Question 1: Define an enzyme and explain its role in the digestive system.

Answer: An enzyme is a biological catalyst that speeds up chemical reactions; in digestion, it breaks down large food molecules into smaller, absorbable units.

Question 2: Describe the mechanism by which enzymes catalyse reactions in the digestive system.

Answer: Enzymes work by lowering the activation energy of reactions, binding to specific substrate molecules at their active sites, facilitating their breakdown or formation.

Question 3: Identify the enzyme responsible for breaking down starch in the mouth and small intestine.

Answer: Amylase

Question 4: What is the optimal pH range for the enzyme pepsin in the stomach?

Answer: pH 1.5 to 2

Question 1: If an enzyme catalyses the breakdown of 50 mg of substrate in 10 minutes, what is the reaction rate in mg per minute?

Answer: Reaction rate = 50 mg / 10 min = 5 mg/min

Question 2: A certain enzyme has an activity of 200 units per millilitre. If 2 ml of this enzyme solution is used in a reaction, how many total enzyme units are present?

Answer: Total units = 200 units/ml × 2 ml = 400 units

Question 1: Design a simple experiment to test the effect of temperature on amylase activity. Include the variables involved and safety precautions.

Answer: The experiment involves mixing a fixed amount of starch solution with amylase at different temperatures (e.g., 20°C, 37°C, 50°C). The independent variable is temperature; the dependent variable is the rate of starch breakdown, measured by iodine test. Control variables include enzyme and substrate amounts. Safety precautions include handling hot liquids carefully and wearing safety goggles.

Question 2: Identify two variables that must be controlled during the experiment and explain why.

Answer: The amount of enzyme and substrate must be controlled to ensure that any differences in activity are due to temperature changes, not concentration differences.

Question 1: A student measures the rate of starch breakdown by amylase at various pH levels. The data shows maximum activity at pH 7, with reduced activity at pH 5 and pH 9. Explain why pH affects enzyme activity.

Answer: pH affects enzyme activity because it influences the shape of the enzyme's active site and overall protein structure. Deviations from the optimal pH can lead to denaturation or reduced binding efficiency, thus decreasing activity.

Question 1: Describe the importance of enzymes in the digestion of proteins, including the specific enzyme involved and its optimal conditions.

Answer: Enzymes are crucial for digesting proteins because they speed up the breakdown into amino acids, which can be absorbed. The enzyme involved is protease, such as pepsin in the stomach, which works best at pH around 2, functioning effectively in the acidic environment.

Question 2: Explain how enzyme inhibitors could affect digestion, providing an example relevant to human health or industry.

Answer: Enzyme inhibitors can reduce or block enzyme activity, affecting digestion. For example, certain drugs inhibit amylase to manage blood sugar levels in diabetics. In industry, inhibitors are used to control enzyme activity during food processing.

Question 1: Discuss how enzymes are used in the food industry to improve product quality or shelf-life. Provide specific examples.

Answer: Enzymes like amylase and protease are used to modify food textures, improve clarity of fruit juices, and tenderise meat. They also help in reducing sugar content, thus extending shelf-life and improving product quality.

Question 2: Describe a technological advancement involving enzymes that could benefit human health or environmental sustainability.

Answer: Genetically engineered enzymes that catalyse environmentally friendly processes, such as biodegradable detergents or biofuel production, help reduce pollution and reliance on non-renewable resources, benefiting both health and sustainability.