USABO Practice EXAM QUESTIONS
WITH CORRECT SOLUTIONS||100%
GUARANTEED PASS|| A+
GRADED||UPDATED 2025/2026
SYLLABUS||<<NEWEST VERSION>>
A red pigment is extracted from a marine alga. Which best supports the hypothesis
that the pigment is involved in photosynthesis? The red pigment: - ANSWER ✓
has an absorption spectrum similar to the photosynthetic action spectrum for that
same marine alga
Given the following pedigree: What is (are) the possible mode(s) of inheritance? I.
Autosomal dominant II. Autosomal recessive III. X-linked dominant IV. X-linked
recessive (question 25 of 2005 exam) - ANSWER ✓ II or IV only
Color-blindness is a recessive, X-linked trait. A couple, who are both blood type A
and who both have normal vision, have a son who is blood type O and colorblind.
What is the probability that their next child will be a daughter who is blood type O
and has normal vision? - ANSWER ✓ 1/8
A strain of bacteria living in a hospital is found to have a plasmid containing two
genes: one for sex pilus construction, and one for tetracycline resistance. If these
bacteria were to undergo conjugation with bacteria lacking this plasmid, and thus
transferred the plasmid to the other bacteria, the most likely result would be: -
ANSWER ✓ rapid spread of tetracycline resistance to other bacteria in the hospital
How do Aspirin and Ibuprofen produce anti-inflammatory effects? - ANSWER ✓
by inhibiting prostaglandin synthesis
Group hunting can favorably influence the ability to obtain different food
resources and the efficiency of a capture as a result of: - ANSWER ✓ increased
chance of capturing larger prey
, A fruit with an endocarp composed of sclerenchyma cells, but fleshy mesocarp
and exocarp, is called a: - ANSWER ✓ drupe
Most of today's biological diversity has arisen via: - ANSWER ✓ cladogenesis
Which of the following would act as an "uncoupler" of electron transport and ATP
synthesis in the mitochondrion? - ANSWER ✓ A and C only (dinitrophenol and
the F0 base piece of the ATP synthase (without the F1 subunit))
Concentration of urine is essential to the survival of many vertebrates. Which
class of vertebrates would you expect does not use this mechanism for
homeostasis? - ANSWER ✓ Osteichthyes
A comparison of the energy expenditures (kcal/kg/day) for a penguin and for a
python (assuming they are of equal size) would show that: - ANSWER ✓ the
energy expenditure of the penguin is greater than that for the python
Which of the following is the least dependable method for determining the adaxial
surface of a leaf? - ANSWER ✓ the distribution of stomata
What is the probability of obtaining the given genotype in the offspring,
AAbbCCdd, from the parents AaBbCcDd x AABbCcDd (assume independent
assortment of all gene pairs)? - ANSWER ✓ 1/128
Which of the following statements is NOT characteristic of polygyny? -
ANSWER ✓ Females compete for 'status' in communal displays (leks) and males
choose among females
The inner surface of the urethra, the tube through which urine exits the body, is
lined with which type of epithelial cells? - ANSWER ✓ stratified columnar
epithelia
Which of the following are characteristics of both bacteria and fungi? - ANSWER
✓ cell wall, DNA, and plasma membrane
Net primary productivity, in most ecosystems, is important because it represents
the: - ANSWER ✓ storage of chemical energy that would be available to
heterotrophs
, In general, where are the vessels found in "ring porous wood?" - ANSWER ✓ in
the spring wood
Terminally differentiated cells are most often found in which phase of the cell
cycle? - ANSWER ✓ G0
During the first 6 to 8 weeks of gestation, the principal source of estrogen and
progesterone is: - ANSWER ✓ corpus luteum
There is evidence that anadromous migration - from ocean to headwaters of rivers
- by fish such as Salmo salmon: - ANSWER ✓ probably derives from a trophic
adaptation in freshwater fishes
Insulin release results in all of the following physiological effects EXCEPT: -
ANSWER ✓ decreased glycogen stores in liver cells
The endosperm of a plant with "monosporic" development has 72 chromosomes.
How many chromosomes does the egg cell have? - ANSWER ✓ 24
An allergic reaction is caused by an antigen with this class of immunoglubin: -
ANSWER ✓ IgE
What effect do sexual processes (meiosis and fertilization) have on allele
frequencies in a population? - ANSWER ✓ They have no direct effect on allele
frequencies.
