NBME CBSE ACTUAL TEST QUESTIONS AND ANSWERS
2024/2025(Quiz bank with all the correct answers)(usmle step
1)Medical examination
1 Exam Section 1: Item 1 of 50
v v v v v v
National Board of Medical Examiners®
v v v v
Comprehensive Basic Science Self-Assessment v v v
1. Shortly after delivery, a full-term male newborn is found to have black hair with a white forelock. His
v v v v v v v v v v v v v v v v v v
mother, a brunette, also has a white forelock and wears hearing aids. Physical examination shows
v v v v v v v v v v v v v v v
heterochromia of irides. Otoacoustic emissions testing and
v v v v v v v
brain stem auditory evoked responses show bilateral sensorineural hearing loss. Which of the following
v v v v v v v v v v v v v
is the most likely cause of the findings in this patient?
v v v v v v v v v v v
A) Abnormal neural crest development
v v v v
B) Abnormality of connexins
v v v
C) Deficiency of homogentisic acid oxidase activity
v v v v v v
D) Deficiency of tyrosinase activity
v v v v
E) Failure of internalization of melanin granules by keratinocytes
v v v v v v v v
F) Failure of melanosome transportation along dendrites - ANSW -A.
v v v v v v v v v
Abnormal neural crest development leads to Waardenburg syndrome. Waardenburg syndrome is a
v v v v v v v v v v v
syndrome of patchy depigmentation of the skin, hair, irises, and cochlear dysfunction that primarily
v v v v v v v v v v v v v v
illustrates an autosomal dominant inheritance pattern. Because of
v v v v v v v v
genetic mutations of genes encoding transcription factors, neural crest cells do not properly
v v v v v v v v v v v v
differentiate into melanoblasts (melanocyte precursors), or melanoblasts do not migrate to their
v v v v v v v v v v v v
appropriate location. Patients typically have a white forelock and eyelashes,
v v v v v v v v v v
depigmented skin patches, iridic heterochromia, and sensorineural deafness. The eyes may also be
v v v v v v v v v v v v
laterally displaced. The clinical diagnosis may be confirmed with genetic testing. Treatment includes
v v v v v v v v v v v v v
audiologic evaluation and genetic consultation.
v v v v v
Incorrect Answers: B, C, D, E, and F.
v v v v v v v
An abnormality of connexins (Choice B) would lead to abnormal formation of the plasma membrane
v v v v v v v v v v v v v v
channels of diverse cell types. Different combinations of sensorineural hearing loss, ichthyosis,
v v v v v v v v v v v v
alopecia, and peripheral neuropathy may occur. Depigmentation
v v v v v v v
would be atypical. v v
,Deficiency of homogentisic acid oxidase activity (Choice C) would lead to decreased metabolism of the
v v v v v v v v v v v v v v
amino acids phenylalanine and tyrosine, which instead degrade into homogentisic acid. Homogentisic
v v v v v v v v v v v v
acid accumulates in the skin and joints, causing increased
v v v v v v v v v
pigmentation and arthritis, respectively. Depigmentation would be atypical. v v v v v v v
Deficiency of tyrosinase activity (Choice D) occurs in oculocutaneous albinism, which presents with
v v v v v v v v v v v v
uniformly hypopigmented hair and skin (versus the patchy depigmentation of Waardenburg syndrome)
v v v v v v v v v v v v
and eye abnormalities (eg, iris hypopigmentation, refractive
v v v v v v v
errors, nystagmus). In tyrosinase deficiency, melanocytes are unable to synthesize melanin from the
v v v v v v v v v v v v
amino acid tyrosine. Iridic heterochromia and sensorineural deafnes
v v v v v v v v
10
Exam Section 1: Item 10 of 50
v v v v v v
National Board of Medical Examiners® v v v v
Comprehensive Basic Science Self-Assessment v v v
10. A 12-year-old boy is brought to the physician by his parents because of bed-wetting. He urinates 10
v v v v v v v v v v v v v v v v v
to 15 times each day. He says that he is constantly thirsty and drinks large quantities of liquid
v v v v v v v v v v v v v v v v v v
throughout the day. Urinalysis shows a specific gravity of
v v v v v v v v v
1.003. A 24-hour urine collection shows a creatinine clearance of 140 mL/min, with a total urine volume
v v v v v v v v v v v v v v v v
of 7600 mL and urine osmolality of 230 mOsmol/kg H,O. A tumor affecting which of the following
v v v v v v v v v v v v v v v v v
hypothalamic nuclei is most likely involved in producing
v v v v v v v v
this patient's symptoms?
