Organisation

• What organs make up the digestive system?

  Mouth, oesophagus, stomach, liver, pancreas, intestines
• Where is food absorbed in the digestive system?

  In the small intestine
• What are enzymes?

  Proteins that speed up reactions
• What is the function of an enzyme's active site?

  It fits a specific substrate for reaction
• What is a common enzyme that breaks down proteins?

  Protease
• What does lipase break down?

  Fats into fatty acids and glycerol
• Where are enzymes primarily made?

  Pancreas and small intestine
• Why does protease work best in the stomach?

  Because it thrives in acidic conditions
• What is the role of bile in digestion?

  Emulsifies fats for easier breakdown
• How does visking tubing demonstrate nutrient absorption?

  It shows how broken down food enters blood
• What happens to an enzyme if the pH changes?

  It can denature and lose function
• What does 'optimum pH' mean for enzymes?

  It is the pH where enzymes work best
• How does temperature affect enzyme activity?

  Increases reaction rate until denaturation
• What happens when substrate concentration increases?

  Reaction rate increases until active sites are full
• What are the key variables in enzyme experiments?

  • Independent variable: what you change
  • Dependent variable: what you measure
  • Control variable: what you keep the same
• Why might industries choose lower temperatures for enzyme reactions?

  To save energy and reduce costs
• How should substances be prepared before mixing in a water bath?

  They should be preheated for 5 minutes
• How can results be made more repeatable in experiments?

  By repeating results and testing smaller intervals
• What is accuracy in scientific measurements?

  How close values are to the true value
• How is the rate of reaction calculated for enzymes?

  By finding the gradient of the line of best fit
• What are the tests for different food substances?

  • Starch: Iodine solution (blue/black)
  • Sugar: Benedict's reagent (red/orange)
  • Fat: Ethanol and water (cloudy white)
  • Protein: Biuret test (purple)
• What is respiration?

  A reaction that releases energy in cells
• Where does respiration occur in cells?

  In the mitochondria
• What is the equation for aerobic respiration?

  Glucose C6H12O6 + Oxygen 6O2→ Carbon Dioxide 6CO2 + Water 6H2O + Energy
• Why do muscle cells have many mitochondria?

  To release lots of energy during respiration
• What does metabolism include?

  • Conversion of starch to glucose
  • Converting lipids into glycerol and fatty acids
  • Making amino acids from glucose and nitrate
  • Respiration
  • Breakdown of excess proteins to urea
• How does exercise affect respiration?

  Increases breathing and heart rate for more oxygen
• What happens if more energy is taken in than used?

  Body mass increases
• What is anaerobic respiration?

  Respiration without oxygen
• What is produced during anaerobic respiration in humans?

  Lactic acid and energy
• What happens after strenuous exercise regarding lactic acid?

  Heart and breathing rates slowly decrease
• How is lactic acid removed from cells?

  Converted back to glucose in the liver
• What is fermentation in yeast cells?

  Anaerobic respiration producing ethanol and carbon dioxide
• What is diffusion?

  • Spreading out of particles
  • Net movement from high to low concentration
• How can the rate of diffusion be increased?

  By increasing temperature and surface area
• What is the formula for calculating surface area to volume ratio?

  Surface area ÷ volume
• Why do smaller organisms rely on diffusion?

  They have a larger surface area to volume ratio
• What adaptations do lungs have for gas exchange?

  Large surface area and thin membranes
• What is the role of alveoli in the lungs?

  Facilitate gas exchange with blood
• What is asthma?

  An allergy causing difficulty in breathing