USMLE STEP 1FULL SOLUTION PACK(6
Versions)Bundled exams with complete solution
USMLE Step 1
A 65-year-old man is admitted to the hospital because of a 12-hour history of chest
pain. Physical examination shows no abnormalities. Serum studies show an increased
troponin I concentration. The diagnosis of myocardial infarction is made. It is suspected
that this patient's condition deteriorated as a result of ischemia-reperfusion injury. The
increased serum troponin I concentration in this patient most likely occurred as a result
of which of the following processes? - ANSWERS-Lysis of the plasma membrane
A randomized clinical trial is conducted to compare wound healing and cosmetic
differences between two surgical procedures for closing skin wounds following cesarean
delivery. A total of 1000 women undergoing cesarean delivery during a 6-month period
are enrolled in the study, which was 85% of the total number of patients undergoing the
procedure. The results show a wound infection rate of 12 cases per 1000 women for
Procedure A and 18 cases per 1000 women for Procedure B. Which of the following is
the best estimate of the absolute risk reduction for wound infection following Procedure
A compared with Procedure B? - ANSWERS-(18/1000) - (12/1000)
A 22-year-old man is brought to the emergency department 15 minutes after diving off a
pier into shallow water, striking his forehead on the bottom of the pond. He says that he
felt immediate pain in his neck and then lost all ability to move or feel his legs. Physical
examination shows that all muscle function above the level of the injury is preserved. A
lateral x-ray of the cervical spine is shown. Which of the following functions is most
likely spared in this patient? - ANSWERS-Elbow flexion
Serum LDL-cholesterol concentrations are measured in blood samples collected from
25 healthy volunteers. The data follow a normal distribution. The mean and standard
deviation for this group are 130 mg/dL and 25 mg/dL, respectively. The standard error
of the mean is 5.0. With a 95% confidence level, the true mean for the population from
which this sample was drawn falls within which of the following ranges (in mg/dL)? -
ANSWERS-120-140
A 48-year-old man dies suddenly of a cardiac arrhythmia. Six weeks ago, he was
resuscitated from a cardiac arrest caused by coronary artery disease and developed
oliguric renal failure. Five weeks ago (1 week after being resuscitated), his serum urea
,nitrogen (BUN) concentration was 40 mg/dL, his serum creatinine concentration was 3.5
mg/dL, and his urine contained granular casts. Four weeks ago, his oliguria resolved,
and his BUN and serum creatinine concentrations returned to normal. Examination of
his kidneys at autopsy is most likely to show which of the following? - ANSWERS-
Normal Kidney
In a sample of 100 individuals, the mean leukocyte count is 7500/mm3 , with a standard
deviation of 1000/mm3 . If the leukocyte counts in this population follow a normal
(gaussian) distribution, approximately 50% of individuals will have which of the following
total leukocyte counts? - ANSWERS-<7500/mm^3
A 55-year-old woman comes to the clinic because of a 2-month history of increasingly
severe vaginal pain and itching during sexual intercourse. She avoids intercourse with
her husband because of the symptoms. She has been in a monogamous relationship
with her husband for the past 25 years. She has type 2 diabetes mellitus. Her vital signs
are within normal limits. Pelvic examination shows edematous and erythematous
vaginal mucosa with white discharge. A photomicrograph of a vaginal smear is shown.
Which of the following is the most likely causal infectious agent? - ANSWERS-Candida
albicans
A 39-year-old man comes to the physician because of a 6-month history of progressive
shortness of breath. He has had a cough productive of white sputum for 2 years. He
smoked 1 pack of cigarettes daily for 16 years but quit 10 years ago. He is in mild
respiratory distress with pursed lips and a barrel chest; he is using the accessory
muscles of respiration. Breath sounds are distant and crackles are present in the lower
lung fields bilaterally. Pulmonary function tests show a decreased FEV1:FVC ratio,
increased residual volume, and decreased diffusion capacity. An x-ray of the chest
shows hyperinflation and hypertranslucency of the lower lobes of both lungs. Which of
the following is the most likely diagnosis? - ANSWERS-Emphysema
A previously healthy 33-year-old woman is brought to the emergency department by the
Secret Service for stalking the president of the USA for 2 months. She claims to be
married to the president's twin brother and states that the president just had his twin
kidnapped to avoid competition. She speaks rapidly and is difficult to interrupt. Her
associations are often loose. She says, "I haven't slept for days, but I won't even try to
sleep until my husband is rescued. God has been instructing me to take over th e White
House. I can't wait to be reunited with my husband. I hear his voice telling me what to
do." When asked about drug use, she says she uses only natural substances. She
refuses to permit blood or urine tests, saying, "I don't have time to wait for th e results."
