Priority 1: Definitions

Learn the exact definitions: every word matters:

  • Diffusion: net movement of particles from a region of higher concentration to a region of lower concentration
  • Osmosis: net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution) through a partially permeable membrane
  • Active transport: movement of ions or molecules from a region of lower concentration to higher concentration (against the concentration gradient), requiring energy from respiration

Priority 2: Osmosis experiments

Predict what happens to plant cells and animal cells in different solutions. In a dilute solution: plant cells become turgid (vacuole swells, pushes against cell wall); animal cells swell and may burst (lysis). In a concentrated solution: plant cells plasmolyse (vacuole shrinks, membrane pulls away from wall); animal cells crenate (shrink and wrinkle).

Priority 3: Comparing all three

Know how to compare diffusion, osmosis, and active transport in a table: what moves, direction, energy requirement, membrane needed, examples.