AP Biology : Understand enzyme structure and purpose

Study concepts, example questions & explanations for AP Biology

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Example Questions

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Example Question #31 : Enzymes

Which of the following would be an example of a catalyst?

Possible Answers:

ATP

Enzymes

Chloroplasts

Mitochondria

Correct answer:

Enzymes

Explanation:

Enzymes are proteins that act as catalysts for reactions. Enzymes are essential in enabling the proper function of human metabolism. If enzymes were absent then chemical traffic throughout the metabolic pathways would become backed up.

Example Question #32 : Enzymes

Enzymes are a type which of the following categories?

Possible Answers:

Sugar

Energy source

Catalyst

Metabolite

Correct answer:

Catalyst

Explanation:

Enzymes are catalytic proteins. Enzymes are essential in proper functioning of metabolism because without them chemical traffic throughout the metabolic pathways would become backed up.

Example Question #33 : Enzymes

Enzymes are a type of which of the following organic molecules?

Possible Answers:

Carbohydrate

Lipid

Sugar

Protein

Correct answer:

Protein

Explanation:

Enzymes are proteins that act as catalysts for metabolism. Enzymes are essential in proper functioning of metabolism because without them chemical traffic throughout the metabolic pathways would become backed up.

Example Question #31 : Enzymes

Which of the following terms can be defined as the initial investment of energy in a reaction that is required to break bonds in the reactant molecules?

Possible Answers:

Initiation energy 

Activation energy

Consumed energy

Reaction energy

Correct answer:

Activation energy

Explanation:

The investment of energy required to start a reaction is called the free energy of activation or activation energy. Activation energy is usually in the form of heat from the surrounding area that molecules in the reaction absorb.

Example Question #32 : Enzymes

Proteins engage in all of the following functions except __________.

Possible Answers:

transport substances into and/or out of cells

store energy in adipose cells

control the rate of reactions and regulate cell processes

comprise muscle tissue

Correct answer:

store energy in adipose cells

Explanation:

Proteins can control rates of reaction and regulate cell processes, form muscle tissue, and transport substances into and out of cells. They do not store energy in fat cells.

Example Question #36 : Enzymes

What does an enzyme do to the activation energy of a given reaction?

Possible Answers:

Enzymes do not change the activation energy

Enzymes lower the activation energy

Enzymes provide the activation energy for reactions

Enzymes raise the activation energy

Correct answer:

Enzymes lower the activation energy

Explanation:

Enzymes lower the activation energy in chemical reactions in cells. They do not alter the composition of products of chemical reactions.

Example Question #37 : Enzymes

What are the reactants of enzyme-catalyzed reactions known as?

Possible Answers:

Inhibitors

Products

Enzymes

Substrates

Correct answer:

Substrates

Explanation:

The reactants of enzyme-catalyzed reactions are known as substrates. Enzymes catalyze formation of products from their substrates. Inhibitors hinder the efficacy of enzymes, thereby decreasing the rate of reactions, and nucleotides are the monomers of DNA and RNA.

Example Question #33 : Enzymes

Which of the following statements regarding exergonic reactions is true?

Possible Answers:

The products contain less energy the reactants

The energy released cannot be used to perform work

They release energy in the form of noise

They do not require energy input before the reaction proceeds

They usually occur instantaneously

Correct answer:

The products contain less energy the reactants

Explanation:

The correct answer to this question is the products contain less energy the reactants.

The products indeed do contain less energy than the reactants because when a spontaneous reaction occurs, it releases energy, which is used to do work. Energy is released in the form of ATP and heat, not noise. Also an input of energy is required before the reaction proceeds, otherwise the reaction does not proceed.

Example Question #34 : Enzymes

How do enzymes increase reaction rates?

Possible Answers:

Increasing activation energy

Increasing temperature

Decreasing activation energy

Increasing pH

Correct answer:

Decreasing activation energy

Explanation:

Enzymes increase the rate of reactions through stabilizing the transition state, which decreases activation energy.

Example Question #40 : Enzymes

Which of the following does not affect enzyme activity?

Possible Answers:

substrate concentration

All of the above

pH

temperature

Correct answer:

All of the above

Explanation:

pH and temperature affect enzyme activity, as there is an optimal pH and temperature for each enzyme, and a pH or temperature too far from the optimal level can cause the enzyme to denature. Substrate concentration affects enzyme activity; increasing substrate concentration will increase the rate of reaction to the point that the enzymes are saturated.

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