General ---------Biology----------------------------------------------------- ------------------Online----------------------------------wilcox@sunline.net Ch. 6  Metabolism of carbohydrates, fats, proteins, nucleic acids

How does an enzyme catalyze a reaction?
     a. by supplying the energy to speed up a reaction
     b. by lowering the energy of activation of a reaction
     c. by lowering the "delta G" of a reaction
     d. by changing the equilibrium of a spontaneous reaction
     e. by increasing the amount of free energy of a reaction

Increasing the substrate concentration in an enzymatic reaction
could overcome which of the following?
     a. denaturing of the enzyme
     b. allosteric inhibition
     c. competitive inhibition
     d. noncompetitive inhibition
     e. insufficient cofactors

A solution of starch at room temperature does not spontaneously
decompose rapidly to a sugar solution because
     a. the starch solution has less free energy than the sugar solution.
     b. the hydrolysis of starch to sugar is endergonic.
     c. the activation energy barrier cannot be surmounted by most of the
        starch molecules.
     d. starch cannot be hydrolyzed in the presence of so much water.
     e. starch hydrolysis is nonspontaneous.

Which of the statements regarding enzymes is false?
     a. Enzymes are proteins that function as catalysts.
     b. Enzymes display specificity for certain molecules to which they
        attach.
     c. Enzymes provide activation energy for the reactions they
        catalyze.
     d. The activity of enzymes can be regulated by factors in their
        immediate environment.
     e. An enzyme may be used many times over for a specific reaction.

Which of the following statements regarding enzymes is true? Enzymes
     a. have no effect on the rate of a reaction.
     b. increase the rate of reaction.
     c. change the direction of chemical reactions.
     d. are permanently altered by the reactions they catalyze.
     e. prevent changes in substrate concentrations from having an effect
        on reaction rates.

According to the induced fit hypothesis of enzyme function, which of
the following is the most accurate description of the mechanism involved?
     a. The binding of the substrate depends on the shape of the active
        site.
     b. Some enzymes become denatured when activators bind to the
        substrate.
     c. A competitive inhibitor can out compete the substrate for the
        active site.
     d. The binding of the substrate changes the shape of the enzyme
        slightly and may stress or bend substrate bonds.
     e. The active site creates a micro environment ideal for the
        reaction.

. All of the following statements regarding enzymes are true EXCEPT
     a. Enzymes are carbohydrates that function as agents that change the
        rate of reaction without being consumed in the reaction.
     b. Enzymes allow molecules to react in metabolism by lowering
        activation energies.
     c. Each type of enzyme has a uniquely shaped active site, that gives
        it specificity.
     d. Enzymes are very sensitive to environmental conditions that
        influence the weak chemical bonds responsible for their three-
        dimensional structure.
     e. Some enzymes change shape when regulator molecules, either
        activators or inhibitors, bind to specific allosteric receptor
        sites.

answers