Practice Test 1 - USMLE Step 1

20 questions. Answer them in any order, then submit to see your score and every explanation.

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1. Which of the following cell types is most critical for eliminating host cells that have downregulated surface expression of MHC class I molecules?
2. p53 carries out its pro-apoptotic function primarily by acting as a transcription factor for which of the following target genes?
3. The therapeutic effect of the medication responsible for this reaction is achieved by which of the following mechanisms?
4. Which of the following best describes the immunological rationale for this combined post-exposure prophylaxis strategy?
5. The surge of which of the following hormones is directly responsible for triggering ovulation within 24-36 hours?
6. The progressive renal damage in this patient is primarily due to which of the following processes?
7. In the absence of the SRY gene product, which of the following developmental events occurs in a 46,XX fetus?
8. Which of the following patterns of histone modification is most consistent with the condensed chromatin state and silencing of the MLH1 gene?
9. The patient's asplenic state primarily increases her susceptibility to this type of infection due to which of the following?
10. The infant's protection from measles in this scenario is best explained by which of the following principles?
11. Which of the following is the most likely mechanism of resistance in this isolate?
12. The protective immunity generated by this vaccine works primarily by which of the following mechanisms?
13. Belatacept prevents T-cell activation by blocking which of the following crucial signaling pathways?
14. The hormone responsible for this patient's condition exerts which of the following metabolic effects?
15. The defective protein in this patient's platelets is most likely which of the following?
16. During a neurophysiology laboratory, students record intracellularly from a motor neuron while stimulating various afferent inputs. Stimulation of Ia afferents from the muscle spindle produces a large, fast excitatory postsynaptic potential, while stimulation of Ib afferents from the Golgi tendon organ produces a slower, smaller inhibitory postsynaptic potential. Which of the following best explains the difference in time course between these two synaptic responses?
17. Which of the following is the most appropriate conclusion?
18. The neuropathological diagnosis for this condition is confirmed by finding eosinophilic intracytoplasmic inclusions composed of alpha-synuclein within which of the following?
19. This patient's condition is due to a deficiency of a mineral that is essential for the function of which of the following proteins?
20. What is the primary purpose of administering the rabies immune globulin in this situation?

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