v v
A) Anterior
v
B) Arcuate
v
C) Dorsomedial
v
D) Lateral
v
E) Posterior
v
F) Supraoptic
v
G) Ventromedial - ANSW -F.
v v v v
Central diabetes insipidus may result from a tumor involving the hypothalamic paraventricular and
v v v v v v v v v v v v
supraoptic nuclei and is characterized by the inadequate secretion of antidiuretic hormone (ADH, also
v v v v v v v v v v v v v v
known as vasopressin) from the posterior pituitary. Normally,
v v v v v v v v
increased plasma osmolality will be sensed by osmoreceptors and result in the increased production of
v v v v v v v v v v v v v v
vvasopressin in the hypothalamic paraventricular and supraoptic nuclei. Vasopressin is subsequently
v v v v v v v v v v
vreleased by the posterior pituitary gland. ADH binds V2
v v v v v v v v
,receptors of the late distal convoluted tubule and the collecting duct principal cells, which results in the
v v v v v v v v v v v v v v v v
insertion of aquaporin channels in the luminal surface and increases free water absorption. This
v v v v v v v v v v v v v v
process is typically utilized to maintain tight regulation of the
v v v v v v v v v v
serum osmolality. Inadequate production of ADH by the hypothalamus and release by the posterior
v v v v v v v v v v v v v
pituitary gland may occur in the setting of various pathologies, such as pituitary tumors, trauma,
v v v v v v v v v v v v v v v
tuberculosis, or intracranial surgery. This results in a decreased
v v v v v v v v v
ability to absorb adequate amounts of free water within the collecting duct, which results in dilute
v v v v v v v v v v v v v v v
urine and increased serum osmolality. Patients typically present with extreme thirst, production of
v v v v v v v v v v v v v
large volumes of dilute urine, and altered mental status. Treatment
v v v v v v v v v v
requires the administration of desmopressin, an analog of vasopressin (ADH), which results in the
v v v v v v v v v v v v v
reabsorption of free water via aquaporin insertion in the collecting duct.
v v v v v v v v v v v
Incorrect Answers: A, B, C, D, E, and G.v v v v v v v v
The anterior hypothalamic nucleus (Choice A) is involved in thermoregulation, specifically in cooling.
v v v v v v v v v v v v
The arcuate hypothalamic nucleus (Choice B) contains complex regulatory functions that are involved in
v v v v v v v v v v v v v
appetite stimulation.
v v
The dorsomedial hypothalamic nucleus (Choice C) is involved in the regulation of fe
v v v v v v v v v v v v
100
Exam Section 2: Item 50 of 50
v v v v v v
National Board of Medical Examiners®v v v v
Comprehensive Basic Science Self-Assessment v v v
50. A 16-month-old girl is brought to the physician because she has refused to move her right arm since
v v v v v v v v v v v v v v v v v v
her older brother grabbed her right hand 1 hour ago to stop her from running into the street. On
v v v v v v v v v v v v v v v v v v v
examination, she is holding the right arm in pronation. Any
v v v v v v v v v v
motion of the right elbow produces pain. There is no visible edema. Which of the following is the most
v v v v v v v v v v v v v v v v v v
likely explanation for these findings?
v v v v v
A) Dislocation of the shoulder
v v v v
B) Fracture of the distal radius and ulna
v v v v v v v
C) Salter-Harris type I fracture of the humerus
v v v v v v v
D) Septic arthritis
v v
E) Subluxation of the radial head - ANSW -E.
v v v v v v v v
Dislocation or subluxation of the radial head is a common pediatric injury, known as a nursemaid
v v v v v v v v v v v v v v v
elbow. It results from traction on the radial head, which displaces it from within its ligamentous
v v v v v v v v v v v v v v v v
annulus. This most often occurs in children of age 12-36 months, and
v v v v v v v v v v v v
, often arises from defensive maneuvers by parents or caretakers when grabbing the child's arm to
v v v v v v v v v v v v v v
prevent running into traffic or similarly endangering oneself. It can also arise from routine play if a
v v v v v v v v v v v v v v v v v
parent, older sibling, or caregiver is swinging the child by his or her
v v v v v v v v v v v v v
arms. Sometimes a pop may be heard, or clunk may be felt, usually followed by immediate crying.
