Free AP Biology practice questions
AP Biology rewards reasoning over rote recall — but you still have to know the core facts cold before you can analyze data and design experiments. Try the AP-style samples below, see each one fully explained (including why every wrong choice is wrong), then keep practicing by unit. No credit card.
What the AP Biology exam looks like
So you know what these samples are preparing you for. AP Biology is a college-level introductory biology course built on eight units, from the chemistry of life through cells, energetics, heredity, gene expression, natural selection and ecology.
Format and scoring can change year to year — always confirm current details on College Board — AP Biology. The questions below are AP-style practice questions, not real or official AP exam questions.
AP-style practice questions
Three to warm up on. Pick an answer, submit, and read the full explanation — the correct choice, why the main traps fail, and the skill it tests.
Explanation — Correct: B
Most ATP from cellular respiration is generated by oxidative phosphorylation, which takes place along the inner mitochondrial membrane (the electron transport chain and ATP synthase). That makes the mitochondrion the cell's main ATP producer.
Why A is wrong: the ribosome is the site of protein synthesis (translation), not ATP production. It builds polypeptides — it doesn't run respiration.
Why C is wrong: the nucleus stores and protects the DNA and is where transcription happens. It directs the cell but is not where respiration generates ATP.
Skill: match each organelle to its primary function. "Powerhouse" = mitochondrion; protein synthesis = ribosome; DNA storage = nucleus; packaging/shipping = Golgi.
Explanation — Correct: B
Natural selection is differential reproductive success of heritable variation: individuals whose inherited traits fit the current environment leave more offspring, so those traits become more common over generations. That's exactly what B says.
Why A is wrong: that's Lamarckism — the discredited idea that traits acquired during a lifetime (like a stretched neck) are inherited. Selection acts on variation that is already heritable, not on changes an individual makes.
Why C is wrong: mutations are random with respect to need. They happen whether or not they're useful; the environment then filters which ones persist. Organisms don't summon helpful mutations on demand.
Skill: define selection as differential survival and reproduction of heritable variation — and reject "for the good of the species" and "need-driven mutation" phrasings.
Explanation — Correct: C
In DNA, base pairing is complementary and specific: adenine pairs with thymine (two hydrogen bonds) and guanine pairs with cytosine (three hydrogen bonds). So adenine's partner is thymine.
Why A and B are wrong: guanine and cytosine are each other's partner, not adenine's. Adenine is a purine and pairs with a pyrimidine — but specifically thymine, not cytosine.
Why D is wrong: uracil replaces thymine in RNA, where adenine does pair with uracil. The question asks about DNA, where the complement is thymine.
Skill: memorize the pairs — A–T and G–C in DNA — and remember that uracil is the RNA-only substitute for thymine.
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Full sets, every unit, a full explanation on every question. Daily free to start — no credit card.
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A full explanation on every answer
Not just an answer key — a four-part breakdown of why the right answer is right, why each wrong choice fails, the skill it tests, and the trap to avoid. You learn the reasoning, not just the letter.
Built to match the AP exam
Written to the format and difficulty of AP Biology and aligned to the College Board's course framework, with data-analysis and experimental-design style items across all eight units.
Practice unit by unit
Work one unit at a time, then mix units the way the exam does, and let the mistake bank resurface what you miss so weak spots actually close.
Practice it, unit by unit.
Reading about biology isn't the same as answering AP-style questions and learning from every miss. Start free and practice by unit.
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