Cell Biology

• Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration. 
• What affects the rate of diffusion?

  • Temperature
  • Concentration gradient
  • Surface area
  • Distance diffused across
• In gas exchange, oxygen diffuses from the alveoli into the bloodstream. Carbon dioxide diffuses from the bloodstream into the alveoli.
• Osmosis is the net movement of water molecules across a partially permeable membrane, from a region of higher water concentration, to a region of lower water concentration.
• Active transport is the movement of water molecules across a partially permeable membrane, from a region of higher concentration to a region of lower concentration. This requires energy from respiration.