Transport in cells

• Diffusion


  Net movement of particles from high to low concentration.
• Factors affecting diffusion


  Concentration gradient, temperature, surface area.
• Examples of diffusion


  Lungs: oxygen in, carbon dioxide out. Kidney: urea out.
• Adaptations for diffusion


  Single-celled organisms have high surface area to volume ratio.
• Surface area to volume ratio calculation

  Surface Area = Number of Sides x (Side Length x Side Width); Volume = Length x Width x Depth; Ratio = Surface Area:Volume.
• Factors for gas exchange surface


  Large area, thin membrane, good blood supply, ventilation.
• Osmosis


  Water movement from dilute to concentrated solution through a membrane.
• Isotonic solution to a cell

  Equal concentrations inside and outside the cell.
• Hypertonic solution to a cell

  Higher concentration outside the cell than inside.
• Hypotonic solution to a cell


  Lower concentration outside the cell than inside.
• Animal cell in hypotonic solution


  Cell bursts from water influx.
• Animal cell in hypertonic solution


  Cell shrivels from water loss.
• Plant rigidity mechanism


  Turgor pressure from water influx by osmosis.
• Plant cell in hypertonic solution


  Cell loses water, vacuole shrinks, potential plasmolysis.
• Active transport


  Molecules move from dilute to concentrated area against gradient, using energy.
• Plant root hair cells' active transport


  Absorb mineral ions from soil for growth.
• Active transport in digestion absorption


  Moves glucose from gut to blood against gradient for tissue use.