1. True or False: Lactase is effective at breaking down lactose into glucose and galactose at temperatures above 50°C. - Answer: False. Rationale: Lactase, like most enzymes, has an optimal temperature range in which it operates effectively, usually around 37°C. Temperatures above 50°C can denature the enzyme, reducing its activity. 2. Fill in the blank: The enzyme lactase has an optimal pH at which it exhibits peak activity, which is generally around pH ______. - Answer: 6. Rationale: Lactase's optimal pH is slightly acidic, reflecting the conditions in the small intestine where it is most active. 3. Multiple Choice: Which of the following is not a product of lactase activity? A) Glucose B) Galactose C) Fructose D) All of the above are products. - Answer: C) Fructose. Rationale: Lactase specifically catalyzes the hydrolysis of lactose into glucose and galactose. 4. Open-ended: Describe the mechanism by which lactase interacts with its substrate. - Answer: Lactase follows the lock-and-key model where the lactose molecule fits into the active site of the lactase enzyme. This binding induces a conformational change in the enzyme, leading to the cleavage of lactose into glucose and galactose. 5. True or False: Lactase's activity is unaffected by the presence of competitive inhibitors.