APentixFree · No install · 7,106+ questions
Practice like it's exam day.
Real AP pacing, real rubrics, plain-language explanations. Focus mode keeps you on the question; the score predictor keeps you honest.
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AP Biology
Which organelle is the primary site of ATP synthesis in eukaryotic cells?
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AP Biology: 743 questions
Molecular genetics, evolution, and ecology: 8 units with lab-style data questions.
Unit guides + cheatsheets includedOpen AP Biology hub →Built like the exam
Everything maps to how the AP test actually scores you.
Real AP-style questions
Stimulus sets, FRQs, and MCQs matched to College Board unit weighting, difficulty-tagged.
Score predictor
Official curves for 20+ exams turn raw practice into a projected 1–5.
Progress rings
Questions answered and mastery per subject, visible at a glance on your profile.
Export to any AI
Missed questions export as a text file you can drop into your favorite chatbot for deeper help.
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18 courses, from AP Biology to AP Music Theory.
Questions, answered
›Is APentix free?
Yes. Every practice question, unit guide, cheatsheet, flashcard deck, and the score predictor are free. A free account syncs your progress across devices and unlocks classes, friends, and study streaks.
›Are the questions like real AP exam questions?
Questions follow College Board unit weighting and formats: stimulus-based MCQs, standalone MCQs, and free-response questions with rubrics. Fact-dense subjects are fact-checked during authoring, and every question ships with a concise explanation.
›Do I need an account to practice?
No. You can try the demo quiz on this page and browse every subject hub without signing up. Accounts add saved progress, mastery rings, assignments, and classroom games.
›Can teachers use APentix in class?
Yes. Teachers create a class, share a 6-digit join code, assign practice sets with due dates, and can host live classroom games that students join with a PIN from any device.
›How does the score predictor work?
It uses released AP scoring curves for 20+ exams: enter your raw MCQ and FRQ counts and it maps them to a projected 1–5, so you always know where you stand.
›How are my essays graded?
Free-response and essay work is graded by AI against the official College Board rubric — strictly, like a real AP reader. Grading is routed across frontier models (DeepSeek V4 Flash, Gemini 3.7 Flash, GPT 5.6 Luna, or Muse Spark 1.2), so feedback stays fast even at peak times. You can always cross-check with the built-in rubric self-scorer.