USABO Open Exam Questions with
Complete Solutions
In certain areas of Sub-Saharan Africa high levels of anemia
are exhibited as a consequence of iron deficiency. What other
symptom would you expect might be found in these peoples?
A. goiter
B. decrease in immune function
C. high degree of oscillation in blood glucose levels
D. scurvy
E. reproductive failure - Correct Answers ✅B. decrease in
immune function
Inflammation and injury of the pancreas can cause elevated
levels of serum amylase. Injury or disease of which of the
following organs might you expect to produce a similar
laboratory finding?
A. Liver
B. Colon
C. Thyroid
D. Salivary gland
E. Adrenal gland - Correct Answers ✅D. Salivary gland
What process in plants requires darkness?
,USABO Open Exam Questions with
Complete Solutions
A. the light-independent reactions
B. the light-dependent reactions
C. coordination of protein synthesis
D. coordination of hormone synthesis
E. both C and D - Correct Answers ✅E. both C and D
The fluidity of a lipid bilayer is enhanced with:
A. decreased temperature.
B. increased unsaturation in fatty acid tails.
C. increased unsaturation in polar head groups.
D. increased saturation in fatty acid tails.
E. increased fatty acid chain length. - Correct Answers ✅B.
increased unsaturation in fatty acid tails.
An inbred strain of plants has a mean height of 24 cm. A
second strain of the same species also has a mean height of
24 cm. When these plants are crossed, the F1 are also 24 cm
in height. However, when the F1 plants are crossed, the F2
plants show a wide range of heights; the greatest number are
similar to the P1 and F1, but approximately 4 of 1000 are only
12 cm tall and 4 of 1000 are 40 cm tall. What fraction of the
F2 plants will be approximately 28 cm in height? [Assume
that each of the alleles involved in determining increase in
plant height contributes the same amount.]
, USABO Open Exam Questions with
Complete Solutions
A. 314
B. 9/16
C. 56/256
D. None
E. Cannot be determined from the information given. -
Correct Answers ✅C. 56/256
The skin forming the flying surface in the wing of a bat and
the feathers forming the flying surface in the wing of a bird:
A. evolved from a similar structure in a common ancestor.
B. are different because of adaptive radiation.
C. do not develop from the same sources in the embryos of
bat and bird, and are analogous.
D. perform different functions in the bat and the bird.
E. evolved in response to "felt need" in adult birds and bats. -
Correct Answers ✅C. do not develop from the same
sources in the embryos of bat and bird, and are analogous.
Your parents built a tree house for you when you were 8 years
old and 4 feet tall. They placed the tree house on a branch of
a tree that was 5 feet above the ground in a tree that was 20
feet tall. You are now 17 years old and 6 feet tall. The tree
Complete Solutions
In certain areas of Sub-Saharan Africa high levels of anemia
are exhibited as a consequence of iron deficiency. What other
symptom would you expect might be found in these peoples?
A. goiter
B. decrease in immune function
C. high degree of oscillation in blood glucose levels
D. scurvy
E. reproductive failure - Correct Answers ✅B. decrease in
immune function
Inflammation and injury of the pancreas can cause elevated
levels of serum amylase. Injury or disease of which of the
following organs might you expect to produce a similar
laboratory finding?
A. Liver
B. Colon
C. Thyroid
D. Salivary gland
E. Adrenal gland - Correct Answers ✅D. Salivary gland
What process in plants requires darkness?
,USABO Open Exam Questions with
Complete Solutions
A. the light-independent reactions
B. the light-dependent reactions
C. coordination of protein synthesis
D. coordination of hormone synthesis
E. both C and D - Correct Answers ✅E. both C and D
The fluidity of a lipid bilayer is enhanced with:
A. decreased temperature.
B. increased unsaturation in fatty acid tails.
C. increased unsaturation in polar head groups.
D. increased saturation in fatty acid tails.
E. increased fatty acid chain length. - Correct Answers ✅B.
increased unsaturation in fatty acid tails.
An inbred strain of plants has a mean height of 24 cm. A
second strain of the same species also has a mean height of
24 cm. When these plants are crossed, the F1 are also 24 cm
in height. However, when the F1 plants are crossed, the F2
plants show a wide range of heights; the greatest number are
similar to the P1 and F1, but approximately 4 of 1000 are only
12 cm tall and 4 of 1000 are 40 cm tall. What fraction of the
F2 plants will be approximately 28 cm in height? [Assume
that each of the alleles involved in determining increase in
plant height contributes the same amount.]
, USABO Open Exam Questions with
Complete Solutions
A. 314
B. 9/16
C. 56/256
D. None
E. Cannot be determined from the information given. -
Correct Answers ✅C. 56/256
The skin forming the flying surface in the wing of a bat and
the feathers forming the flying surface in the wing of a bird:
A. evolved from a similar structure in a common ancestor.
B. are different because of adaptive radiation.
C. do not develop from the same sources in the embryos of
bat and bird, and are analogous.
D. perform different functions in the bat and the bird.
E. evolved in response to "felt need" in adult birds and bats. -
Correct Answers ✅C. do not develop from the same
sources in the embryos of bat and bird, and are analogous.
Your parents built a tree house for you when you were 8 years
old and 4 feet tall. They placed the tree house on a branch of
a tree that was 5 feet above the ground in a tree that was 20
feet tall. You are now 17 years old and 6 feet tall. The tree
