysis occurs in the cytoplasm of the cell and for this process
the presence of oxygen is unnecessary.
In the Krebs Cycle, all of the following occur EXCEPT:
a. oxidation of succinate
b. formation of FADH2
c. formation of NADH
d. transformation of NADH to NAD - ANSWER - D. NADH is converted to NAD during
oxidative phosphorylation, which yields 3 ATP.
The ratio of ATP produced aerobically to anaerobically by the oxidation of one
molecule of glucose is
a. 2:1
b. 1:2
c. 1:18
, d. 18:1 - ANSWER - D. The aerobic production of ATP involves the Krebs cycle and
the oxidation of glucose. The anaerobic production of ATP takes place during
glycolysis. The citric acid cycle produces 34 ATP's and the oxidation of glucose
produces 2. This makes the total number of ATP's produced during aerobic
processes 36. Glycolysis yields 2 ATP's. The net ratio of aerobic ATP to anaerobic
ATP is 36:2, which reduces to 18:1.
Nitrous acid converts cytosine to uracil by deamination. This type of conversion in
one DNA strand would lead to a change in the complementary base in the other
strand to
a. adenine
b. cytosine
c. thymine
d. guanine - ANSWER - A. Cytosine normally binds to guanine and uracil normally
binds to adenine. A conversion of cytosine to uracil would lead to a conversion of
guanine to adenine in the complementary strand. Thus a CG to AU event has
occurred.
Viruses differ from living organisms because
a. viruses possess no bounding membrane
b. viruses lack all metabolic machinery
c. viruses lack all reproductive machinery
d. all of the above - ANSWER - D. Viruses do not have any membranes because they
have no need to take in or expel material. Viruses lack all metabolic machinery and
do not produce ATP because they do not perform energy requiring processes.
Viruses do possess either DNA or RNA, but cannot independently reproduce. They
must rely on host cells for reproductive machinery and components.
Moderate viruses may
a. replace DNA only when the host replicates
b. induce tumors
c. cause immediate lysis of infected bacteria
d. have both DNA and RNA - ANSWER - A. In moderate viruses the phage DNA is
incorporated directly into the host chromosome, and thus replicates only when the
host does. RNA retroviruses may induce tumors. Most viruses, with the exception of
