USABO Open Exam (ACTUAL2
P P P P
025-
2026) | 100% Correct Answers |
P P P P P P
Verified | P
,Which of the following ions have higher extracellularc
P P P P P P P P
oncentrations than intracellular concentrations? P P P
I. Potassium
II. Sodium
III. Calcium
A. I only
P
B. II only P
C. I and II
P P
D. I, II, and III
P P P
E. II and III - <<<Answers>>>E. II and III
P P P P P P P
Select the statement that best describes movement of O2 ,N
P P P P P P P P P P
a+ , and glucose into and out of the capillaries.
P P P P P P P P P
A. O2 and glucose diffuse across endothelial cell membranes;N
P P P P P P P P
a+ diffuses through pores between cells.
P P P P P
B. O2 and Na+ diffuse across endothelial cell membranes;g
P P P P P P P P
lucose diffuses through pores between cells.
P P P P P
C. O2 diffuses across endothelial cell membranes; Na+ andg
P P P P P P P P
lucose diffuse through pores between cells.
P P P P P
D. O2 , Na+, and glucose all diffuse across endothelial cellm
P P P P P P P P P P
embranes.
E. O2 , Na+ , and glucose all diffuse through pores betweenen
P P P P P P P P P P P
dothelial cells. - <<<Answers>>>C. O2 diffuses across
P P P P P P
, endothelial cell membranes; Na+ and glucose diffuse throughp
P P P P P P P P
ores between cells.
P P
A new chemical is found that inhibits muscle function and in hig
P P P P P P P P P P P
h enough doses causes paralysis. Which of the following isNOT
P P P P P P P P P P
a plausible mechanism by which this chemical could function?
P P P P P P P P P
A. Inhibition of acetylcholinesterase in the synaptic cleft ofp
P P P P P P P P
eripheral motor neurons. P P
B. Inhibition of acetylcholine release in peripheral motorn
P P P P P P P
eurons.
C. Inhibition of calcium release in peripheral motor neurons.
P P P P P P P
D. Inhibition of the binding of myosin heads to actin filamentsin
P P P P P P P P P P
muscle cells.
P P
E. Inhibition of calcium- P P
release channels in the sarcoplasmicreticulum of muscle cells.
P P P P P P P P P
-
<<<Answers>>>C. Inhibition ofcalcium release in peripheral
P P P P P P P
motor neurons.
P P
A dog breeder wants to breed dogs with thick, shaggy coats.As
P P P P P P P P P P P
sume that the thick-
P P P
coat trait is recessive. Two dogs, bothwith thick coats and of th
P P P P P P P P P P P P
e same breed, are mated, but all thepuppies are short-
P P P P P P P P P P
haired. From this you can conclude that...
P P P P P P
A. Having two copies of the thick coat allele is lethal.
P P P P P P P P P
P P P P
025-
2026) | 100% Correct Answers |
P P P P P P
Verified | P
,Which of the following ions have higher extracellularc
P P P P P P P P
oncentrations than intracellular concentrations? P P P
I. Potassium
II. Sodium
III. Calcium
A. I only
P
B. II only P
C. I and II
P P
D. I, II, and III
P P P
E. II and III - <<<Answers>>>E. II and III
P P P P P P P
Select the statement that best describes movement of O2 ,N
P P P P P P P P P P
a+ , and glucose into and out of the capillaries.
P P P P P P P P P
A. O2 and glucose diffuse across endothelial cell membranes;N
P P P P P P P P
a+ diffuses through pores between cells.
P P P P P
B. O2 and Na+ diffuse across endothelial cell membranes;g
P P P P P P P P
lucose diffuses through pores between cells.
P P P P P
C. O2 diffuses across endothelial cell membranes; Na+ andg
P P P P P P P P
lucose diffuse through pores between cells.
P P P P P
D. O2 , Na+, and glucose all diffuse across endothelial cellm
P P P P P P P P P P
embranes.
E. O2 , Na+ , and glucose all diffuse through pores betweenen
P P P P P P P P P P P
dothelial cells. - <<<Answers>>>C. O2 diffuses across
P P P P P P
, endothelial cell membranes; Na+ and glucose diffuse throughp
P P P P P P P P
ores between cells.
P P
A new chemical is found that inhibits muscle function and in hig
P P P P P P P P P P P
h enough doses causes paralysis. Which of the following isNOT
P P P P P P P P P P
a plausible mechanism by which this chemical could function?
P P P P P P P P P
A. Inhibition of acetylcholinesterase in the synaptic cleft ofp
P P P P P P P P
eripheral motor neurons. P P
B. Inhibition of acetylcholine release in peripheral motorn
P P P P P P P
eurons.
C. Inhibition of calcium release in peripheral motor neurons.
P P P P P P P
D. Inhibition of the binding of myosin heads to actin filamentsin
P P P P P P P P P P
muscle cells.
P P
E. Inhibition of calcium- P P
release channels in the sarcoplasmicreticulum of muscle cells.
P P P P P P P P P
-
<<<Answers>>>C. Inhibition ofcalcium release in peripheral
P P P P P P P
motor neurons.
P P
A dog breeder wants to breed dogs with thick, shaggy coats.As
P P P P P P P P P P P
sume that the thick-
P P P
coat trait is recessive. Two dogs, bothwith thick coats and of th
P P P P P P P P P P P P
e same breed, are mated, but all thepuppies are short-
P P P P P P P P P P
haired. From this you can conclude that...
P P P P P P
A. Having two copies of the thick coat allele is lethal.
P P P P P P P P P
