Enzymes

What is the function of enzymes in biological systems?

• To store energy
• To slow down reactions
• To act as biological catalysts
• To provide structural support

Answer explanation

Enzymes act as biological catalysts that speed up chemical reactions.

Which part of an enzyme binds to the substrate?

• Binding site
• Contact point
• Active site
• Substrate channel

Answer explanation

The active site is where the substrate binds to the enzyme.

What is the effect of very high temperatures on enzymes?

• They become more efficient
• They stop working permanently
• They denature
• They speed up reactions

Answer explanation

High temperatures denature enzymes, changing their shape.

What does the 'lock and key' model refer to?

• Protein synthesis
• Cell structure
• Enzyme-substrate interaction
• DNA replication

Answer explanation

It refers to the specific fit between an enzyme and its substrate.

Which type of macromolecule are enzymes made from?

• Lipids
• Carbohydrates
• Proteins
• Nucleic acids

Answer explanation

Enzymes are made of proteins.

Which of these enzymes breaks down proteins?

• Amylase
• Lipase
• Protease
• Cellulase

Answer explanation

Protease breaks down proteins into amino acids.

What is the product of starch digestion by amylase?

• Fatty acids
• Glycerol
• Sugars
• Amino acids

Answer explanation

Amylase breaks starch into simple sugars.

Which factor does NOT affect enzyme activity?

• Temperature
• pH
• Light intensity
• Substrate concentration

Answer explanation

Light intensity does not influence enzyme activity.

At what temperature do most human enzymes work best?

• 0¬∞C
• 25¬∞C
• 37¬∞C
• 100¬∞C

Answer explanation

37°C is the normal body temperature where human enzymes are most active.

What happens to the rate of enzyme activity at temperatures below the optimum?

• It increases rapidly
• It stops completely
• It slows down
• It stays the same

Answer explanation

Low temperatures slow down enzyme activity due to reduced kinetic energy.