Which of the following is the most likely diagnosis? - ANSWERS-Bipolar disorder,
manic, with psychotic features
During an experiment, a mouse is vaccinated with live attenuated bacteria at two
different times. The results following immunization are shown in the graph. The subject's
serum total antibody concentration (Y-axis) was measured at various time points (X-
axis). The response to the first immunization is indicated by Peak A, while that of the
,second immunization with the same bacterial antigen is indicated by Peak B. The phase
of the immune response represented by the asterisk is most likely the direct result of
which of the following? - ANSWERS-Apoptosis of activated lymphocytes
A 53-year-old man comes to the physician because of a dry scaly rash on his body for
the past year. He has had a 15- kg (33-lb) weight loss during the past year. He is 178
cm (5 ft 10 in) tall and now weighs 54 kg (120 lb); BMI is 17 kg/m2 . His stools have a
large volume and float. Which of the following nutrient deficiencies is most likely? -
ANSWERS-Vitamin A
In screening for prostate cancer, the current serum prostate-specific antigen
concentration at which biopsy is recommended is 4.1 ng/mL. If the threshold for
recommending a biopsy procedure were lowered to 2.0 ng/mL, which of the following
changes would occur to the positive and negative predictive values of the test? -
ANSWERS-G
In informing a couple that their newborn has Down syndrome, there is a specific,
relatively limited amount of information that the consulting physician should give
immediately. The rest can be discussed at a later time. Which of the following best
explains the purpose of using this approach to disclosure? - ANSWERS-Disclosing the
most important information so that it can be understood as fully as possible
A 25-year-old man volunteers to participate in a study of exercise. The solid curves in
the graph show the relationship between right atrial pressure and cardiac output
(cardiac function curves). The dashed lines show the relationship between cardiac
output and right atrial pressure (vascular function curves). Point X is the pre-exercise
equilibrium point. Which of the following labeled areas is the most likely new cardiac
and vascular equilibrium point during exercise in this subject? - ANSWERS-H
A 62-year-old man comes to the physician because of a 6-month history of urinary
hesitancy and dribbling after urination. He has to urinate two to three times nightly.
Physical examination shows a diffusely enlarged, firm, and nontender prostate. Which
of the following is most likely to have contributed to the development of this patient's
condition? - ANSWERS-Conversion of testosterone to dihydrotestosterone
An 18-year-old woman with sickle cell disease is brought to the emergency department
by her parents because of a 2- hour history of severe abdominal pain and nausea. Her
parents say that she had a cheeseburger, milk shake, and chocolate bar for lunch. Her
temperature is 37°C (98.6°F). Physical examination shows tenderness over the right
upper quadrant of the abdomen, radiating to the right shoulder. Ultrasonography of the
right upper quadrant of the abdomen shows gallstones. Which of the following is the
most likely underlying cause of this patient's current condition? - ANSWERS-Overload
of unconjugated bilirubin
A 45-year-old man is brought to the emergency department 30 minutes after the sudden
onset of crushing chest pain. His father, maternal aunt, and paternal uncle all died of
, myocardial infarctions under the age of 50 years. Physical examination shows
tendinous xanthomas on the hands and thickened Achilles tendons. Serum lipid studies
show a total cholesterol concentration of 410 mg/dL, HDL-cholesterol concentration of
30 mg/dL, and triglyceride concentration of 140 mg/dL. The diagnosis of myocardial
infarction is made. This patient most likely has a deficiency of which of the following? -
ANSWERS-LDL receptor
An experimental animal is created in which the germinal centers of the reactive lymph
nodes show shrinkage of cells, cytoplasmic budding, no adjacent inflammation, and
intact plasma membranes. These cellular findings are most likely caused by which of
the following mechanisms? - ANSWERS-Caspase activation
Investigators conduct a study that evaluates the effect of finasteride on the incidence of
prostate cancer in 500 patients. The investigators recruit an additional 1000 patients for
the study. Which of the following effects will this have on the research study? -
ANSWERS-Less chance of a Type II error
A 76-year-old man dies of a massive cerebral infarction shortly after admission to the
hospital. During the past 10 years, he has had several smaller cerebral infarctions and
two transient ischemic attacks. Examination of a cerebral cortex specimen obtained at
autopsy shows extensive gliosis. This finding is most likely caused by the growth and
proliferation of which of the following? - ANSWERS-Astrocytes
A 65-year-old woman is brought to the emergency department because of a 10-minute
history of chest tightness and severe pain of her left arm. Physical examination shows
