USABO OPEN EXAM TEST PAPER 2026
QUESTIONS WITH SOLUTIONS GRADED A+
⩥ 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%
,⩥ 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
⩥ 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
⩥ 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
⩥ 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
⩥ Predation is considered a _________ interaction, while Mutualism is
considered a ___________ interaction. Answer: +/-, +/+
QUESTIONS WITH SOLUTIONS GRADED A+
⩥ 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%
,⩥ 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
⩥ 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
⩥ 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
⩥ 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
⩥ Predation is considered a _________ interaction, while Mutualism is
considered a ___________ interaction. Answer: +/-, +/+