v v v v v v v v v v v v v v v v
Children are generally consolable following the injury, and they often present with the arm held in a
v v v v v v v v v v v v v v v v v
neutral, extended, pronated position as this is generally the
v v v v v v v v v
position of best comfort. They will generally grimace or cry with palpation of the radial head. Diagnosis
v v v v v v v v v v v v v v v v
is clinical, and radiographs are seldom necessary; even if performed, they may not show misalignment
v v v v v v v v v v v v v v v
as this is a ligamentous injury and pediatric ossification of
v v v v v v v v v v
the elbow occurs between ages 2-12 years making the structures poorly visible on radiograph.
v v v v v v v v v v v v v
Treatment involves reducing the radial head back into the annulus through physical manipulation by
v v v v v v v v v v v v v v
hyper-pronation, supination-flexion maneuvers, or both. Seldom is
v v v v v v v
operative reduction necessary, nor is sedation to achieve appropriate reduction. A successful reduction
v v v v v v v v v v v v
is determined by the child reusing his or her arm. Recurrent injuries are common.
v v v v v v v v v v v v v v
Incorrect Answers: A, B, C, and D. v v v v v v
Dislocation of the shoulder (Choice A) would be uncommon following a traction maneuver on the arm.
v v v v v v v v v v v v v v v
Shoulder dislocation may result from abduction, extension, and rotation, or as a consequence of
v v v v v v v v v v v v v v
trauma or muscle spasm (such as in seizure or electrocution).
v v v v v v v v v v
Examination shows a flattened depression infe v v v v v
101
Exam Section 3: Item 1 of 50
v v v v v v
National Board of Medical Examiners' v v v v
Comprehensive Basic Science Self-Assessment v v v
100
1. A pharmaceutical company develops a new opioid drug (Drug X) that binds to the same receptor as
v v v v v v v v v v v v v v v v v
morphine does. Drug X is compared with morphine to test its analgesic effect. The graph shows the log
v v v v v v v v v v v v v v v v v v
dose-
v
response curves for morphine and Drug X. Based on these results, which of the following best describes
v v v v v v v v v v v v v v v v
Drug X?
v v
Morphine
A) Competitive antagonist
v v
B) Full agonist
v v
C) Inverse agonist
v v
Drug X v
2024/2025(Quiz bank with all the correct answers)(usmle step
1)Medical examination
1 Exam Section 1: Item 1 of 50
v v v v v v
National Board of Medical Examiners®
v v v v
Comprehensive Basic Science Self-Assessment v v v
1. Shortly after delivery, a full-term male newborn is found to have black hair with a white forelock. His
v v v v v v v v v v v v v v v v v v
mother, a brunette, also has a white forelock and wears hearing aids. Physical examination shows
v v v v v v v v v v v v v v v
heterochromia of irides. Otoacoustic emissions testing and
v v v v v v v
brain stem auditory evoked responses show bilateral sensorineural hearing loss. Which of the following
v v v v v v v v v v v v v
is the most likely cause of the findings in this patient?
v v v v v v v v v v v
A) Abnormal neural crest development
v v v v
B) Abnormality of connexins
v v v
C) Deficiency of homogentisic acid oxidase activity
v v v v v v
D) Deficiency of tyrosinase activity
v v v v
E) Failure of internalization of melanin granules by keratinocytes
v v v v v v v v
F) Failure of melanosome transportation along dendrites - ANSW -A.
v v v v v v v v v
Abnormal neural crest development leads to Waardenburg syndrome. Waardenburg syndrome is a
v v v v v v v v v v v
syndrome of patchy depigmentation of the skin, hair, irises, and cochlear dysfunction that primarily
v v v v v v v v v v v v v v
illustrates an autosomal dominant inheritance pattern. Because of
v v v v v v v v
genetic mutations of genes encoding transcription factors, neural crest cells do not properly
v v v v v v v v v v v v
differentiate into melanoblasts (melanocyte precursors), or melanoblasts do not migrate to their
v v v v v v v v v v v v
appropriate location. Patients typically have a white forelock and eyelashes,
v v v v v v v v v v
depigmented skin patches, iridic heterochromia, and sensorineural deafness. The eyes may also be
v v v v v v v v v v v v
laterally displaced. The clinical diagnosis may be confirmed with genetic testing. Treatment includes
v v v v v v v v v v v v v
audiologic evaluation and genetic consultation.
v v v v v
Incorrect Answers: B, C, D, E, and F.
