Question 1: Define the Lock and Key Theory as it applies to enzymes in the digestive system.

Answer: The Lock and Key Theory states that enzymes have a specific active site that fits only particular substrate molecules, similar to a key fitting only a specific lock.

Question 2: Explain why enzymes are considered specific to their substrates in the Lock and Key Model.

Answer: Enzymes are specific because their active sites have a unique shape that only fits specific substrate molecules, ensuring precise biochemical reactions.

Question 3: Describe what happens to an enzyme and substrate during the reaction according to the Lock and Key Theory.

Answer: The substrate binds to the enzyme’s active site, forming an enzyme-substrate complex, then the substrate is broken down or transformed, and the enzyme remains unchanged.

Question 1: An enzyme catalyses the breakdown of 50 mg of substrate in 10 minutes. Calculate the enzyme activity in mg/min.

Answer: Enzyme activity = 50 mg / 10 min = 5 mg/min

Question 2: If the optimal temperature for an enzyme is 37°C, and activity drops to 20% at 50°C, what is the enzyme activity at 50°C if the activity at 37°C is 100 units?

Answer: Activity at 50°C = 100 units × 20% = 20 units

Question 1: Describe a simple experiment to test how temperature affects enzyme activity, including the variables involved and safety precautions.

Answer: An experiment can be set up by incubating enzyme and substrate mixtures at different temperatures (e.g., 20°C, 37°C, 50°C). The independent variable is temperature, the dependent variable is enzyme activity (measured by product formation), and the control is the reaction at optimal temperature. Safety precautions include wearing gloves and eye protection when handling hot equipment or chemicals, and ensuring proper waste disposal.

Question 1: A series of experiments measured enzyme activity at pH values of 5, 7, and 9. The activities recorded were 30, 100, and 40 units respectively. Interpret the data to identify the optimal pH for enzyme activity and explain why activity decreases at pH 5 and 9.

Answer: The optimal pH for enzyme activity is 7, where the activity is highest at 100 units. The decrease in activity at pH 5 and 9 suggests that the enzyme's active site shape is affected by pH changes, which can alter its ability to bind substrate, reducing efficiency.

Question 1: Explain the significance of enzyme specificity in the digestive system and how the Lock and Key Theory accounts for this specificity. (6 marks)

Answer: Enzyme specificity ensures that enzymes only catalyse specific reactions, preventing unwanted side reactions. The Lock and Key Theory explains this by showing that the enzyme’s active site has a specific shape that only fits a particular substrate. This precise fit guarantees that each enzyme only acts on its specific substrate, maintaining efficiency and regulation within the digestive system.

Question 1: Describe how understanding enzyme specificity and the Lock and Key Theory can improve the production of biofuels.

Answer: Understanding enzyme specificity allows scientists to select or engineer enzymes that efficiently break down specific biomass components, like cellulose, into biofuels. The Lock and Key Theory helps in designing enzymes tailored to target specific substrates, improving yield and reducing costs in biofuel production.