10 USMLE Step 1 Mixed Review Questions with Answers (Set 2)

These 10 quick USMLE review questions test the high-yield facts that show up again and again on the exam: lymphocytosis, asthma exacerbation, cri-du-chat, seborrheic keratosis, relative risk, pityriasis rosea, contact dermatitis, cystic fibrosis, cellulitis and epididymitis. 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 these conditions is most likely associated with peripheral lymphocytosis?

A- Inflammatory bowel disease
B- Myocardial infarction
C- Pyogenic bacterial infections
D- Viral hepatitis

D-Viral hepatitis
The correct answer is D

 

Question 2. Which test of the following is used to evaluate acute exacerbation of asthma?

A- Chest x-ray
B- Complete blood count
C- Pulse oximetry
D- Peak expiratory flow rate (PEFR)

D- Peak expiratory flow rate (PEFR)- Peak flow (or FEV1) objectively measures how severe the airflow obstruction is and how well it responds to treatment. Pulse oximetry is also checked to assess oxygenation, but it does not measure airflow. A chest x-ray is only needed if pneumonia or pneumothorax is suspected.
The correct answer is D

 

Question 3. What is the genetic abnormality related to Cri-du-chat-syndrome?

A- Deletion of phenylalanine in position 508
B- Deletion of short arm of chromosome 5
C- Mutations of the fibrillin gene on chromosome 15
D- Trisomy 18

B- Deletion of short arm of chromosome 5
The correct answer is B

 

Question 4. Which of the following is an epithelial tumor with a “stuck-on” appearance?

A- Actinic keratosis
B- Basal cell carcinoma
C- Seborrheic keratosis
D- Squamous cell carcinoma

C- Seborrheic keratosis
The correct answer is C

 

Question 5. Which of the following is calculated by dividing the incidence rate of a disease in exposed by the incident rate of unexposed?

A- Attributable risk
B- Odds ratio
C- Positive predictive value
D- Relative risk

D- Relative risk- Relative risk = incidence in the exposed ÷ incidence in the unexposed (from cohort studies). Attributable risk is the DIFFERENCE between the two incidence rates. The odds ratio is used in case-control studies.
The correct answer is D

 

Question 6. Which one of the following dermatologic disorders presents with a herald patch and a Christmas tree pattern?

A- Bullous pemphigoid
B- Pemphigus vulgaris
C- Pityriasis rosea
D- Psoriasis

C- Pityriasis rosea
The correct answer is C

 

Question 7. Which one of the following metals is the most likely cause of allergic contact dermatitis, especially in females?

A- Copper
B- Gold
C- Nickel
D- Silver

C- Nickel
The correct answer is C

 

Question 8. Which of the following is the mode of inheritance of cystic fibrosis?

A- Autosomal dominant
B- Autosomal recessive
C- X-linked dominant
D- X-linked recessive

B- Autosomal recessive
The correct answer is B

 

Question 9. A diabetic patient with a history of MRSA infection develops purulent cellulitis of the leg with fever and needs hospital admission. Which one of the following antibiotics is the most appropriate empiric treatment?

A- Amoxicillin
B- Imipenem
C- Neomycin
D- Vancomycin

D- Vancomycin- IV vancomycin covers MRSA, which is likely in purulent cellulitis and in patients with prior MRSA infection. For simple non-purulent cellulitis without MRSA risk, a beta-lactam such as cefazolin or cephalexin (covering streptococci) is usually enough.
The correct answer is D

 

Question 10. Which of the following is the most common causative organism of epididymitis in elderly patients?

A- Chlamydia
B- E-Coli
C- Gonococci
D- Streptococci

B- E-Coli- In elderly patients, epididymitis is most commonly caused by enteric bacteria, with E. coli being the most frequent pathogen. This is in contrast to younger, sexually active men, where sexually transmitted pathogens like Chlamydia trachomatis and Neisseria gonorrhoeae are more common causes.
The correct answer is B

 

High-yield points from this set

  • Cri-du-chat = deletion of the short arm of chromosome 5.
  • Relative risk = incidence in exposed ÷ incidence in unexposed.
  • A herald patch followed by a “Christmas tree” rash = pityriasis rosea.
  • Nickel is the most common cause of allergic contact dermatitis.

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