Enzyme Function and Catalysis Quiz

Which of the following best describes the active site of an enzyme?

• A rigid structure that cannot change

• The region that binds to substrates

• The part of the enzyme that stores energy

• The site where products are released

Answer explanation

The active site of an enzyme is the region that binds to substrates, facilitating the chemical reaction. It is not a rigid structure and does not store energy or release products.

For an enzyme to catalyze a reaction, which of the following must be true?

• The enzyme must bind to a cofactor.

• The substrate must have a charge opposite to the enzyme.

• The substrate must be compatible in shape and charge with the enzyme’s active site.

• The enzyme must use ATP.

Answer explanation

For an enzyme to catalyze a reaction, the substrate must fit the enzyme's active site in both shape and charge, allowing for effective binding and catalysis. Other options are not universally required.

Tags

NGSS.HS-PS1-2

What role does the enzyme’s active site play in chemical reactions?

• It increases the temperature of the reaction.

• It provides a location for the substrate to bind and react.

• It stores energy for future reactions.

• It breaks down the substrate directly.

Answer explanation

The enzyme's active site is crucial as it provides a specific location for the substrate to bind, facilitating the chemical reaction. This binding lowers the activation energy needed for the reaction to occur.

Which of the following can bind to the active site of an enzyme?

• Allosteric regulators

• Substrates

• Noncompetitive inhibitors

• Coenzymes

Answer explanation

Substrates are the molecules that bind to the active site of an enzyme, allowing the enzyme to catalyze a reaction. Allosteric regulators and noncompetitive inhibitors bind elsewhere, while coenzymes assist but do not bind to the active site.

Enzymes increase the rate of chemical reactions by:

• Raising the temperature of the reaction

• Lowering the activation energy needed for the reaction to occur

• Changing the product of the reaction

• Making the reaction more exergonic

Answer explanation

Enzymes speed up reactions by lowering the activation energy required, allowing reactions to occur more easily without changing the reaction products or making it more exergonic.

Tags

NGSS.HS-LS1-7

What is the role of enzymes in biological systems?

• Enzymes destroy substrates to create products.

• Enzymes provide energy for chemical reactions.

• Enzymes act as biological catalysts by lowering activation energy.

• Enzymes alter the final products of a reaction.

Answer explanation

Enzymes act as biological catalysts by lowering the activation energy required for chemical reactions, thus speeding up the process without being consumed or altering the final products.

How do enzymes regulate biological processes?

• By altering the concentration of substrates

• By increasing the reaction temperature

• By decreasing the time needed to reach equilibrium

• By facilitating reactions without being consumed

Answer explanation

Enzymes regulate biological processes by facilitating reactions without being consumed. They lower activation energy, allowing reactions to occur more efficiently, which is crucial for maintaining life processes.

Which statement is true about enzyme catalysis?

• Enzymes are consumed in the reaction.

• Enzymes can lower the free energy of the products.

• Enzymes speed up reactions without altering the free energy of the reactants.

• Enzymes change the substrate into an active form.

Answer explanation

Enzymes act as catalysts, speeding up reactions without being consumed or altering the free energy of reactants or products. They do not change the energy levels but facilitate the reaction process.

What happens to an enzyme when it is denatured?

• It becomes more efficient.

• Its structure is disrupted, and it can no longer catalyze reactions.

• It binds more easily to its substrate.

• It accelerates the reaction.

Answer explanation

When an enzyme is denatured, its structure is disrupted, which prevents it from properly binding to its substrate and catalyzing reactions. This loss of structure leads to a decrease in enzymatic activity.

Which of the following conditions can cause an enzyme to denature?

• Optimal temperature and pH

• High substrate concentration

• Extreme changes in pH or temperature

• Increasing the enzyme concentration

Answer explanation

Extreme changes in pH or temperature can disrupt the hydrogen bonds and other interactions that maintain an enzyme's structure, leading to denaturation. Optimal conditions do not cause denaturation, while high substrate concentration and enzyme concentration do not either.