Macro-nutrients and Enzymes

Which element is present in proteins but not in carbohydrates?

• Nitrogen

• Hydrogen

• Oxygen

Name the elements that are present in fats and oils.

• Carbon and hydrogen only

• Carbon and oxygen only

• Carbon, hydrogen and oxygen

Which of the following result yield a positive test for starch?

• Orange-brown bromine water is decolourised

• Iodine solution turns blue-black

• Biuret reagent turns purple

What are lipids made from?

• Amino acids

• Simple sugars

• Fatty acids and glycerol

A red colour forms when a solution is heated with Benedict's reagent. What could this solution contain?

• Glucose

• Sucrose

• Lipase

What is glycogen made from?

• Glucagon

• Glucose

• Glycerol

What are enzymes?

• Proteins that act as biological catalysts

• Living organisms that act as biological catalysts

• Complex carbohydrates that act as biological catalysts

What happens to an enzyme when its active site changes shape irreversibly?

• It is killed

• It is denatured

• It is diffused

What happens to the activity of an enzyme as the temperature is increased?

• It increases

• It decreases

• It increases to a maximum then decreases

Which statement about the optimum pH for an enzyme is correct?

• It is the pH at which the enzyme's activity is greatest

• It is the same for all enzymes

• It is the pH at which the enzyme cannot be damaged by heat