Molecular Biology/Genetics USMLE Step 1 Practice Questions
58 board-style USMLE Step 1 questions in Biochemistry. Each question shows the correct answer; create a free account for the full explanation and adaptive practice.
- USMLE Step 1 · medium · image1. An investigator is developing a new vaccine. Eukaryote ribosomes are utilized to create a novel protein. After the aminoacyl-tRNA binds to the A site, which of the following is…
- USMLE Step 1 · medium2. An investigator studying protein synthesis in human stem cells isolates tRNA molecules bound to mRNA molecules. The isolated tRNA molecules have inosine in the 5' position of th…
- USMLE Step 1 · medium3. A 9-year-old boy is brought to his pediatrician by his parents who report that he has had difficulty maintaining academic performance despite previous normal development. On exa…
- USMLE Step 1 · medium4. A 31-year-old woman presents with abnormal cervical cytology. Vital signs are normal (BP 118/76, HR 82, RR 16, Temp 37°C, SpO2 98%). Cervical biopsy demonstrates high-grade squa…
- USMLE Step 1 · hard5. A 45-year-old kidney transplant recipient on tacrolimus and mycophenolate presents with fever (38.9°C), malaise, and floaters with hemorrhagic retinitis on fundoscopy. Labs show…
- USMLE Step 1 · hard6. A newborn presents with severe lymphopenia (WBC 2,800/μL, lymphocytes 8%) discovered on routine screening after an older sibling died from Pneumocystis jirovecii pneumonia at 6…
- USMLE Step 1 · easy7. A 19-year-old man presents with recurrent bacterial infections and impaired wound healing. Vital signs show BP 118/76 mmHg, HR 88/min, RR 16/min, temp 37.2°C, SpO2 98%. Laborato…
- USMLE Step 1 · hard8. A 58-year-old woman with a newly diagnosed breast cancer presents with a palpable 2.5-cm mass. Vital signs show BP 128/82, HR 92, RR 16, Temp 37.1°C, SpO2 98%. Tumor biopsy reve…
- USMLE Step 1 · medium9. A 58-year-old man with newly diagnosed acute myeloid leukemia presents with fatigue, petechiae, and bleeding gums. Laboratory studies show WBC 87,000/μL and hemoglobin 7.2 g/dL.…
- USMLE Step 1 · hard10. A 2-year-old girl presents with global developmental delay, intellectual disability, and multiple congenital anomalies including cardiac defects. Vital signs are stable (BP 95/6…
- USMLE Step 1 · medium11. A researcher studying metastatic breast cancer cells measures gene expression at multiple levels. She obtains tumor tissue samples and determines messenger RNA levels of HER2 re…
- USMLE Step 1 · medium12. A 26-year-old woman presents with fever (38.9°C), myalgias, and nonproductive cough during a novel RNA respiratory virus outbreak. Vital signs show HR 102 bpm, RR 20/min, BP 118…
- USMLE Step 1 · medium13. A 28-year-old woman delivers an infant with hypotonia, upslanting palpebral fissures, and a single palmar crease. Vital signs show HR 120/min, RR 28/min, and mild hypothermia at…
- USMLE Step 1 · easy14. A 7-year-old boy presents with declining school performance and behavioral difficulties. Vital signs are normal (BP 110/68, HR 82, RR 20, Temp 37°C). Examination reveals a long…
- USMLE Step 1 · medium15. A 5-year-old girl presents with severe intellectual disability, ataxic gait, unprovoked frequent laughter, and recurrent seizures. Vital signs are stable (BP 95/60, HR 88, RR 20…
- USMLE Step 1 · medium16. A 3-year-old boy presents with hyperphagia, rapid weight gain despite normal appetite regulation attempts, hypotonia, and small hands and feet. He has moderate developmental del…
- USMLE Step 1 · medium17. A 2-month-old male infant presents with hypotonia, poor feeding, and seizures. Vital signs show HR 145 bpm, RR 38, BP 72/48, temperature 37.2°C, and SpO2 98% on room air. Physic…
- USMLE Step 1 · medium18. A 17-year-old girl presents to the emergency department with fever (39.2°C), tachypnea (RR 28), and tachycardia (HR 112). She reports ingesting a large quantity of aspirin 2 hou…
- USMLE Step 1 · medium19. A 58-year-old man with newly diagnosed pancreatic adenocarcinoma (T3N1M0) undergoes treatment with gemcitabine. Vital signs are stable: BP 128/82 mmHg, HR 92/min, RR 16/min, Tem…
- USMLE Step 1 · medium20. A 29-year-old woman with family history of Huntington disease presents for genetic screening. Vital signs are stable (BP 118/76, HR 72, RR 14, Temp 37°C). She reports no current…
- USMLE Step 1 · hard21. A 42-year-old woman presents with vaginal bleeding and is diagnosed with endometrial adenocarcinoma. Vital signs are stable (BP 128/82, HR 78). Her father had colon cancer at ag…
- USMLE Step 1 · medium22. An 8-year-old boy presents with severe photosensitivity and multiple freckle-like pigmented lesions on sun-exposed areas. Vital signs are normal; however, he has already undergo…
- USMLE Step 1 · hard23. A 34 year old woman seeks counseling because her father developed gait instability and choreiform movements in middle age. Genetic testing in the family identified a CAG trinucl…
- USMLE Step 1 · hard24. A 19 year old woman presents with episodic muscle weakness and exercise intolerance. She has a history of sensorineural hearing loss and migraine like headaches. Her mother and…