v v v v v v v
An abnormality of connexins (Choice B) would lead to abnormal formation of the plasma membrane
v v v v v v v v v v v v v v
channels of diverse cell types. Different combinations of sensorineural hearing loss, ichthyosis,
v v v v v v v v v v v v
alopecia, and peripheral neuropathy may occur. Depigmentation
v v v v v v v
would be atypical. v v
,Deficiency of homogentisic acid oxidase activity (Choice C) would lead to decreased metabolism of the
v v v v v v v v v v v v v v
amino acids phenylalanine and tyrosine, which instead degrade into homogentisic acid. Homogentisic
v v v v v v v v v v v v
acid accumulates in the skin and joints, causing increased
v v v v v v v v v
pigmentation and arthritis, respectively. Depigmentation would be atypical. v v v v v v v
Deficiency of tyrosinase activity (Choice D) occurs in oculocutaneous albinism, which presents with
v v v v v v v v v v v v
uniformly hypopigmented hair and skin (versus the patchy depigmentation of Waardenburg syndrome)
v v v v v v v v v v v v
and eye abnormalities (eg, iris hypopigmentation, refractive
v v v v v v v
errors, nystagmus). In tyrosinase deficiency, melanocytes are unable to synthesize melanin from the
v v v v v v v v v v v v
amino acid tyrosine. Iridic heterochromia and sensorineural deafnes
v v v v v v v v
10
Exam Section 1: Item 10 of 50
v v v v v v
National Board of Medical Examiners® v v v v
Comprehensive Basic Science Self-Assessment v v v
10. A 12-year-old boy is brought to the physician by his parents because of bed-wetting. He urinates 10
v v v v v v v v v v v v v v v v v
to 15 times each day. He says that he is constantly thirsty and drinks large quantities of liquid
v v v v v v v v v v v v v v v v v v
throughout the day. Urinalysis shows a specific gravity of
v v v v v v v v v
1.003. A 24-hour urine collection shows a creatinine clearance of 140 mL/min, with a total urine volume
v v v v v v v v v v v v v v v v
of 7600 mL and urine osmolality of 230 mOsmol/kg H,O. A tumor affecting which of the following
v v v v v v v v v v v v v v v v v
hypothalamic nuclei is most likely involved in producing
v v v v v v v v
this patient's symptoms?
v v
A) Anterior
v
B) Arcuate
v
C) Dorsomedial
v
D) Lateral
v
E) Posterior
v
F) Supraoptic
v
G) Ventromedial - ANSW -F.
v v v v
Central diabetes insipidus may result from a tumor involving the hypothalamic paraventricular and
v v v v v v v v v v v v
supraoptic nuclei and is characterized by the inadequate secretion of antidiuretic hormone (ADH, also
v v v v v v v v v v v v v v
known as vasopressin) from the posterior pituitary. Normally,
v v v v v v v v
increased plasma osmolality will be sensed by osmoreceptors and result in the increased production of
v v v v v v v v v v v v v v
vvasopressin in the hypothalamic paraventricular and supraoptic nuclei. Vasopressin is subsequently
v v v v v v v v v v
vreleased by the posterior pituitary gland. ADH binds V2
v v v v v v v v
,receptors of the late distal convoluted tubule and the collecting duct principal cells, which results in the
v v v v v v v v v v v v v v v v
insertion of aquaporin channels in the luminal surface and increases free water absorption. This
v v v v v v v v v v v v v v
process is typically utilized to maintain tight regulation of the
v v v v v v v v v v
serum osmolality. Inadequate production of ADH by the hypothalamus and release by the posterior
v v v v v v v v v v v v v
pituitary gland may occur in the setting of various pathologies, such as pituitary tumors, trauma,
v v v v v v v v v v v v v v v
tuberculosis, or intracranial surgery. This results in a decreased
v v v v v v v v v
ability to absorb adequate amounts of free water within the collecting duct, which results in dilute
v v v v v v v v v v v v v v v
urine and increased serum osmolality. Patients typically present with extreme thirst, production of
v v v v v v v v v v v v v
large volumes of dilute urine, and altered mental status. Treatment
v v v v v v v v v v
requires the administration of desmopressin, an analog of vasopressin (ADH), which results in the
v v v v v v v v v v v v v
reabsorption of free water via aquaporin insertion in the collecting duct.
