Chapter 5: Enzymes

Which of the following substrates is not matched correctly to specific enzyme?

• Substrate: Sucrose

  Enzyme: Sucrase

• Substrate: Maltose

  Enzyme: Maltase

• Substrate: Lipid

  Enzyme: Lipase

• Substrate: Glucose

  Enzyme: Glucase

Which statement is not true about the 'lock and key' hypothesis of enzymatic reactions?

• The enzyme-substrate complex is not stable.

• The substrate combines with the enzyme at the active site.

• The substrate molecule is the 'lock' while the enzyme molecule is the 'key'.

• The surface configuration of the enzyme molecule complements that of the substrate molecule.

Which group of substances interferes with the action of enzymes by binding to the enzyme molecules?

• Cofactors

• Coenzymes

• Inhibitors

• Competitors

If P represents the enzyme, Q represents the substrate and R represents the reaction product, which reaction represents the mechanism of the enzymatic reaction?

• PQ -> P-Q -> PR

• P+Q -> P-Q -> P+R

• P+Q -> P-Q -> R

• P+Q -> P-Q -> P-R -> P+R

Which of the following explains why a small amount of enzyme is able to catalyse a large amount of substrate?

• More enzyme molecules are formed during the reaction.

• Enzymes are not damaged by the reactions and can be reused.

• Enzymes can catalyse reactions in both the forward and reverse directions.

• Enzyme molecules are bigger, hence, they can catalyse several substrate molecules at one time.