USMLE Practice Questions
Prepare for USMLE with more than an answer.
- Level
- Professional Licensure
- Valid for
- permanent
- 1
A 38-year-old patient with sleep disorders undergoes polysomnography. The sleep technician notes that the patient experiences rapid eye movement (REM) episodes at predictable intervals throughout the night. Based on normal sleep architecture, approximately how frequently do these REM cycles occur?
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Correct answer: A
REM sleep cycles occur approximately every 90 minutes throughout the night as part of the ultradian rhythm. A complete sleep cycle includes stages N1, N2, N3 (non-REM), and REM sleep, lasting about 90-110 minutes total. Adults typically experience 4-6 complete sleep cycles per night, with REM periods becoming longer and more frequent toward morning. This 90-minute periodicity is fundamental to normal sleep architecture.
- 2
During a newborn examination in the delivery room, a pediatrician tests various primitive reflexes. The physician gently strokes the lateral aspect of the infant's foot from heel to toe, observing that the great toe extends upward while the other toes fan out. Which of the following reflexes would NOT be expected to be present at birth in a healthy full-term newborn?
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Correct answer: A
The parachute reflex (protective extension) is NOT present at birth but develops around 8-10 months of age. When an infant is held horizontally and suddenly moved toward a surface, they extend their arms to protect themselves from falling. In contrast, Babinski, palmar grasp, and Moro reflexes are all primitive reflexes present at birth. The described scenario shows a positive Babinski reflex, which is normal in newborns until approximately 12-24 months of age.
- 3
During a pediatric developmental assessment, a mother describes her 30-month-old daughter's play behavior: 'She likes to play near other children at the playground but doesn't really interact with them. She'll do similar activities like digging in the sandbox while other kids are doing the same thing, but each child is focused on their own play.' Which developmental milestone does this behavior pattern represent?
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Correct answer: D
Parallel play typically emerges between 24-48 months and is characterized by children playing alongside each other with similar materials or activities but without significant interaction or shared goals. The 30-month-old's behavior of playing near other children in the sandbox while remaining focused on her own activity exemplifies classic parallel play. This developmental stage precedes associative and cooperative play, representing normal social development for toddlers.
- 4
A 32-year-old woman presents to the emergency department 3 days after the sudden death of her spouse in a motor vehicle accident. She tells the physician, 'This isn't real. He's just away on a business trip and will be home tomorrow.' She appears calm and shows no signs of emotional distress. Which stage of the grief process is this patient most likely experiencing?
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Correct answer: B
Denial is the first stage of the Kübler-Ross grief model, characterized by the inability to accept the reality of loss. The patient's statement that 'This isn't real' and belief that her spouse will return demonstrates classic denial behavior. This defense mechanism temporarily shields the individual from the overwhelming reality of the loss, allowing psychological protection while the mind begins to process the trauma.
- 5
A 28-year-old medical student with a history of poor academic performance in anatomy consistently excels in clinical skills and patient communication. When discussing his struggles with basic sciences, he frequently emphasizes his strong bedside manner and states, 'I may not be great with memorization, but I really connect with patients.' Which psychological defense mechanism is this student demonstrating?
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Correct answer: C
Compensation is a defense mechanism where an individual covers up perceived weaknesses by emphasizing strengths or achievements in other areas. The medical student acknowledges his weakness in anatomy but consistently highlights his superior clinical and communication skills to offset this deficiency. This adaptive mechanism helps maintain self-esteem while addressing areas of inadequacy.
- 6
A 45-year-old executive with insomnia undergoes polysomnography. The sleep study reveals predominant theta waves (4-8 Hz) during sleep onset and frequent awakenings throughout the night. The patient reports feeling unrested despite spending 8 hours in bed. Which characteristic is most commonly associated with individuals who experience frequent sleep disruptions like this patient?
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Correct answer: B
Theta waves (4-8 Hz) are characteristic of light sleep stages (N1) and are predominant in individuals who are light sleepers or have frequent sleep disruptions. Light sleepers spend more time in theta wave-dominated stages and less time in deeper delta wave sleep, leading to frequent awakenings and poor sleep quality. This explains the patient's unrested feeling despite adequate time in bed.