v v v v v v v v v v v
Incorrect Answers: A, B, C, D, E, and G.v v v v v v v v
The anterior hypothalamic nucleus (Choice A) is involved in thermoregulation, specifically in cooling.
v v v v v v v v v v v v
The arcuate hypothalamic nucleus (Choice B) contains complex regulatory functions that are involved in
v v v v v v v v v v v v v
appetite stimulation.
v v
The dorsomedial hypothalamic nucleus (Choice C) is involved in the regulation of fe
v v v v v v v v v v v v
100
Exam Section 2: Item 50 of 50
v v v v v v
National Board of Medical Examiners®v v v v
Comprehensive Basic Science Self-Assessment v v v
50. A 16-month-old girl is brought to the physician because she has refused to move her right arm since
v v v v v v v v v v v v v v v v v v
her older brother grabbed her right hand 1 hour ago to stop her from running into the street. On
v v v v v v v v v v v v v v v v v v v
examination, she is holding the right arm in pronation. Any
v v v v v v v v v v
motion of the right elbow produces pain. There is no visible edema. Which of the following is the most
v v v v v v v v v v v v v v v v v v
likely explanation for these findings?
v v v v v
A) Dislocation of the shoulder
v v v v
B) Fracture of the distal radius and ulna
v v v v v v v
C) Salter-Harris type I fracture of the humerus
v v v v v v v
D) Septic arthritis
v v
E) Subluxation of the radial head - ANSW -E.
v v v v v v v v
Dislocation or subluxation of the radial head is a common pediatric injury, known as a nursemaid
v v v v v v v v v v v v v v v
elbow. It results from traction on the radial head, which displaces it from within its ligamentous
v v v v v v v v v v v v v v v v
annulus. This most often occurs in children of age 12-36 months, and
v v v v v v v v v v v v
, often arises from defensive maneuvers by parents or caretakers when grabbing the child's arm to
v v v v v v v v v v v v v v
prevent running into traffic or similarly endangering oneself. It can also arise from routine play if a
v v v v v v v v v v v v v v v v v
parent, older sibling, or caregiver is swinging the child by his or her
v v v v v v v v v v v v v
arms. Sometimes a pop may be heard, or clunk may be felt, usually followed by immediate crying.
v v v v v v v v v v v v v v v v
Children are generally consolable following the injury, and they often present with the arm held in a
v v v v v v v v v v v v v v v v v
neutral, extended, pronated position as this is generally the
v v v v v v v v v
position of best comfort. They will generally grimace or cry with palpation of the radial head. Diagnosis
v v v v v v v v v v v v v v v v
is clinical, and radiographs are seldom necessary; even if performed, they may not show misalignment
v v v v v v v v v v v v v v v
as this is a ligamentous injury and pediatric ossification of
v v v v v v v v v v
the elbow occurs between ages 2-12 years making the structures poorly visible on radiograph.
v v v v v v v v v v v v v
Treatment involves reducing the radial head back into the annulus through physical manipulation by
v v v v v v v v v v v v v v
hyper-pronation, supination-flexion maneuvers, or both. Seldom is
v v v v v v v
operative reduction necessary, nor is sedation to achieve appropriate reduction. A successful reduction
v v v v v v v v v v v v
is determined by the child reusing his or her arm. Recurrent injuries are common.
v v v v v v v v v v v v v v
Incorrect Answers: A, B, C, and D. v v v v v v
Dislocation of the shoulder (Choice A) would be uncommon following a traction maneuver on the arm.
v v v v v v v v v v v v v v v
Shoulder dislocation may result from abduction, extension, and rotation, or as a consequence of
v v v v v v v v v v v v v v
trauma or muscle spasm (such as in seizure or electrocution).
v v v v v v v v v v
Examination shows a flattened depression infe v v v v v
101
Exam Section 3: Item 1 of 50
v v v v v v
National Board of Medical Examiners' v v v v
Comprehensive Basic Science Self-Assessment v v v
100
1. A pharmaceutical company develops a new opioid drug (Drug X) that binds to the same receptor as
v v v v v v v v v v v v v v v v v
morphine does. Drug X is compared with morphine to test its analgesic effect. The graph shows the log
v v v v v v v v v v v v v v v v v v
dose-
v
response curves for morphine and Drug X. Based on these results, which of the following best describes
v v v v v v v v v v v v v v v v
Drug X?
v v
Morphine
A) Competitive antagonist
v v
B) Full agonist
v v
C) Inverse agonist
v v
Drug X v
