Introduction to Energy

The cellular process of breaking down large molecules into smaller ones is defined as

• a. metabolism

• b. anabolism

• c. dehydration

• d. catabolism

Anabolic pathways share which of the following characteristics?

• a. They are not dependent on enzymes.

• b. They are usually spontaneous chemical reactions that do not require an input of energy.

• c. They consume energy to synthesize polymers from monomers.

• d. They release energy as they degrade polymers to monomers.

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as is to

• a. exergonic; spontaneous

• b. exergonic; endergonic

• c. free energy; entropy

• d. work; energy

Which of the following types of reactions would decrease the entropy within a cell?

• a. anabolic reactions

• b. hydrolysis

• c. catabolic reactions

• d. digestion

Which of the following reactions release energy?

• a. endergonic reactions

• b. dehydration reactions

• c. hydrolysis reactions

• d. formation of water from hydrogen and hydroxyl ions

A chemical reaction that has a positive ΔG is best described as

• a. endergonic

• b. at equilibrium

• c. spontaneous

• d. exergonic

Which of the following statements best describes the critical role that ATP plays in cellular metabolism?

• a. The covalent bond on the terminal phosphate of ATP is particularly strong, so it releases extra energy when hydrolyzed.

• b. It is one of the four building nucleotides required for DNA synthesis.

• c. ATP hydrolysis provides the energy used to power exergonic reactions in the cell.

• d. ATP serves as an energy shuttle in the cell, coupling exergonic and endergonic reactions.

Which of the following statements about enzyme-catalyzed reactions is true?

• a. The free-energy change of the reaction is greater than when the same reaction occurs in the absence of an enzyme.

• b. The rate of the reaction is greater than when the same reaction occurs in the absence of an enzyme.

• c. The activation energy required for the reaction to proceed is greater than when the same reaction occurs in the absence of an enzyme.

• d. Energy from ATP is required to activate the enzyme before it can catalyze the reaction.

In most exergonic reactions, before products can be formed, the reactants must first overcome a thermodynamic barrier known as the

• a. entropy of the reaction

• b. energy conservation of the reaction

• c. chemical equilibrium of the reaction

• d. activation energy of the reaction

The active site of an enzyme is the region that

• a. binds allosteric regulators of the enzyme

• b. binds substrates for the enzyme

• c. binds noncompetitive inhibitors of the enzyme

• d. is blocked by the presence of a coenzyme or a cofactor