Enzymes

• What are enzymes essential for in chemical reactions?

  They make chemical reactions occur.
• What do enzymes help with in metabolism?

  They help reactions happen quickly.
• What is a catalyst?

  A substance that speeds up a reaction.
• How many different enzymes are there for biological reactions?

  Every reaction has its own enzyme.
• What is a substrate?

  A molecule changed in a reaction.
• What is the active site of an enzyme?

  The part where it joins the substrate.
• Why are enzymes substrate specific?

  They usually only work with one substrate.
• What happens if a substrate's shape doesn't match the active site?

  The reaction can't be catalysed.
• What is the 'lock and key' hypothesis?

  The substrate fits into the enzyme like a key.
• How does temperature affect enzyme activity?

  Higher temperature increases reaction rate initially.
• What happens to enzymes at very high temperatures?

  Bonds holding the enzyme break, changing shape.
• What does it mean when an enzyme is denatured?

  The active site shape changes and stops working.
• What is the optimum temperature for most human enzymes?

  About 37°C.
• How does pH affect enzyme activity?

  Extreme pH changes denature the enzyme.
• What is the optimum pH for most enzymes?

  Often neutral pH 7, but not always.
• What is the optimum pH for pepsin?

  pH 2.
• How does substrate concentration affect enzyme activity?

  Higher concentration increases reaction rate.
• What happens when all active sites are full?

  Adding more substrate makes no difference.
• What can you investigate regarding enzyme activity?

  You can investigate the effect of variables.
• What can you measure in an enzyme activity experiment?

  The amount of hydrogen peroxide broken down.
• How can you measure oxygen production in an experiment?

  Use a multi-meter to measure oxygen produced.
• What should you control in an enzyme activity experiment?

  Variables like pH and substrate size.
• How do you calculate the mean rate of reaction?

  Divide mean volume of oxygen by time.
• What does amylase do in starch breakdown?

  It helps break down starch into simpler sugars.
• How can you detect starch in a solution?

  Using iodine solution that changes color.
• What is the rate of reaction if 36 cm³ of product is released in 2 minutes at 4°C?

  $18 \text{ cm}^3/\text{s}$
• What are the factors affecting enzyme activity?

  • Temperature
  • pH
  • Substrate concentration
  • Enzyme concentration
• What are the steps to investigate enzyme activity?

  1. Set up the experimental apparatus.
  2. Control variables (e.g., pH, temperature).
  3. Measure the rate of reaction.
  4. Record and analyze data.
• What are the effects of temperature on enzyme activity?

  • Increased temperature speeds up reactions initially.
  • High temperatures can denature enzymes.
  • Each enzyme has an optimum temperature.
• What are the effects of pH on enzyme activity?

  • Extreme pH can denature enzymes.
  • Each enzyme has an optimum pH.
  • Example: Pepsin works best at pH 2.
• What are the effects of substrate and enzyme concentration on reaction rates?

  • Higher substrate concentration increases reaction rate until saturation.
  • Higher enzyme concentration increases reaction rate until substrate is limited.