10 USMLE Step 1 Mixed Review Questions with Answers (Set 3)

These 10 quick USMLE review questions test the high-yield facts that show up again and again on the exam: vitiligo, catheter oliguria, acid-base disorders, neck masses, greenstick fractures, otitis media, cephalohematoma, exocytosis, the Apgar score and prevalence. Each question includes the correct answer.

Written by Dr. Ray Makar, MD, author of the Repeated USMLE Questions eBook series.

Prefer video? Watch daily USMLE case questions on MedFocus by Dr. Ray on YouTube.

How to use this page: read the question, pick your answer, then tap Show Answer and Explanation.

Questions

Question 1. Which one of the following is the most common cause of vitiligo?

A- Autoimmune
B- Chemical
C- Infection
D- Trauma

A- Autoimmune- Vitiligo is most commonly caused by an autoimmune process where the body’s immune system attacks the melanocytes, the cells responsible for producing skin pigment.
The correct answer is A

 

Question 2. Which of the following is the next step to investigate oliguria in a catheterized patient?

A- Irrigate the catheter
B- Measure serum creatinine
C- Measure urine specific gravity
D- Start intravenous fluids

A- Irrigate the catheter
The correct answer is A

 

Question 3. Which of the following is the most common primary disturbance of acid-base balance in pregnant women?

A- Metabolic acidosis
B- Metabolic alkalosis
C- Respiratory acidosis
D- Respiratory alkalosis

D- Respiratory alkalosis
The correct answer is D

 

Question 4. A patient presents with a neck mass. Which of the following suggests the possibility of cancer?

A- History of hoarseness of voice for 3 months
B- History of hypothyroidism
C- Pain or tenderness
D- Recent complaint of toothache

A- History of hoarseness of voice for 3 months
The correct answer is A

 

Question 5. Which one of the following fractures is incomplete and involving the cortex of only one side of the bone?

A- Greenstick fracture
B- Nursemaid’s elbow
C- Osgood-Schlatter disease
D- Torus fracture

A- Greenstick fracture
The correct answer is A

 

Question 6. Which of the following is the most common complication of otitis media?

A- Brain abscess
B- Drum perforation
C- Hearing loss
D- Meningitis

C- Hearing loss- The most common complication of otitis media is conductive hearing loss, usually temporary due to fluid buildup in the middle ear.Drum perforation, meningitis, and brain abscess are less common and occur in more severe or untreated cases.
The correct answer is C

 

Question 7. Which of the following characteristics differentiates cephalohematoma from caput succedaneum in a newborn?

A- Cephalohematoma crosses suture lines
B- Cephalohematoma does not cross suture lines
C- Cephalohematoma disappears in the first few days
D- Cephalohematoma will never calcify

B- Cephalohematoma does not cross suture lines- A cephalohematoma is a subperiosteal hemorrhage that is limited by suture lines, so it does NOT cross them.In contrast, caput succedaneum is subcutaneous edema that can cross suture lines and resolves quickly.
The correct answer is B

 

Question 8. Which one of the following types of cell secretions involves exocytosis?

A- Apocrine secretion
B- Holocrine secretion
C- Merocrine secretion

C- Merocrine secretion- Merocrine secretion releases its products by exocytosis without any loss of cellular material. Apocrine secretes part of the cell’s apex, and holocrine secretion involves complete cell rupture.
The correct answer is C

 

Question 9. Which one of the following is NOT a factor in the Apgar Scoring System?

A- Heart rate
B- Reflex irritability
C- Respiration
D- Skull dimensions

D- Skull dimensions
The correct answer is D

 

Question 10. If a new effective treatment for COVID-19 is initiated, which of the following will be the appropriate effect on incidence and prevalence?

A- Both incidence and prevalence increase
B- Incidence decreases with no change in prevalence
C- No change in both
D- No current change in incidence and reduced prevalence

D- No change in current incidence and decreased prevalence- A new effective treatment does not prevent new cases, so incidence does not change. However, it shortens the duration of illness by helping patients recover faster, which reduces prevalence.
The correct answer is D

 

High-yield points from this set

  • Oliguria with a urinary catheter: first irrigate or flush the catheter.
  • Greenstick fractures are incomplete fractures in children.
  • A cephalohematoma does not cross suture lines; caput succedaneum does.
  • An effective treatment that cures a disease lowers its prevalence but does not change its incidence.

Keep practicing

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