B2

Question 1

Describe the basic features of enzymes

Answer 1

Like all other catalysts, enzymes are characterized by two fundamental properties. First, they increase the rate of chemical reactions without themselves being consumed or permanently altered by the reaction. Second, they increase reaction rates without altering the chemical equilibrium between reactants and products.

Question 2

Explain the effect of temperature and pH on enzymes

Answer 2

Temperature: Raising temperature generally speeds up a reaction, and lowering temperature slows down a reaction. However, extreme high temperatures can cause an enzyme to lose its shape (denature) and stop working. pH: Each enzyme has an optimum pH range. Changing the pH outside of this range will slow enzyme activity.

Question 3

Practical on reagents testing for starch, lipids and proteins

Answer 3

To see if there is starch in the food, use iodine solution(yellow/brown), it should turn blue/black for starch to be present. To see if there is lipids in the food, use Sudan III(colourless), it should turn red for lipids to be present. To see if there is protein in the food, use Biuret test(blue), it should turn purple for protein to be present.