jugular venous distention. Crackles are heard over the lung fields. An ECG shows ST-
segment elevation greater than 1 mm in leads V4 through V6 and new Q waves. Serum
studies show an increased troponin I concentration. Which of the following labeled
points in the graph best represents the changes in cardiac function that occurred during
the first 10 seconds after the onset of pain in this patient? - ANSWERS-W → Z
A previously healthy 52-year-old woman comes to the physician because of a 2-month
history of fatigue, constipation, and frequent urination. Her temperature is 37.1°C
(98.8°F), pulse is 80/min, respirations are 14/min, and blood pressure is 140/90 mm Hg.
Diffuse crackles are heard bilaterally. Her serum calcium concentration is 11.1 mg/dL,
and serum parathyroid hormone concentration is decreased. A chest x-ray shows
bilateral hilar lymphadenopathy and interstitial infiltrates. Which of the following is the
most likely cause of this patient's hypercalcemia? - ANSWERS-Calcitriol production by
activated macrophages
A 66-year-old man who was recently diagnosed with Parkinson disease comes to the
physician for a follow-up examination. Carbidopa-levodopa therapy was initiated at the
time of diagnosis. The patient tells the physician that he still has episodes during whi ch
he "freezes." He has a clumsy gait, and there is rigidity of his upper extremities and
hands. An adjunct therapy designed to inhibit which of the following enzymes is most
likely indicated in this patient? - ANSWERS-Monoamine oxidase B
Versions)Bundled exams with complete solution
USMLE Step 1
A 65-year-old man is admitted to the hospital because of a 12-hour history of chest
pain. Physical examination shows no abnormalities. Serum studies show an increased
troponin I concentration. The diagnosis of myocardial infarction is made. It is suspected
that this patient's condition deteriorated as a result of ischemia-reperfusion injury. The
increased serum troponin I concentration in this patient most likely occurred as a result
of which of the following processes? - ANSWERS-Lysis of the plasma membrane
A randomized clinical trial is conducted to compare wound healing and cosmetic
differences between two surgical procedures for closing skin wounds following cesarean
delivery. A total of 1000 women undergoing cesarean delivery during a 6-month period
are enrolled in the study, which was 85% of the total number of patients undergoing the
procedure. The results show a wound infection rate of 12 cases per 1000 women for
Procedure A and 18 cases per 1000 women for Procedure B. Which of the following is
the best estimate of the absolute risk reduction for wound infection following Procedure
A compared with Procedure B? - ANSWERS-(18/1000) - (12/1000)
A 22-year-old man is brought to the emergency department 15 minutes after diving off a
pier into shallow water, striking his forehead on the bottom of the pond. He says that he
felt immediate pain in his neck and then lost all ability to move or feel his legs. Physical
examination shows that all muscle function above the level of the injury is preserved. A
lateral x-ray of the cervical spine is shown. Which of the following functions is most
likely spared in this patient? - ANSWERS-Elbow flexion
Serum LDL-cholesterol concentrations are measured in blood samples collected from
25 healthy volunteers. The data follow a normal distribution. The mean and standard
deviation for this group are 130 mg/dL and 25 mg/dL, respectively. The standard error
of the mean is 5.0. With a 95% confidence level, the true mean for the population from
which this sample was drawn falls within which of the following ranges (in mg/dL)? -
ANSWERS-120-140
A 48-year-old man dies suddenly of a cardiac arrhythmia. Six weeks ago, he was
resuscitated from a cardiac arrest caused by coronary artery disease and developed
oliguric renal failure. Five weeks ago (1 week after being resuscitated), his serum urea
,nitrogen (BUN) concentration was 40 mg/dL, his serum creatinine concentration was 3.5
mg/dL, and his urine contained granular casts. Four weeks ago, his oliguria resolved,
and his BUN and serum creatinine concentrations returned to normal. Examination of
his kidneys at autopsy is most likely to show which of the following? - ANSWERS-
Normal Kidney
In a sample of 100 individuals, the mean leukocyte count is 7500/mm3 , with a standard
deviation of 1000/mm3 . If the leukocyte counts in this population follow a normal
(gaussian) distribution, approximately 50% of individuals will have which of the following
total leukocyte counts? - ANSWERS-<7500/mm^3
A 55-year-old woman comes to the clinic because of a 2-month history of increasingly
severe vaginal pain and itching during sexual intercourse. She avoids intercourse with
her husband because of the symptoms. She has been in a monogamous relationship
with her husband for the past 25 years. She has type 2 diabetes mellitus. Her vital signs
are within normal limits. Pelvic examination shows edematous and erythematous
vaginal mucosa with white discharge. A photomicrograph of a vaginal smear is shown.
