Page 1 of 226
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QUESTION: A man and a woman get married and soon learn that they both have a rare,
genetically inherited recessive disorder that makes them prone to dizziness. Worried about the
fate of their children, they seek the advice of a genetic counselor. She sequences their genomes
and assures them that none of their children will have the disorder. What information would
she have to obtain from the sequencing procedure that allows her to make this claim?
A. The dizziness phenotype in the man is due to a mutation in a gene other than the gene
responsible for the woman's phenotype.
B. The dizziness disorder is an autosomal recessive trait.
C. The man and the woman are related genetically causing the same dizziness phenotype.
D. The dizziness disorder is linked to the sex chromosomes.
E. It is impossible for the man and the woman to have unaffected children - the genetic
counselor is wrong. - ANSWER-A. The dizziness phenotype in the man is due to a mutation in a
gene other than the gene responsible for the woman's phenotype.
QUESTION: An animal experiences an acid-base imbalance in the arterial blood that results in
acidosis. To increase pH toward normal, which direction would the ventilation rate be changed
and what would be the corresponding change in arterial PCO2?
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A. Ventilation rate increases, arterial PCO2 increases
B. Ventilation rate increases, arterial PCO2 decreases
C. Ventilation rate decreases, arterial PCO2 increases
D. Ventilation rate decreases, arterial PCO2 decreases
E. None of the above - ANSWER-B. Ventilation rate increases, arterial PCO2 decreases
QUESTION: Plants, animals and a quantity of air were sealed into a large glass bottle to
comprise a balanced aquarium. After three months, the plants and animals in the aquarium
appear to be alive and healthy. Which of the following statements is scientifically
UNACCEPTABLE?
A. No energy has entered the bottle from the outside.
B. Potential energy in one organism has entered another organism.
C. Some atoms from water molecules have become part of organic compounds.
D. The air above the water contains CO2.
E. During the three months, the average biomass of plant matter was greater than the average
biomass of animal matter. - ANSWER-A. No energy has entered the bottle from the outside.
QUESTION: Convergent evolution produces ________.
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A. analogous structures
B. homologous structures
C. divergent structures
D. both A and C
E. both B and C - ANSWER-A. analogous structures
The production of the genetically engineered "golden rice" could be important to people of
developing nations, especially in South-East Asia, because:
A. people are more likely to consume yellow grains than white.
B. golden rice is less expensive to grow and harvest than white rice.
C. golden rice has been engineered to be resistant to most commercially available herbicides.
D. golden rice has been engineered to contain higher concentrations of β-carotene than white
rice.
E. golden rice has been engineered to produce biodegradable plastics. - ANSWER-D. golden rice
has been engineered to contain higher concentrations of β-carotene than white rice.
QUESTION: A large population of laboratory rats was allowed to breed randomly for a number
of generations. In this population, agouti fur is encoded by the A allele and is dominant to the
black fur trait encoded by the a allele. At the beginning of the breeding cycles, 49% of the rats
had black fur. At the end of the breeding cycles, this percentage was the same. The rest of the
animals had agouti fur. The heterozygotes with agouti fur were indistinguishable from
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homozygotes with agouti fur. What percentage of this population is probably heterozygous for
the fur color trait assuming the rats are following Hardy-Weinberg population genetics?
A. 7%
B. 30%
C. 42%
D. 49%
E. 70% - ANSWER-C. 42%
QUESTION: An individual suffers brain damage that results in respiratory failure. Which region
of the brain was most likely damaged?
A. Substantia nigra
B. Pons
C. Red nucleus
D. Superior colliculus
E. Reticular formation - ANSWER-B. Pons
4
USABO OPEN EXAM ACTUAL EXAM TEST BANK WITH
600+ QUESTIONS AND DETAILED SOLUTIONS LATEST
UPDATE THIS YEAR
QUESTION: A man and a woman get married and soon learn that they both have a rare,
genetically inherited recessive disorder that makes them prone to dizziness. Worried about the
fate of their children, they seek the advice of a genetic counselor. She sequences their genomes
and assures them that none of their children will have the disorder. What information would
she have to obtain from the sequencing procedure that allows her to make this claim?
A. The dizziness phenotype in the man is due to a mutation in a gene other than the gene
responsible for the woman's phenotype.
B. The dizziness disorder is an autosomal recessive trait.
C. The man and the woman are related genetically causing the same dizziness phenotype.
D. The dizziness disorder is linked to the sex chromosomes.
E. It is impossible for the man and the woman to have unaffected children - the genetic
counselor is wrong. - ANSWER-A. The dizziness phenotype in the man is due to a mutation in a
gene other than the gene responsible for the woman's phenotype.
QUESTION: An animal experiences an acid-base imbalance in the arterial blood that results in
acidosis. To increase pH toward normal, which direction would the ventilation rate be changed
and what would be the corresponding change in arterial PCO2?
1
,Page 2 of 226
A. Ventilation rate increases, arterial PCO2 increases
B. Ventilation rate increases, arterial PCO2 decreases
C. Ventilation rate decreases, arterial PCO2 increases
D. Ventilation rate decreases, arterial PCO2 decreases
E. None of the above - ANSWER-B. Ventilation rate increases, arterial PCO2 decreases
QUESTION: Plants, animals and a quantity of air were sealed into a large glass bottle to
comprise a balanced aquarium. After three months, the plants and animals in the aquarium
appear to be alive and healthy. Which of the following statements is scientifically
UNACCEPTABLE?
A. No energy has entered the bottle from the outside.
B. Potential energy in one organism has entered another organism.
C. Some atoms from water molecules have become part of organic compounds.
D. The air above the water contains CO2.
E. During the three months, the average biomass of plant matter was greater than the average
biomass of animal matter. - ANSWER-A. No energy has entered the bottle from the outside.
QUESTION: Convergent evolution produces ________.
2
,Page 3 of 226
A. analogous structures
B. homologous structures
C. divergent structures
D. both A and C
E. both B and C - ANSWER-A. analogous structures
The production of the genetically engineered "golden rice" could be important to people of
developing nations, especially in South-East Asia, because:
A. people are more likely to consume yellow grains than white.
B. golden rice is less expensive to grow and harvest than white rice.
C. golden rice has been engineered to be resistant to most commercially available herbicides.
D. golden rice has been engineered to contain higher concentrations of β-carotene than white
rice.
E. golden rice has been engineered to produce biodegradable plastics. - ANSWER-D. golden rice
has been engineered to contain higher concentrations of β-carotene than white rice.
QUESTION: A large population of laboratory rats was allowed to breed randomly for a number
of generations. In this population, agouti fur is encoded by the A allele and is dominant to the
black fur trait encoded by the a allele. At the beginning of the breeding cycles, 49% of the rats
had black fur. At the end of the breeding cycles, this percentage was the same. The rest of the
animals had agouti fur. The heterozygotes with agouti fur were indistinguishable from
3
, Page 4 of 226
homozygotes with agouti fur. What percentage of this population is probably heterozygous for
the fur color trait assuming the rats are following Hardy-Weinberg population genetics?
A. 7%
B. 30%
C. 42%
D. 49%
E. 70% - ANSWER-C. 42%
QUESTION: An individual suffers brain damage that results in respiratory failure. Which region
of the brain was most likely damaged?
A. Substantia nigra
B. Pons
C. Red nucleus
D. Superior colliculus
E. Reticular formation - ANSWER-B. Pons
4