A mutation in the gene encoding cyclin D: - ANSWER ✓ A,B, or C
The velocity of carrier-mediated diffusion across cellular membranes: - ANSWER
✓ can increase up to a maximum value
Insulin injected by diabetics to control blood sugar levels is derived from bacteria
whose DNA has been modified by the addition of the human gene for insulin,
which is then produced by the prokaryotes. This is an example of: - ANSWER ✓
genetic engineering
WITH CORRECT SOLUTIONS||100%
GUARANTEED PASS|| A+
GRADED||UPDATED 2025/2026
SYLLABUS||<<NEWEST VERSION>>
A red pigment is extracted from a marine alga. Which best supports the hypothesis
that the pigment is involved in photosynthesis? The red pigment: - ANSWER ✓
has an absorption spectrum similar to the photosynthetic action spectrum for that
same marine alga
Given the following pedigree: What is (are) the possible mode(s) of inheritance? I.
Autosomal dominant II. Autosomal recessive III. X-linked dominant IV. X-linked
recessive (question 25 of 2005 exam) - ANSWER ✓ II or IV only
Color-blindness is a recessive, X-linked trait. A couple, who are both blood type A
and who both have normal vision, have a son who is blood type O and colorblind.
What is the probability that their next child will be a daughter who is blood type O
and has normal vision? - ANSWER ✓ 1/8
A strain of bacteria living in a hospital is found to have a plasmid containing two
genes: one for sex pilus construction, and one for tetracycline resistance. If these
bacteria were to undergo conjugation with bacteria lacking this plasmid, and thus
transferred the plasmid to the other bacteria, the most likely result would be: -
ANSWER ✓ rapid spread of tetracycline resistance to other bacteria in the hospital
How do Aspirin and Ibuprofen produce anti-inflammatory effects? - ANSWER ✓
by inhibiting prostaglandin synthesis
Group hunting can favorably influence the ability to obtain different food
resources and the efficiency of a capture as a result of: - ANSWER ✓ increased
chance of capturing larger prey
, A fruit with an endocarp composed of sclerenchyma cells, but fleshy mesocarp
and exocarp, is called a: - ANSWER ✓ drupe
Most of today's biological diversity has arisen via: - ANSWER ✓ cladogenesis
Which of the following would act as an "uncoupler" of electron transport and ATP
synthesis in the mitochondrion? - ANSWER ✓ A and C only (dinitrophenol and
the F0 base piece of the ATP synthase (without the F1 subunit))
Concentration of urine is essential to the survival of many vertebrates. Which
class of vertebrates would you expect does not use this mechanism for
homeostasis? - ANSWER ✓ Osteichthyes
A comparison of the energy expenditures (kcal/kg/day) for a penguin and for a
python (assuming they are of equal size) would show that: - ANSWER ✓ the
energy expenditure of the penguin is greater than that for the python
Which of the following is the least dependable method for determining the adaxial
surface of a leaf? - ANSWER ✓ the distribution of stomata
What is the probability of obtaining the given genotype in the offspring,
AAbbCCdd, from the parents AaBbCcDd x AABbCcDd (assume independent
assortment of all gene pairs)? - ANSWER ✓ 1/128
Which of the following statements is NOT characteristic of polygyny? -
ANSWER ✓ Females compete for 'status' in communal displays (leks) and males
choose among females
The inner surface of the urethra, the tube through which urine exits the body, is
lined with which type of epithelial cells? - ANSWER ✓ stratified columnar
epithelia
Which of the following are characteristics of both bacteria and fungi? - ANSWER
✓ cell wall, DNA, and plasma membrane
Net primary productivity, in most ecosystems, is important because it represents
the: - ANSWER ✓ storage of chemical energy that would be available to
heterotrophs
, In general, where are the vessels found in "ring porous wood?" - ANSWER ✓ in
the spring wood
Terminally differentiated cells are most often found in which phase of the cell
cycle? - ANSWER ✓ G0
During the first 6 to 8 weeks of gestation, the principal source of estrogen and
progesterone is: - ANSWER ✓ corpus luteum
There is evidence that anadromous migration - from ocean to headwaters of rivers
- by fish such as Salmo salmon: - ANSWER ✓ probably derives from a trophic
adaptation in freshwater fishes
Insulin release results in all of the following physiological effects EXCEPT: -
ANSWER ✓ decreased glycogen stores in liver cells
The endosperm of a plant with "monosporic" development has 72 chromosomes.
How many chromosomes does the egg cell have? - ANSWER ✓ 24
An allergic reaction is caused by an antigen with this class of immunoglubin: -
ANSWER ✓ IgE
What effect do sexual processes (meiosis and fertilization) have on allele
frequencies in a population? - ANSWER ✓ They have no direct effect on allele
frequencies.
A mutation in the gene encoding cyclin D: - ANSWER ✓ A,B, or C
The velocity of carrier-mediated diffusion across cellular membranes: - ANSWER
✓ can increase up to a maximum value
Insulin injected by diabetics to control blood sugar levels is derived from bacteria
whose DNA has been modified by the addition of the human gene for insulin,
which is then produced by the prokaryotes. This is an example of: - ANSWER ✓
genetic engineering
