USABO Practice Questions and Answers
100% Correct
What enzyme does HIV use to convert RNA to DNA? - ANSWER - Reverse Transcriptase
The promoter region of a prokaryotic gene is located ______ to the gene and is the binding site
for ______. - ANSWER - 5'...RNA polymerase
Which of the following is TRUE of prokaryotes?
I. Simultaneous transcription and translation
II. Presence of intron sequences
III. Circular DNA - ANSWER - I and III only
Integral transmembrane proteins are proteins imbedded in the cell membrane. Which of the
following amino acids would you MOST expect to find in the transmembrane region of such
proteins? - ANSWER - Tryptophan
When the base composition of DNA from bacterium Mycobacterium tuberculosis was
determined, 18% of the bases were found to be adenine. What is the G + C content in M.
tuberculosis? - ANSWER - 64%
The frequency of individuals affected with an autosomally recessive inherited disorder is 1 in 4.
Assuming that the population affected by this disease is in Hardy-Weinberg equilibrium, what is
the proportion of carrier individuals in this population? - ANSWER - 50%
In cardiac muscle, calcium ions can move freely between adjacent cells through which of the
following? - ANSWER - gap junctions
Unlike most polypeptide hormones, steroid hormones are unique in that they - ANSWER -
Diffuse across cell membranes
,In superoxide dismutase 1, an enzyme implicated in amyotrophic lateral sclerosis (Lou Gehrig's
disease), a copper ion is bound to the active site and is important for enzyme activity. In this
enzyme, copper most likely functions as a(n) - ANSWER - cofactor
The order of normal blood flow through the human heart is - ANSWER - right atrium, right
ventricle, lungs, left atrium, left ventricle, body
The velocity of action potential conduction across a nerve axon is increased by the presence of
the myelin sheath. In the peripheral nervous system, what cell myelinates the axon? - ANSWER
- schwann cell
The cell bodies of afferent (sensory) nerves involved in somatic reflexes are located in the -
ANSWER - Dorsal root ganglion
Rods and cones are associated with _____ and _____ vision, respectively. - ANSWER -
Light/dark...color
Predation is considered a _________ interaction, while Mutualism is considered a ___________
interaction. - ANSWER - +/-, +/+
Which of the following organisms is INCORRECTLY paired with its trophic level? - ANSWER -
Beetle - secondary consumer
Which of the following is an example of habituation? - ANSWER - Hydra initially contract when
gently touched, but soon stop responding.
Populations that are likely to be living at a density near the limit of their resources, are
characterized as - ANSWER - K-selected
In many types of cancer, the function of the p53 gene is lost. Wild-type p53 is MOST likely to be
a - ANSWER - tumor suppressor
What glycolytic product is shuttled to the mitochondria in aerobic respiration? - ANSWER -
Pyruvate
, During human development, which process leads to the formation of three germ layers? -
ANSWER - gastrulation
Telomerase is responsible for _____ the size of telomeres, and its function is often ____ in
carcinogenesis. - ANSWER - maintaining ... increased
Which of the following is NOT a mode of natural selection? - ANSWER - sexual selection
Protostomes have _____ and _____ types of cleavage. - ANSWER - spiral ... determinate
Which of the following is NOT a characteristic of all chordates? - ANSWER - vertebrae
Allopatric speciation refers to species formed after which type of separation: - ANSWER -
geographic
Which two functional groups are always found in amino acids? - ANSWER - Carboxyl and
amine
Movement of ions across the membrane from higher to lower concentrations through a channel
protein is an example of - ANSWER - Facilitated diffusion
Which group of plants has vascular tissue but does not produce seeds?
