USABO PRACTICE
EXAM QUESTIONS
AND ANSWERS
What enzyme does HIV use to convert RNA to DNA? - Answers-Reverse Transcriptase
The promoter region of a prokaryotic gene is located ______ to the gene and is the
binding site for ______. - Answers-5'...RNA polymerase
Which of the following is TRUE of prokaryotes?
I. Simultaneous transcription and translation
II. Presence of intron sequences
III. Circular DNA - Answers-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? - Answers-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? - Answers-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? - Answers-
50%
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? - Answers-schwann cell
,The cell bodies of afferent (sensory) nerves involved in somatic reflexes are located in
the - Answers-Dorsal root ganglion
Rods and cones are associated with _____ and _____ vision, respectively. - Answers-
Light/dark...color
Populations that are likely to be living at a density near the limit of their resources, are
characterized as - Answers-K-selected
In many types of cancer, the function of the p53 gene is lost. Wild-type p53 is MOST
likely to be a - Answers-tumor suppressor
What glycolytic product is shuttled to the mitochondria in aerobic respiration? - Answers-
Pyruvate
During human development, which process leads to the formation of three germ layers?
- Answers-gastrulation
Telomerase is responsible for _____ the size of telomeres, and its function is often ____
in carcinogenesis. - Answers-maintaining ... increased
Which of the following is NOT a mode of natural selection? - Answers-sexual selection
Protostomes have _____ and _____ types of cleavage. - Answers-spiral ... determinate
Which of the following is NOT a characteristic of all chordates? - Answers-vertebrae
In cardiac muscle, calcium ions can move freely between adjacent cells through which
of the following? - Answers-gap junctions
Unlike most polypeptide hormones, steroid hormones are unique in that they - Answers-
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) - Answers-cofactor
The order of normal blood flow through the human heart is - Answers-right atrium, right
ventricle, lungs, left atrium, left ventricle, body
Allopatric speciation refers to species formed after which type of separation: - Answers-
geographic
Which two functional groups are always found in amino acids? - Answers-Carboxyl and
amine
, Movement of ions across the membrane from higher to lower concentrations through a
channel protein is an example of - Answers-Facilitated diffusion
Which group of plants has vascular tissue but does not produce seeds?
I. Mosses
II. Ferns
III. Gymnosperms - Answers-II
Which of the following is true for transport in xylem? - Answers-Movement through
xylem depends mainly on transpiration
Predation is considered a _________ interaction, while Mutualism is considered a
___________ interaction. - Answers-+/-, +/+
Which of the following organisms is INCORRECTLY paired with its trophic level? -
Answers-Beetle - secondary consumer
Which of the following is an example of habituation? - Answers-Hydra initially contract
when gently touched, but soon stop responding.
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, there exists another gene that influences color, at which black (B) is dominant to
brown (b). What is the relationship between these genes called? - Answers-Epistatic
During migrations, some birds use which of the following as reference frameworks?
I. The sun
II. Constellations
III. Earth's magnetic field - Answers-I,II, and III
Generally, there are more species per square kilometer in which of the following types
of ecosystem? - Answers-Coral reef
RUBP is used and PGA is formed in: - Answers-dark reaction (Calvin cycle) of
photosynthesis
Which is TRUE of the dark reaction (Calvin cycle) of photosynthesis? - Answers-It uses
carbon dioxide
In the fern life cycle, the dominant generation is the: - Answers-diploid sporophyte
Assume a person is placed on cortisol medication, a glucocorticoid. How would you
expect the rates of ACTH and CRF hormone production to change in the person? -
Answers-ACTH production would decrease, CRF production would increase
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