Which of the following is the most likely causal infectious agent? - ANSWERS-Candida
albicans
A 39-year-old man comes to the physician because of a 6-month history of progressive
shortness of breath. He has had a cough productive of white sputum for 2 years. He
smoked 1 pack of cigarettes daily for 16 years but quit 10 years ago. He is in mild
respiratory distress with pursed lips and a barrel chest; he is using the accessory
muscles of respiration. Breath sounds are distant and crackles are present in the lower
lung fields bilaterally. Pulmonary function tests show a decreased FEV1:FVC ratio,
increased residual volume, and decreased diffusion capacity. An x-ray of the chest
shows hyperinflation and hypertranslucency of the lower lobes of both lungs. Which of
the following is the most likely diagnosis? - ANSWERS-Emphysema
A previously healthy 33-year-old woman is brought to the emergency department by the
Secret Service for stalking the president of the USA for 2 months. She claims to be
married to the president's twin brother and states that the president just had his twin
kidnapped to avoid competition. She speaks rapidly and is difficult to interrupt. Her
associations are often loose. She says, "I haven't slept for days, but I won't even try to
sleep until my husband is rescued. God has been instructing me to take over th e White
House. I can't wait to be reunited with my husband. I hear his voice telling me what to
do." When asked about drug use, she says she uses only natural substances. She
refuses to permit blood or urine tests, saying, "I don't have time to wait for th e results."
Which of the following is the most likely diagnosis? - ANSWERS-Bipolar disorder,
manic, with psychotic features
During an experiment, a mouse is vaccinated with live attenuated bacteria at two
different times. The results following immunization are shown in the graph. The subject's
serum total antibody concentration (Y-axis) was measured at various time points (X-
axis). The response to the first immunization is indicated by Peak A, while that of the
,second immunization with the same bacterial antigen is indicated by Peak B. The phase
of the immune response represented by the asterisk is most likely the direct result of
which of the following? - ANSWERS-Apoptosis of activated lymphocytes
A 53-year-old man comes to the physician because of a dry scaly rash on his body for
the past year. He has had a 15- kg (33-lb) weight loss during the past year. He is 178
cm (5 ft 10 in) tall and now weighs 54 kg (120 lb); BMI is 17 kg/m2 . His stools have a
large volume and float. Which of the following nutrient deficiencies is most likely? -
ANSWERS-Vitamin A
In screening for prostate cancer, the current serum prostate-specific antigen
concentration at which biopsy is recommended is 4.1 ng/mL. If the threshold for
recommending a biopsy procedure were lowered to 2.0 ng/mL, which of the following
changes would occur to the positive and negative predictive values of the test? -
ANSWERS-G
In informing a couple that their newborn has Down syndrome, there is a specific,
relatively limited amount of information that the consulting physician should give
immediately. The rest can be discussed at a later time. Which of the following best
explains the purpose of using this approach to disclosure? - ANSWERS-Disclosing the
most important information so that it can be understood as fully as possible
A 25-year-old man volunteers to participate in a study of exercise. The solid curves in
the graph show the relationship between right atrial pressure and cardiac output
(cardiac function curves). The dashed lines show the relationship between cardiac
output and right atrial pressure (vascular function curves). Point X is the pre-exercise
equilibrium point. Which of the following labeled areas is the most likely new cardiac
and vascular equilibrium point during exercise in this subject? - ANSWERS-H
A 62-year-old man comes to the physician because of a 6-month history of urinary
hesitancy and dribbling after urination. He has to urinate two to three times nightly.
