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AP Biology Unit 2  ·  Sprint Review  ·  Free

AP Biology Unit 2 — The Cell

One-page sprint review

Ten pages on cell structure, surface-area-to-volume calculations, membrane transport, tonicity, and endosymbiosis — the most calculation-heavy unit on the course.

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Exam Weight
10–13%
MCQs
6–8
FRQ Appearance
Very Frequent
Sprint Time
~2 hours

Quick Glance — all topics in this unit

Priority, exam format, and the trap that most often costs the point. Transcribed from page 1 so this content is searchable.

TopicPriorityFormatKey trap / must-know
2.1 Cell Structure★★★MCQ, FRQProkaryotes DO have ribosomes (70S); nucleus is INSIDE the nucleus.
2.2 Cell Size & SA:V★★★MCQ, CalcLarger cell = LOWER SA:V = LESS efficient (not more).
2.3 Plasma Membrane★★★MCQ, FRQCholesterol is a BUFFER — increases fluidity in cold, decreases it in heat.
2.4 Permeability★★MCQWater crosses slowly via aquaporins; ions CANNOT cross without channels.
2.5–2.6 Passive Transport★★★MCQ, FRQFacilitated diffusion uses proteins but needs NO ATP — still passive.
2.7 Tonicity / Osmosis★★★MCQ, Calc, DataPlant cells: hypo → turgid (NOT lysis); animal cells: hypo → lysis.
2.8 Active Transport★★★MCQ, FRQNa+/K+ pump: 3 Na+ OUT, 2 K+ IN — net charge moves out → electrochemical gradient.
2.9–2.10 Compartments + Endosymbiosis★★★MCQ, FRQCite 3+ pieces of evidence for endosymbiosis; mitochondria in ALL eukaryotes.

Topic-by-topic visual review

Nine pages, one topic each. Open the PDF for print quality, or scroll to study on screen.

Cover: Unit 2 overview — calculation-heavy unit. Osmosis, water potential, SA:V appear on almost every exam.
Cover  ·  Unit 2 overview — calculation-heavy unit. Osmosis, water potential, SA:V appear on almost every exam.
2.1 Cell Structure: Organelles in prokaryotes vs eukaryotes, comparing organelle inventories and the nuclear membrane distinction.
2.1 Cell Structure  ·  Organelles in prokaryotes vs eukaryotes, comparing organelle inventories and the nuclear membrane distinction.
2.2 Cell Size & SA:V: Surface-area-to-volume calculations and why bigger cells lose efficiency.
2.2 Cell Size & SA:V  ·  Surface-area-to-volume calculations and why bigger cells lose efficiency.
2.3 Plasma Membrane: Fluid mosaic model, phospholipid bilayer, cholesterol as fluidity buffer.
2.3 Plasma Membrane  ·  Fluid mosaic model, phospholipid bilayer, cholesterol as fluidity buffer.
2.4 Permeability + Channels: What crosses freely, what needs aquaporins, what needs gated channels.
2.4 Permeability + Channels  ·  What crosses freely, what needs aquaporins, what needs gated channels.
2.5–2.6 Passive Transport: Simple diffusion, facilitated diffusion, channel proteins, no-ATP rules.
2.5–2.6 Passive Transport  ·  Simple diffusion, facilitated diffusion, channel proteins, no-ATP rules.
2.7 Tonicity & Osmosis: Hypotonic / hypertonic / isotonic with the plant-vs-animal cell behavior grid.
2.7 Tonicity & Osmosis  ·  Hypotonic / hypertonic / isotonic with the plant-vs-animal cell behavior grid.
2.8 Active Transport: Na+/K+ pump stoichiometry, primary vs secondary active transport, electrochemical gradient.
2.8 Active Transport  ·  Na+/K+ pump stoichiometry, primary vs secondary active transport, electrochemical gradient.
2.9–2.10 Compartments + Endosymbiosis: Internal organization and the evidence chain for endosymbiotic origin of mitochondria and chloroplasts.
2.9–2.10 Compartments + Endosymbiosis  ·  Internal organization and the evidence chain for endosymbiotic origin of mitochondria and chloroplasts.
Final Review — Traps + Checklist: Highest-frequency Unit 2 traps and the pre-exam checklist on transport calculations.
Final Review — Traps + Checklist  ·  Highest-frequency Unit 2 traps and the pre-exam checklist on transport calculations.

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