Everything you need to plan USMLE Step 1 revision: the exam format, a system-by-system syllabus breakdown, sample vignette questions with mechanism-based explanations, and a bank of 9,000+ SBAs plus 300 tutorials mapped to the foundational sciences.
What the exam covers
Basic science concepts as applied to the practice of medicine, with an emphasis on principles and mechanisms.
Integrated clinical vignettes that combine physiology, pathology, pharmacology and biochemistry.
Foundational science underpinning safe and effective patient care.
Exam format
A single computer-based exam, delivered as up to 7 hours of testing time including breaks.
Up to 280 multiple-choice questions across multiple blocks of up to 40 questions.
Reported as pass/fail only.
How Examrix helps you pass USMLE Step 1
A USMLE Step 1 question bank of 9,000+ vignette-style single-best-answer questions across the basic sciences.
300 syllabus tutorials with mechanism-based explanations that connect physiology, pathology and pharmacology.
Timed exam mode with 20- and 40-question blocks that mirror real test-day pacing.
Per-system analytics and anonymised peer comparison to prioritise weak areas before test day.
Topic coverage
BiochemistryPhysiologyPharmacologyPathologyMicrobiology & immunologyBehavioural scienceAnatomy & embryologyCardiovascular systemRenal systemGastrointestinal systemNervous system & special senses
USMLE Step 1 syllabus breakdown
Foundational sciences
Biochemistry, metabolism and molecular genetics
Cell biology, histology and general pathology
Immunology, hypersensitivity and immunodeficiency
Microbiology: bacteriology, virology, mycology and parasitology
General principles of pharmacology and toxicology
Cardiovascular, respiratory and renal systems
Cardiac cycle, haemodynamics and ECG interpretation
Atherosclerosis, ischaemic heart disease and heart failure
Pulmonary mechanics, gas exchange and V/Q relationships
Obstructive and restrictive lung disease
Renal physiology, acid–base balance and glomerular disease
Gastrointestinal, endocrine and reproductive systems
GI secretion, motility and hepatobiliary disease
Diabetes, thyroid, adrenal and pituitary pathophysiology
Calcium homeostasis and bone metabolism
Reproductive endocrinology and embryology
Neuroscience, musculoskeletal and haematology
Neuroanatomy, tracts and lesion localisation
Neuropharmacology and neurodegenerative disease
Muscle physiology, connective tissue and skin pathology
Anaemias, haemostasis and haematological malignancy
Behavioural science, biostatistics and ethics
Psychiatric disorders and psychopharmacology
Study design, bias and confounding
Sensitivity, specificity and predictive values
Medical ethics, communication and patient safety
Sample USMLE Step 1 questions
Three example single-best-answer questions in the style of the USMLE Step 1 bank, with the reasoning behind the correct answer.
Question 1
A 24-year-old man is brought to the emergency department after a fall. He is tall with long fingers, a high-arched palate and upward lens dislocation. Echocardiography shows aortic root dilatation. A defect in which protein is most likely responsible?
A.Type I collagen
B.Fibrillin-1
C.Type III collagen
D.Elastin
E.Dystrophin
Answer: Fibrillin-1
Marfan syndrome results from FBN1 mutations affecting fibrillin-1, a glycoprotein scaffold for elastic fibres. Loss of fibrillin also releases excess TGF-β, driving aortic root dilatation and superotemporal lens dislocation. Type I collagen defects cause osteogenesis imperfecta, type III collagen the vascular form of Ehlers–Danlos, and elastin haploinsufficiency Williams syndrome.
Question 2
A 62-year-old woman with type 2 diabetes is started on a new oral agent. Two months later her HbA1c has fallen and she has lost 3 kg, but she reports recurrent vulvovaginal candidiasis. Which mechanism best explains these findings?
A.Inhibition of sodium–glucose cotransporter 2 in the proximal tubule
B.Stimulation of pancreatic beta-cell sulfonylurea receptors
C.Inhibition of hepatic gluconeogenesis via AMPK activation
D.Inhibition of dipeptidyl peptidase-4
E.Activation of PPAR-γ in adipose tissue
Answer: Inhibition of sodium–glucose cotransporter 2 in the proximal tubule
SGLT2 inhibitors block proximal tubular glucose reabsorption, producing glycosuria with modest weight loss and a well-recognised risk of genital mycotic infection. Sulfonylureas cause weight gain and hypoglycaemia, metformin is weight-neutral to weight-reducing but does not cause glycosuria, and thiazolidinediones cause fluid retention and weight gain.
Question 3
A 30-year-old woman has episodic weakness of the eyelids and extraocular muscles that worsens through the day. Repetitive nerve stimulation shows a decremental response. Which is the most likely site of pathology?
A.Presynaptic voltage-gated calcium channels
B.Postsynaptic acetylcholine receptors
C.Anterior horn cells
D.Peripheral myelin sheath
E.Muscle sarcomere proteins
Answer: Postsynaptic acetylcholine receptors
Myasthenia gravis is caused by autoantibodies against the postsynaptic nicotinic acetylcholine receptor, reducing endplate potentials and producing fatigable weakness with a decremental response on repetitive stimulation. Lambert–Eaton targets presynaptic calcium channels and shows an incremental response after exercise.
