BiochemStep is a USMLE Step 1 biochemistry question bank with focused practice questions in metabolism, genetics, molecular biology, laboratory techniques, nutrition, and integrated physiology.
Focused practice for the mechanism-heavy foundational science questions that often sit underneath clinical vignettes.
Practice the multi-step logic behind Step 1 vignettes: recognize the presentation, identify the pathway defect, and reason through the biochemical consequence.
BiochemStep includes focused Step 1-style questions across recurring foundational science mechanisms, with new questions added as the library expands.
Correct and incorrect answer explanations are written to help you rule out similar conditions, pathways, and mechanisms on future questions.
BiochemStep focuses on recurring foundational science concepts that appear across organ-system questions, including metabolism, genetics, molecular biology, laboratory techniques, nutrition, acid-base physiology, and homeostasis.
Built around how Step 1 tests
Each question is designed to connect the presentation to the underlying pathway, molecular defect, physiologic change, or treatment mechanism.
Coverage by Foundational Science Domain
Urea cycle disorders, phenylketonuria (PKU), maple syrup urine disease (MSUD), homocystinuria, alkaptonuria, cystinuria, tyrosinemia
Browse practice questions →Glycolysis, TCA cycle, pyruvate dehydrogenase deficiency, G6PD deficiency, fructose intolerance, galactosemia, lactic acidosis
Browse practice questions →Von Gierke disease, Pompe disease, Cori disease, McArdle disease, glucose-6-phosphatase deficiency, acid maltase deficiency
Browse practice questions →Beta-oxidation, ketogenesis, MCAD deficiency, cholesterol synthesis, HMG-CoA reductase, carnitine shuttle, familial hypercholesterolemia
Browse practice questions →Purine synthesis, pyrimidine synthesis, HGPRT deficiency, Lesch-Nyhan syndrome, orotic aciduria, adenosine deaminase deficiency, antimetabolites
Browse practice questions →Vitamin B12 deficiency, folate deficiency, megaloblastic anemia, thiamine deficiency, Wernicke encephalopathy, biotin deficiency, niacin, pellagra, vitamins A, D, E, and K
Browse practice questions →Kwashiorkor, marasmus, refeeding syndrome, zinc deficiency, protein-energy malnutrition, nutritional deficiencies
Browse practice questions →DNA replication, DNA repair, nucleotide excision repair, mismatch repair, xeroderma pigmentosum, transcription, translation, protein trafficking, oncometabolites
Browse practice questions →PCR, RT-PCR, qPCR, Sanger sequencing, next-generation sequencing, Southern blot, Northern blot, Western blot, ELISA, FISH, microarray analysis
Browse practice questions →Autosomal dominant, autosomal recessive, X-linked inheritance, genomic imprinting, Prader-Willi syndrome, Angelman syndrome, trinucleotide repeats, Huntington disease, Down syndrome, lysosomal storage diseases
Browse practice questions →Acid-base disorders, metabolic acidosis, metabolic alkalosis, anion gap, renal tubular acidosis, fed and fasted state, starvation, gluconeogenesis
Browse practice questions →Michaelis-Menten kinetics, Km, Vmax, competitive inhibition, noncompetitive inhibition, uncompetitive inhibition, Lineweaver-Burk plot, allosteric regulation
Browse practice questions →Complement pathway, C1 esterase inhibitor deficiency, hereditary angioedema, paroxysmal nocturnal hemoglobinuria (PNH), terminal complement deficiency
Browse practice questions →