biol 1.1

• Using a light microscope


  View animal and plant cells
• Cell differentiation


  • Cells in multicellular organisms become adapted for specific functions
• Levels of organisation within organisms

  1. Tissues are groups of similar cells with a similar function

  2. Organs may comprise several tissues performing specific functions

  3. Organs are organised into organ systems, which work together to form organisms
• Diffusion


  Movement of substances down a concentration gradient
• Role of cell membrane in diffusion

  Allows only certain substances to pass through, most importantly oxygen and carbon dioxide
• Visking tubing


  • Model of living material
  • Used in experiments to demonstrate diffusion
• Osmosis


  Diffusion of water through a selectively permeable membrane from a region of high water (low solute) concentration to a region of low water (high solute) concentration
• Active transport


  Active process whereby substances can enter cells against a concentration gradient
• Enzymes


  Proteins made by living cells that speed up/catalyse the rate of chemical reactions
• Enzyme structure


  Composed of different amino acids linked to form a chain which is then folded into a specific shape
• Enzyme active site


  Specific shape enables it to function, "lock and key" modelling
• Temperature and pH


  Effect on enzyme activity, boiling denatures most enzymes