chpt 8 Flashcards


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1

The second law of thermodynamics holds that

A) matter can be neither created nor destroyed B) energy can be neither created nor destroyed. C) energy of one form is converted to a less concentrated whenever energy is transformed or Transferred D) entropy decreases with time.

C

2

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?

A) catalysis B) metabolism C) anabolism D) dehydration E) catabolism

E

3

Whenever energy is transformed, there is always an increase in the

A) free energy of the system. B) free energy of the universe. C) entropy of the system. D) entropy of the universe. E) enthalpy of the universe.

D

4

Which of the following is an example of potential rather than kinetic energy?

A) the muscle contractions of a person mowing grass B) water rushing over Niagara Falls C) light flashes emitted by a firefly D) a molecule of glucose E) the flight of an insect foraging for food

D

5

Which of the following is most similar in structure to ATP?

A) a pentose sugar B) a DNA nucleotide C) an RNA nucleotide D) a phospholipid E) an amino acid with three phosphate groups attached

C

6

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

A) The reaction is faster than the same reaction in the absence of the enzyme. B) The free energy change of the reaction is opposite from the reaction that occurs in the absence of the enzyme. C) The reaction always goes in the direction toward chemical equilibrium. D) Enzyme-catalyzed reactions require energy to activate the enzyme. E) Enzyme-catalyzed reactions release more free energy than noncatalyzed reactions.

A

7

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following? A) denaturization of the enzyme B) allosteric inhibition C) competitive inhibition D) saturation of the enzyme activity E) insufficient cofactors

C

8

Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as a(n)

A) competitive inhibitor of the enzyme. B) noncompetitive inhibitor of the enzyme. C) allosteric activator of the enzyme. D) cofactor necessary for enzyme activity. E) coenzyme derived from a vitamin.

D

9

When sodium chloride (table salt) crystals dissolve in water, the temperature of the solution decreases. This means that, for dissociation of Na+ and Cl- ions,

A) the change in enthalpy (DH) is negative. B) the change in enthalpy (DH) is positive, but the change in entropy is greater. C) the reaction is endergonic, because it absorbs heat. D) the reaction must be coupled to an exergonic reaction.

B

10

Which enzymes may translocate from the cytoplasm to associate with the cytoplasmic face of the plasma membrane in response to a signal?

A) ion channels B) active transport proteins C) phospholipid hydrolases D) ATP synthases E) motor proteins

C