AP Biology · Unit 2
Cell Structure and Function
Explore how cellular structures, membranes, transport, and compartmentalization allow cells to exchange matter and maintain distinct internal conditions.
Learning sequence
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Topic 2.1
Cell Structures at Work
Connect organelle structure, location, and abundance to cellular function.
Topic 2.2
Size Sets Limits
Calculate surface area-to-volume ratio and predict exchange efficiency.
Topic 2.3
The Fluid Mosaic
Build a membrane and orient its lipids, proteins, and carbohydrates.
Topic 2.4
Who Crosses?
Predict permeability from molecular size, charge, and polarity.
Topics 2.5–2.6
Moving Across Membranes
Compare passive, active, protein-mediated, and bulk transport.
Topic 2.7
Water Balance
Model tonicity, water potential, and osmoregulation.
Topics 2.8–2.10
Gradients & Compartments
Connect ATP-powered pumps, internal membranes, and endosymbiosis.
Topics 2.1–2.10
Unit 2 Assessment
Apply cell structure and transport concepts to models, calculations, and data.