I. Mosses
II. Ferns
III. Gymnosperms - ANSWER - II
Which of the following is true for transport in xylem? - ANSWER - Movement through xylem
depends mainly on transpiration
Suppose gene "C" is the gene for color. Its dominant allele has the effect of allowing the
production of fur color while its recessive allele interrupts color production. At another locus,
100% Correct
What enzyme does HIV use to convert RNA to DNA? - ANSWER - Reverse Transcriptase
The promoter region of a prokaryotic gene is located ______ to the gene and is the binding site
for ______. - ANSWER - 5'...RNA polymerase
Which of the following is TRUE of prokaryotes?
I. Simultaneous transcription and translation
II. Presence of intron sequences
III. Circular DNA - ANSWER - I and III only
Integral transmembrane proteins are proteins imbedded in the cell membrane. Which of the
following amino acids would you MOST expect to find in the transmembrane region of such
proteins? - ANSWER - Tryptophan
When the base composition of DNA from bacterium Mycobacterium tuberculosis was
determined, 18% of the bases were found to be adenine. What is the G + C content in M.
tuberculosis? - ANSWER - 64%
The frequency of individuals affected with an autosomally recessive inherited disorder is 1 in 4.
Assuming that the population affected by this disease is in Hardy-Weinberg equilibrium, what is
the proportion of carrier individuals in this population? - ANSWER - 50%
In cardiac muscle, calcium ions can move freely between adjacent cells through which of the
following? - ANSWER - gap junctions
Unlike most polypeptide hormones, steroid hormones are unique in that they - ANSWER -
Diffuse across cell membranes
,In superoxide dismutase 1, an enzyme implicated in amyotrophic lateral sclerosis (Lou Gehrig's
disease), a copper ion is bound to the active site and is important for enzyme activity. In this
enzyme, copper most likely functions as a(n) - ANSWER - cofactor
The order of normal blood flow through the human heart is - ANSWER - right atrium, right
ventricle, lungs, left atrium, left ventricle, body
The velocity of action potential conduction across a nerve axon is increased by the presence of
the myelin sheath. In the peripheral nervous system, what cell myelinates the axon? - ANSWER
- schwann cell
The cell bodies of afferent (sensory) nerves involved in somatic reflexes are located in the -
ANSWER - Dorsal root ganglion
Rods and cones are associated with _____ and _____ vision, respectively. - ANSWER -
Light/dark...color
Predation is considered a _________ interaction, while Mutualism is considered a ___________
interaction. - ANSWER - +/-, +/+
Which of the following organisms is INCORRECTLY paired with its trophic level? - ANSWER -
Beetle - secondary consumer
Which of the following is an example of habituation? - ANSWER - Hydra initially contract when
gently touched, but soon stop responding.
Populations that are likely to be living at a density near the limit of their resources, are
characterized as - ANSWER - K-selected
In many types of cancer, the function of the p53 gene is lost. Wild-type p53 is MOST likely to be
a - ANSWER - tumor suppressor
What glycolytic product is shuttled to the mitochondria in aerobic respiration? - ANSWER -
Pyruvate
, During human development, which process leads to the formation of three germ layers? -
ANSWER - gastrulation
Telomerase is responsible for _____ the size of telomeres, and its function is often ____ in
carcinogenesis. - ANSWER - maintaining ... increased
Which of the following is NOT a mode of natural selection? - ANSWER - sexual selection
Protostomes have _____ and _____ types of cleavage. - ANSWER - spiral ... determinate
Which of the following is NOT a characteristic of all chordates? - ANSWER - vertebrae
Allopatric speciation refers to species formed after which type of separation: - ANSWER -
geographic
Which two functional groups are always found in amino acids? - ANSWER - Carboxyl and
amine
Movement of ions across the membrane from higher to lower concentrations through a channel
protein is an example of - ANSWER - Facilitated diffusion
Which group of plants has vascular tissue but does not produce seeds?
I. Mosses
II. Ferns
III. Gymnosperms - ANSWER - II
Which of the following is true for transport in xylem? - ANSWER - Movement through xylem
depends mainly on transpiration
Suppose gene "C" is the gene for color. Its dominant allele has the effect of allowing the
production of fur color while its recessive allele interrupts color production. At another locus,
