USABO Open Exam 2025/2026 Exam
Questions and Correct Answers | New
Update
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.
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,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% - 🧠 ANSWER ✔✔C. 42%
An individual suffers brain damage that results in respiratory failure. Which
region of the brain was most likely damaged?
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PRIVACY STATEMENT. ALL RIGHTS RESERVED
, A. Substantia nigra
B. Pons
C. Red nucleus
D. Superior colliculus
E. Reticular formation - 🧠 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 - 🧠 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
COPYRIGHT©PROFFKERRYMARTIN 2025/2026. YEAR PUBLISHED 2025. COMPANY REGISTRATION NUMBER: 619652435. TERMS OF USE.
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PRIVACY STATEMENT. ALL RIGHTS RESERVED
Questions and Correct Answers | New
Update
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.
COPYRIGHT©PROFFKERRYMARTIN 2025/2026. YEAR PUBLISHED 2025. COMPANY REGISTRATION NUMBER: 619652435. TERMS OF USE.
1
PRIVACY STATEMENT. ALL RIGHTS RESERVED
,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% - 🧠 ANSWER ✔✔C. 42%
An individual suffers brain damage that results in respiratory failure. Which
region of the brain was most likely damaged?
COPYRIGHT©PROFFKERRYMARTIN 2025/2026. YEAR PUBLISHED 2025. COMPANY REGISTRATION NUMBER: 619652435. TERMS OF USE.
2
PRIVACY STATEMENT. ALL RIGHTS RESERVED
, A. Substantia nigra
B. Pons
C. Red nucleus
D. Superior colliculus
E. Reticular formation - 🧠 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 - 🧠 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
COPYRIGHT©PROFFKERRYMARTIN 2025/2026. YEAR PUBLISHED 2025. COMPANY REGISTRATION NUMBER: 619652435. TERMS OF USE.
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PRIVACY STATEMENT. ALL RIGHTS RESERVED
