Quiz Chapter 5: Metabolism and Enzymes

1. What effect do heavy metal ions like mercury (Hg2+) or lead (Pb2+) have on enzyme activity?

1. A. They act as cofactors to accelerate reaction rates.
2. B. They act as enzyme inhibitors that disrupt structure and stop catalysis.
3. C. They convert non-reducing sugars into reducing sugars.
4. D. They shift the optimum pH to acidic ranges.

2. Which enzyme is added to biological washing powders to effectively remove blood and egg stains from clothing?

1. A. Cellulase
2. B. Amylase
3. C. Protease
4. D. Lactase

3. Pepsin operates efficiently in the stomach, while Trypsin functions in the small intestine. What are their optimum pH environments respectively?

1. A. Pepsin: pH 2.0 | Trypsin: pH 8.5
2. B. Pepsin: pH 7.0 | Trypsin: pH 2.0
3. C. Pepsin: pH 8.5 | Trypsin: pH 6.8
4. D. Pepsin: pH 6.8 | Trypsin: pH 1.5

4. Which enzyme is used in fruit juice manufacturing to clear cloudy suspensions and increase juice yield?

1. A. Pectinase
2. B. Lipase
3. C. Rennet
4. D. Zymase

5. During cheese production, which enzyme causes milk proteins (casein) to coagulate into solid curds?

1. A. Lipase
2. B. Rennet (Chymosin)
3. C. Maltase
4. D. Zymase

6. What happens to an enzyme after it successfully catalyzes a biochemical transformation of a substrate into products?

1. A. It degrades immediately into free amino acids.
2. B. It remains chemically unchanged and is free to bind another substrate molecule.
3. C. It permanently binds to the product molecule.
4. D. It is converted into energy (ATP).

7. Which graph characteristic represents the optimum temperature of an enzyme-catalyzed reaction?

1. A. The lowest point on the temperature curve.
2. B. The peak point on the curve where the reaction rate is at its maximum.
3. C. The flat linear region where the rate remains zero.
4. D. The point where the enzyme begins to denature.

8. What is the role of the enzyme lactase in the food industry?

1. A. Converts glucose into high-fructose corn syrup.
2. B. Hydrolyzes lactose in milk to produce lactose-free dairy products.
3. C. Softens meat by digesting collagen fibers.
4. D. Extracts pectin from citrus peels to clarify fruit juices.

9. At 0°C, what is the status of enzyme activity in living cells?

1. A. Enzymes are completely denatured and permanently inactive.
2. B. Enzymes are inactive due to very low kinetic energy, but remain undamaged.
3. C. Enzymes work at their maximum catalytic rate.
4. D. Active sites undergo structural conformational expansion.

10. Which of the following is an example of a catabolic reaction in living organisms?

1. A. Synthesis of cellulose in plant cell walls
2. B. Cellular respiration breaking down glucose into CO2 and water
3. C. Formation of triglycerides from glycerol and fatty acids
4. D. Polymerization of amino acids into proteins