Question 1: Define the Lock and Key Theory in the context of enzyme action within the digestive system.

Answer: The Lock and Key Theory describes how enzymes (keys) are specific to substrates (locks), fitting together precisely to catalyse reactions.

Question 2: Explain why enzymes are specific to their substrates according to Lock and Key Theory.

Answer: Because the active site of an enzyme has a specific shape that only fits a particular substrate, similar to a key fitting a specific lock.

Question 3: Calculate the rate of enzyme activity if 150 substrate molecules are broken down in 30 seconds. Express your answer in molecules per second.

Answer: 5 molecules per second

Question 4: A student adds 2.0 mL of substrate solution with a concentration of 50 mol/L to an enzyme solution. After 60 seconds, 25 mol of substrate are broken down. What is the initial substrate concentration in mol/L?

Answer: 12.5 mol/L

Question 5: Identify the independent and dependent variables in an experiment testing the effect of temperature on enzyme activity.

Answer: Independent variable: Temperature; Dependent variable: Rate of enzyme activity

Question 6: Describe two safety precautions that should be followed during enzyme experiments in the laboratory.

Answer: Wearing lab coats and gloves to prevent enzyme or chemical contact; Ensuring proper disposal of biological materials.

Question 7: A substrate concentration is increased from 10 mol/L to 50 mol/L while keeping enzyme concentration constant. Describe the expected effect on the rate of enzyme activity.

Answer: The rate of enzyme activity is expected to increase initially and then plateau as the enzyme becomes saturated with substrate.

Question 8: Interpret the following scenario: When enzyme concentration remains constant, increasing substrate concentration results in a faster breakdown of substrate up to a point. What is this point called?

Answer: The point of saturation, where all active sites are occupied, and increasing substrate concentration no longer increases the rate.

Question 9: Explain how the Lock and Key model can be used to develop enzyme inhibitors for industrial or medical purposes.

Answer: By designing molecules that fit into the active site like a key that blocks the lock, preventing substrate binding and enzyme activity. These inhibitors can be used to control reactions in industry or treat diseases by inhibiting specific enzymes.

Question 10: In a hypothetical scenario, an enzyme's active site is altered and no longer fits its substrate. Explain what effect this change has on enzyme activity and the Lock and Key Theory.

Answer: The enzyme's activity would decrease or stop because the active site no longer matches the substrate, invalidating the Lock and Key model. This highlights the importance of the specific shape of active sites for enzyme function.