Physical examination shows a diffusely enlarged, firm, and nontender prostate. Which
of the following is most likely to have contributed to the development of this patient's
condition? - ANSWERS-Conversion of testosterone to dihydrotestosterone
An 18-year-old woman with sickle cell disease is brought to the emergency department
by her parents because of a 2- hour history of severe abdominal pain and nausea. Her
parents say that she had a cheeseburger, milk shake, and chocolate bar for lunch. Her
temperature is 37°C (98.6°F). Physical examination shows tenderness over the right
upper quadrant of the abdomen, radiating to the right shoulder. Ultrasonography of the
right upper quadrant of the abdomen shows gallstones. Which of the following is the
most likely underlying cause of this patient's current condition? - ANSWERS-Overload
of unconjugated bilirubin
A 45-year-old man is brought to the emergency department 30 minutes after the sudden
onset of crushing chest pain. His father, maternal aunt, and paternal uncle all died of
, myocardial infarctions under the age of 50 years. Physical examination shows
tendinous xanthomas on the hands and thickened Achilles tendons. Serum lipid studies
show a total cholesterol concentration of 410 mg/dL, HDL-cholesterol concentration of
30 mg/dL, and triglyceride concentration of 140 mg/dL. The diagnosis of myocardial
infarction is made. This patient most likely has a deficiency of which of the following? -
ANSWERS-LDL receptor
An experimental animal is created in which the germinal centers of the reactive lymph
nodes show shrinkage of cells, cytoplasmic budding, no adjacent inflammation, and
intact plasma membranes. These cellular findings are most likely caused by which of
the following mechanisms? - ANSWERS-Caspase activation
Investigators conduct a study that evaluates the effect of finasteride on the incidence of
prostate cancer in 500 patients. The investigators recruit an additional 1000 patients for
the study. Which of the following effects will this have on the research study? -
ANSWERS-Less chance of a Type II error
A 76-year-old man dies of a massive cerebral infarction shortly after admission to the
hospital. During the past 10 years, he has had several smaller cerebral infarctions and
two transient ischemic attacks. Examination of a cerebral cortex specimen obtained at
autopsy shows extensive gliosis. This finding is most likely caused by the growth and
proliferation of which of the following? - ANSWERS-Astrocytes
A 65-year-old woman is brought to the emergency department because of a 10-minute
history of chest tightness and severe pain of her left arm. Physical examination shows
jugular venous distention. Crackles are heard over the lung fields. An ECG shows ST-
segment elevation greater than 1 mm in leads V4 through V6 and new Q waves. Serum
studies show an increased troponin I concentration. Which of the following labeled
points in the graph best represents the changes in cardiac function that occurred during
the first 10 seconds after the onset of pain in this patient? - ANSWERS-W → Z
A previously healthy 52-year-old woman comes to the physician because of a 2-month
history of fatigue, constipation, and frequent urination. Her temperature is 37.1°C
(98.8°F), pulse is 80/min, respirations are 14/min, and blood pressure is 140/90 mm Hg.
Diffuse crackles are heard bilaterally. Her serum calcium concentration is 11.1 mg/dL,
and serum parathyroid hormone concentration is decreased. A chest x-ray shows
bilateral hilar lymphadenopathy and interstitial infiltrates. Which of the following is the
most likely cause of this patient's hypercalcemia? - ANSWERS-Calcitriol production by
activated macrophages
A 66-year-old man who was recently diagnosed with Parkinson disease comes to the
physician for a follow-up examination. Carbidopa-levodopa therapy was initiated at the
time of diagnosis. The patient tells the physician that he still has episodes during whi ch
he "freezes." He has a clumsy gait, and there is rigidity of his upper extremities and
hands. An adjunct therapy designed to inhibit which of the following enzymes is most
likely indicated in this patient? - ANSWERS-Monoamine oxidase B
