USMLE Immunology Questions
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A family who recently moved from Nebraska to Texas visits the pediatrician. They have one 3-year-old child that had been developing normally prior to this. Three months after having moved to the new house, the child became lethargic, fatigued, pale and has been suffering from constipation. Sideroblasts are found in his blood smear. Analyze the scheme below. Which of the following is enzyme labeled as no. 1 that is impaired in this patient and causing his symptoms?
  1. Ribonuclease
  2. Ferrochelatase
  3. ALA oxidase
  4. Uroporphyrinogen decarboxylase
  5. Uroporphyrin I
Pathology USMLE Step 1 Sample Question Image: by Lecturio
A 49-year-old male, with a history of alcohol abuse over the last two decades, presents with the complaint of epigastric pain for a year or so. He previously had one episode of acute pancreatitis for which he was hospitalized. He continued to drink 4–5 beers/day after he was discharged. His appetite is good but gives history of weight loss. He also complaints of oily bulky stools. He takes aluminium hydroxide gel and ranitidine to get partial pain relief. Vitals were stable. Routine physical exam and blood work are normal except for mild hypocalcemia. Abdominal CT is provided here. Which of the following tests is comparatively less useful in this condition to assess the organ’s function?
  1. Secretin stimulation test
  2. Serum amylase and lipase
  3. Serum trypsin level
  4. Fecal elastase
  5. Magnetic resonance cholangiopancreatography (MRCP)
Pathology USMLE Step 1 Sample Question - Gastro Image: by Hellerhoff, License: CC BY-SA 3.0
A medical student in reviewing dose-response curves of various experimental drugs. She is specifically interested in the different factors that cause the curve to shift in different directions. From her study, she plots the following graph. She marks the blue curve for drug A which acts optimally on a receptor. After drawing the second curve, she discovers that this drug has a lower ability to produce a reaction than the first one. She also discovers that more of the second drug B is required to produce the same response as the first one. Which of the following attributes best describes the activity of drug B in comparison to drug A?
  1. Lower potency
  2. Higher efficacy
  3. Higher potency
  4. Increased affinity
  5. Decreased efficacy
Pharmacology USMLE Step 1 Sample Question Image: Hypothetical dose-responses. By Pronchik, License: CC BY-SA 3.0
A 7-year-old boy is brought to the clinic by his parents due to right ear pain. For the past few days, he has had a low-grade fever, a runny nose and has been pulling his left ear frequently. He is up-to-date on all vaccinations and is doing good at school. His temperature is 38.5°C (101.3°F), blood pressure is 106/75 mm Hg, pulse is 101/min and respirations are 20/min. Finding of otoscopic examination is shown in the image. One month ago he had a similar episode for which he was prescribed amoxicillin for 10 days. This time the doctor decides to prescribe him amoxicillin with clavulanic acid. Which of the following best describes the benefit of adding clavulanic acid to amoxicillin?
  1. Tachyphylactic effect
  2. Inhibitor effect
  3. Additive effect
  4. Permissive effect
  5. Synergistic effect
Pharmacology USMLE Step 1 Practice Question Image: By B. Welleschik, License: CC BY-SA 3.0
A 36-year-old man undergoes ileocecal resection for a gunshot injury. Resected ileocecal segment is sent for histological evaluation. One of the slides derived from the specimen is shown in the picture below. Which of the following statements regarding the structure marked with the red circle is correct?
  1. This structure can be only found in the colon.
  2. This structure can become a site of entry of certain microorganisms including S. typhi.
  3. Infants have the largest amount of these structures within their intestinal wall.
  4. This structure only appears in case of bacterial infection.
  5. These structures mostly contain M-cells.
Histology USMLE Step 1 Practice Question Image: By Plainpaper, License: CC BY-SA 3.0
A 60-year-old female is brought to the clinic by her husband for evaluation of snoring. According to her husband, her snoring has increased over the last year and he can’t tolerate it at anymore. He has also noticed that she wakes up at night regularly for a few seconds but then falls back asleep. During the day she is sleepy most of the time and complains of headaches and poor concentration. Her other medical problems include hypertension and hyperlipidemia. Her temperature is 36.6°C (97.9°F), blood pressure 156/98 mmHg, pulse is 90/min and respirations are 20/min. Her body mass index (BMI) is 38 kg/m2. A polysomnographic study is ordered the result of which is given below. While counseling the patient about her condition and available treatment options, she is asked if she wants to try a new therapy in which a device stimulates one of her cranial nerves. Which of the following muscles will be stimulated by this method?
  1. Genioglossus muscle
  2. Digastric muscle
  3. Hyoglossus muscle
  4. Palatoglossus muscle
  5. Intercostal muscles
Anatomy USMLE Step 1 Practice Question Image: by Lecturio
To study the flow of blood in the systemic circulation, partially occlusive stents are placed in the pulmonary trunk of a physiological system that mimics human physiology while the pressure in his right atrium is monitored. A graph where the right atrial pressure is a function of venous return is plotted. Assuming all circulatory nerve reflexes are absent in the system, at what point on the diagram shown below will his arterial pressure be closest to the venous pressure?
  1. Point I
  2. Point II
  3. Point III
  4. Point IV
  5. Point V
Physiology USMLE Step 1 Practice Question Image: by Lecturio
A husband and wife consult a geneticist after they have lost one child recently. They both lead a normal life, have normal intellectual abilities but are dwarves. One of their children is a dwarf as well and has difficulty in moving and performing physical activities. The displayed pedigree is drawn, and considers the severity of the proposed skeletal disorder. There is missing data regarding the first generation. The geneticist also consults with the biochemistry department to test for a common mutation which may likely explain the etiology. Which of the following would be the best interpretation of this pedigree?
  1. All members of the second generation are compound heterozygotes
  2. One half of the children are unaffected
  3. The penetrance of this disorder can be described as incomplete
  4. The disorder is likely completely dominant
  5. There is a 50% chance of having an affected offspring for this family
Medical Genetics USMLE Step 1 Practice Question Image: by Lecturio
A 60-year-old male presents to the clinic with his wife for “weird breathing” during the night. The wife says that her husband’s breathing pattern is irregular but he does not snore. The patient does is not aware of these symptoms. He has never had any issues with his health in the past. He spends a night at the sleep lab where his tidal volume is monitored overnight and tracing shown in the picture is recorded. Which of the following is most likely responsible for his breathing pattern?
  1. Diabetic ketoacidosis
  2. Heroin abuse
  3. Hypothyroidism
  4. Left ventricular heart failure
  5. Obesity
Physiology USMLE Step 1 Sample Question Image: by Lecturio
A 4-year-old male is brought to the clinic with complaints of flu-like symptoms and chest pain for 3-day duration. The mother states that he felt warm to the touch as well as developing chest and muscle pain within the past week but was hesitant to prescribe any medications. She confirms that all pediatric vaccinations were given at the appropriate times. Current temperature is 38.8°C (102.0°F), pulse 90/minute, blood pressure 102/64 and respirations 26/minute. Biopsy of the heart demonstrates the image. In which subclass is the offending virus most likely found?
  1. Herpesvirus
  2. Parvovirus
  3. Enterovirus
  4. Togavirus
  5. Flavivirus
Pathology USMLE Step 1 Practice Question Image: by BellRap, License: CC BY-SA 3.0

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