USABO Open Exam 2007
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. - correct answer-D.
golden rice has been engineered to contain higher concentrations of β-carotene than white
rice.
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
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% - correct answer-C. 42%
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 - correct answer-B. Pons
To keep their dog breeds "pure," breeders will keep dogs of different breeds in physically
separate areas when the female is in heat. This aspect of artificial selection is most closely
analogous to which of the following reproductive isolating mechanisms?
A. Mechanical isolation
B. Gametic isolation
C. Cooperative breeding
D. Ecological isolation
, E. Hybrid breakdown - correct answer-D. Ecological isolation
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. - correct 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.
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?
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 - correct answer-B. Ventilation rate increases, arterial PCO2
decreases
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. - correct answer-A. No energy has entered the bottle
from the outside.
Convergent evolution produces ________.
A. analogous structures
B. homologous structures
C. divergent structures
D. both A and C
E. both B and C - correct 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. - correct answer-D.
golden rice has been engineered to contain higher concentrations of β-carotene than white
rice.
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
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% - correct answer-C. 42%
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 - correct answer-B. Pons
To keep their dog breeds "pure," breeders will keep dogs of different breeds in physically
separate areas when the female is in heat. This aspect of artificial selection is most closely
analogous to which of the following reproductive isolating mechanisms?
A. Mechanical isolation
B. Gametic isolation
C. Cooperative breeding
D. Ecological isolation
, E. Hybrid breakdown - correct answer-D. Ecological isolation
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. - correct 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.
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?
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 - correct answer-B. Ventilation rate increases, arterial PCO2
decreases
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. - correct answer-A. No energy has entered the bottle
from the outside.
Convergent evolution produces ________.
A. analogous structures
B. homologous structures
C. divergent structures
D. both A and C
E. both B and C - correct answer-A. analogous structures
