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

These 10 mixed USMLE Step 1 review questions jump between subjects, just like the real exam: neuroanatomy, Horner syndrome, ophthalmic shingles, endocrine skin signs, acromegaly, achalasia, infertility, psychological defense mechanisms and hepatitis A. Each question includes the correct answer and an explanation.

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. A 28-year-old man has a minor injury as a result of motor car accident. He complains of severe pain due to a scratch on his scalp across the front hairline. Which one of these nerves is related to this pain?

A- Trigeminal nerve
B- Facial nerve
C- Vagus nerve
D- Oculomotor nerve
E- Orbital nerve

The anterior scalp at this area is innervated by the ophthalmic branch of trigeminal nerve.
The correct answer is A

 

Question 2. A 23-year-old woman presents to her physician with ptosis, miosis and anhidrosis on the left side of her face. Which one of the following drugs is used as an eye-drop test to confirm the diagnosis of this condition?

A- Albuterol
B- Atenolol
C- Cocaine
D- Epinephrine
E- Phenylephrine

C- Cocaine- This is Horner syndrome (loss of sympathetic supply to the eye). Cocaine blocks norepinephrine reuptake at the nerve ending. A normal pupil dilates, but a Horner pupil dilates poorly because little norepinephrine is being released, which confirms the diagnosis (apraclonidine is now often used instead). To tell a preganglionic from a postganglionic lesion, hydroxyamphetamine is used: it dilates the pupil only if the postganglionic neuron is intact.
The correct answer is C

 

Question 3. A 35-year-old woman presents with troubled vision and severe pain in her left eye. She has been diagnosed with shingles on the left side of her face and the cornea of her left eye. Which of these nerves is the most likely affected in this patient?

A- Optic nerve
B- Oculomotor nerve
C- Trigeminal nerve
D- Facial nerve

The most likely affected nerve in this patient is the trigeminal nerve (CN V). Infection of Varicella virus starts on the face and travels through trigeminal nerve to the cornea causing trouble of vision and severe pain.
The correct answer is C

 

Question 4. Which one of the following conditions is associated with Acanthosis Nigricans?

A- Amyloidosis
B- Diabetes insipidus
C- Diabetes mellitus
D- Hemochromatosis

C- Diabetes mellitus- Acanthosis nigricans is a skin condition characterized by areas of dark, thickened, and velvety skin, typically occurring in body folds and creases such as the neck, armpits, groin, and joints. In diabetes type 2, the high levels of insulin in the bloodstream can stimulate the growth of skin cells and increase the production of skin pigment, resulting in the characteristic darkening and thickening of the skin seen in acanthosis nigricans. It can also occur in other conditions such as obesity, hormonal disorders, and certain medications.
The correct answer is C

 

Question 5. Which one of the following complications is the common cause of death in acromegaly?

A- Heart failure
B- Hepatic failure
C- Splenic infarction
D- Renal failure

A- Heart failure- In acromegaly, the common cause of death is typically heart failure. This is because the excess growth hormone and insulin-like growth factor-1 produced in acromegaly can lead to cardiovascular complications, such as hypertension and cardiomyopathy, which can progress to heart failure over time. Therefore, monitoring and managing cardiovascular health are crucial aspects of treating patients with acromegaly.
The correct answer is A

 

Question 6. Achalasia is a motility disorder of the esophagus characterized by impaired relaxation of the lower esophageal sphincter. Which of the following is the most likely etiology of this condition?

A- Adenocarcinoma of the lower esophagus
B- Degeneration of the inhibitory neurons of the myenteric plexus
C- Obstruction caused by Schatzki rings
D- Prolonged intubation

B- Degeneration of the inhibitory neurons of the myenteric plexus- This is a straight question and you can figure out the correct answer out of the scenario as it is the case in some of USMLE Step 1 questions. It is a motility disorder and the only option to match it is B which mentions myenteric plexus (muscle control).
The correct answer is B

 

Question 7. Which of the following is the most common cause of infertility in women in the United States of America?

A- Congenital adrenal hyperplasia
B- Pelvic inflammatory disease
C- Polycystic ovarian syndrome
D- Uterine fibroids

C- Polycystic ovarian syndrome- It has a prevalence of 6-10% among women of reproductive age in USA. It is the leading cause of infertility.
The correct answer is C

 

Question 8. A student’s aggression towards his family is redirected to get straight A’s in school. Which of the following defense mechanisms explains this action?

A- Altruism
B- Humor
C- Sublimation
D- Suppression

C- Sublimation- It is replacing unacceptable action with another course of action that does not conflict with the person’s value system.
The correct answer is C

 

Question 9. A 72-year-old man presents to his physician for a follow up after a stroke. The physician pays more attention for the care of this patient, as he reminds the physician of his father who passed away 3 years ago after having a stroke. This is an example of which one of these mechanisms?

A- Acting out
B- Displacement
C- Projection
D- Transference
E- Countertransference

This is an example of countertransference, which is redirection of the physician’s feeling toward his patient. It is opposite to transference, which is redirection of the patient’s feeling of a significant person to the physician. Other options have different definitions.
The correct answer is E

 

Question 10. An 18-year-old male complains of nausea and slight icterus for 2 weeks. Medical, surgical and family histories are unremarkable. Physical examination reveals slight jaundice and tenderness on the right upper side of the abdomen. Laboratory findings include positive IgM anti-HAV and marked elevation of ALT and AST levels. What is the appropriate management of this patient at this time?

A- Acyclovir
B- Famciclovir
C- HBV vaccine
D- Interferon alfa
E- Supportive treatment

This is a 2-step question which is common in USMLE and other board examinations. The first step is to find the diagnosis which is viral hepatitis A, confirmed by positive IgM anti-HAV. The other step is management which is supportive treatment. Acute hepatitis A is a self-limited disease and complete recovery occurs in most patients. Other answer choices are not treatment options for acute hepatitis A infection.
The correct answer is E

 

High-yield points from this set

  • The forehead and anterior scalp are supplied by V1 (supraorbital and supratrochlear nerves).
  • Ptosis, miosis and anhidrosis = Horner syndrome; cocaine or apraclonidine drops confirm it.
  • Shingles of the forehead and cornea = herpes zoster ophthalmicus (V1).
  • Acanthosis nigricans signals insulin resistance (or rarely gastric cancer).
  • Heart failure is the most common cause of death in acromegaly.
  • Achalasia = loss of inhibitory neurons of the myenteric plexus.
  • PCOS is the most common cause of female infertility.
  • Channeling unacceptable impulses into acceptable activities = sublimation.
  • The physician’s feelings toward a patient = countertransference.
  • Acute hepatitis A is treated supportively.

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