organisation

• What is the function of specialised cells?

  They carry out a particular function
• What is the process called when cells become specialised?

  Differentiation
• When does differentiation occur in multicellular organisms?

  During the development of the organism
• How are specialised cells organised in multicellular organisms?

  • Specialised cells form tissues
  • Tissues form organs
  • Organs form organ systems
• What is a tissue?

  A group of similar cells
• What is an example of muscular tissue?

  Muscular tissue contracts to move
• What does glandular tissue do?

  Makes and secretes chemicals
• What is the function of epithelial tissue?

  It covers parts of the body
• What is an organ?

  A group of different tissues
• What tissues make up the stomach?

  Muscular, glandular, and epithelial tissues
• What is an organ system?

  A group of organs working together
• What is the function of the digestive system?

  Breaks down and absorbs food
• Name an organ in the digestive system.

  Stomach
• What do glands in the digestive system do?

  Produce digestive juices
• What does the liver produce?

  Bile
• What is the role of the small intestine?

  Absorbs soluble food molecules
• What is the function of the large intestine?

  Absorbs water from undigested food
• What are enzymes?

  Catalysts produced by living things
• Why are enzymes important for chemical reactions?

  They speed up reactions without being used
• What are enzymes made of?

  Chains of amino acids
• What is the active site of an enzyme?

  It fits onto the substance in a reaction
• What happens if the substrate doesn't fit the active site?

  The reaction won't be catalysed
• What is the 'lock and key' model of enzyme action?

  It describes how enzymes fit substrates
• What is the 'induced fit' model of enzyme action?

  The active site changes shape for a tighter fit
• How does temperature affect enzyme activity?

  Higher temperatures increase reaction rates initially
• What happens to enzymes at high temperatures?

  They can become denatured
• What is optimum temperature for enzymes?

  The temperature at which they work best
• How does pH affect enzyme activity?

  Extreme pH can denature enzymes
• What is the optimum pH for most enzymes?

  Often neutral pH 7
• What is the optimum pH for pepsin?

  pH 2
• What is the procedure to investigate the effect of pH on enzyme activity using amylase?

  1. Prepare iodine solution in wells.
  2. Heat water to 30-35 °C.
  3. Add amylase solution to boiling tube.
  4. Add starch solution and start timing.
  5. Sample every 30 seconds with iodine.
  6. Repeat with different pH buffers.
  7. Control variables for fairness.
• How do you calculate the rate of reaction?

  Rate = change ÷ time
• What do digestive enzymes do?

  • Break down big molecules
  • Convert them into smaller molecules
  • Allow absorption into the bloodstream
• What do carbohydrates break down into?

  Simple sugars
• What do proteins break down into?

  Amino acids
• What do fats break down into?

  Fatty acids
• What is the formula to calculate the rate of reaction?

  Rate = change ÷ time
• How can the catalase experiment be adapted?

  • Investigate factors affecting amylase activity
  • Use a water bath at different temperatures
• What are the main digestive enzymes and their functions?

  • Amylase: Breaks down starch into sugars
  • Protease: Breaks down proteins into amino acids
  • Lipase: Breaks down lipids into glycerol and fatty acids
• Where are digestive enzymes produced?

  By cells in glands and gut lining