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USMLE Step 1-style Practice Questions
Original practice questions for the USMLE Step 1-style basic science practice (Practice in the style of the USMLE (FSMB & NBME); not affiliated), mixed across 2 topics with instant answers and explanations. Practise by topic below or take the timed mock test.
USMLE Step 1-style mixed practice
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Q1.BiologyPhotosynthesis takes place in the:
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Answer: A — Chloroplasts
Chloroplasts contain chlorophyll that captures light energy.
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Q2.ChemistryA solution with pH 3 is:
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Answer: A — Acidic
pH below 7 is acidic.
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Q3.BiologyWhich blood vessels carry blood away from the heart?
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Answer: D — Arteries
Arteries carry blood away from the heart.
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Q4.ChemistryWhat is the pH of a solution with [H⁺] = 10⁻² mol/L?
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Answer: D — 2
pH = −log[H⁺] = −log(10⁻²) = 2.
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Q5.BiologyBile is produced by the:
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Answer: D — Liver
Bile is made in the liver and stored in the gall bladder.
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Q6.ChemistryWhich gas is responsible for most of the greenhouse effect from human activity?
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Answer: C — Carbon dioxide
CO₂ from burning fossil fuels is the largest human-caused contributor.
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Q7.BiologyIn humans, the sex of a child is determined by the chromosome from the:
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Answer: C — Father
The father contributes either an X or a Y chromosome.
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Q8.Chemistry58.5 g of NaCl (molar mass 58.5) is dissolved to make 2000 mL of solution. Find the molarity.
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Answer: C — 0.5 M
Moles = 58.5/58.5 = 1; molarity = moles ÷ litres = 1 ÷ 2 = 0.5 M.
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Q9.BiologyWhich enzyme in saliva begins starch digestion?
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Answer: C — Salivary amylase (ptyalin)
Salivary amylase breaks starch into maltose.
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Q10.ChemistryWhich bond is formed by the sharing of electrons?
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Answer: D — Covalent
Covalent bonds share electron pairs.
About USMLE Step 1-style
USMLE Step 1-style basic science practice — conducted by Practice in the style of the USMLE (FSMB & NBME); not affiliated. Foundational biomedical science practice for medical students preparing for licensing exams.
Original practice questions written for this site in the style and difficulty of each exam’s syllabus. They are not past papers and the site is not affiliated with any exam body. Exam patterns, marking schemes and syllabi change — always check the latest official notification.
Practise by topic
- Biology questions — Learn structure → function links (mitochondria → ATP, nephron → filtration), the major hormones and their glands, and deficiency diseases.
- Chemistry questions — Moles = mass ÷ molar mass; molarity = moles ÷ litres.
- USMLE Step 1-style mock test — 25 timed questions.
USMLE Step 1-style practice topics
| Topic | Section | Question source |
|---|---|---|
| Biology | Science | Question bank |
| Chemistry | Science | Calculated + question bank |