Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question.
|
|
|
1.
|
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 | | |
|
|
|
2.
|
Which
of the following is a statement of the first law of thermodynamics? a. | Energy cannot be
created or destroyed. | b. | The entropy of the universe is
decreasing. | c. | The entropy of the universe is
constant. | d. | Kinetic energy is stored energy that results from the specific
arrangement of matter. | e. | Energy cannot be transferred or
transformed. | | |
|
|
|
3.
|
Which
of the following forms of energy is least available to accomplish cellular work? a. | light
energy | b. | electrical energy | c. | thermal energy
(heat) | d. | mechanical energy | e. | potential
energy | | |
|
|
|
4.
|
Which
of the following is true for all exergonic reactions? a. | The products
have more total energy than the reactants. | b. | The reaction proceeds with a net release of free
energy. | c. | Some reactants will be converted to
products. | d. | A net input of energy from the surroundings is required for the
reactions to proceed. | e. | The reactions are nonspontaneous. | | |
|
|
|
5.
|
Which
of the following is most similar in structure to ATP? a. | an anabolic
steroid | b. | a DNA helix | c. | RNA
nucleotides | d. | an amino acid with three phosphate groups
attached | e. | a phospholipid | | |
|
|
|
6.
|
How
can one increase the rate of a chemical reaction? a. | Increase the activation energy
needed. | b. | Cool the reactants. | c. | Decrease the
concentration of the reactants. | d. | Add a catalyst. | e. | Increase the
entropy of the reactants. | | |
|
|
|
7.
|
A
solution of starch at room temperature does not readily decompose to form a solution of simple sugars
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 for this reaction cannot be
surmounted. | d. | starch cannot be hydrolyzed in the presence of so much
water. | e. | starch hydrolysis is nonspontaneous. | | |
|
|
|
8.
|
Which
of the following statements regarding enzymes is true? a. | Enzymes decrease
the free energy change of a reaction. | b. | Enzymes increase the rate of a
reaction. | c. | Enzymes change the direction of chemical
reactions. | d. | Enzymes are permanently altered by the reactions they
catalyze. | e. | Enzymes prevent changes in substrate
concentrations. | | |
|
|
|
9.
|
The
active site of an enzyme is the region that a. | binds allosteric regulators of the
enzyme. | b. | is involved in the catalytic reaction of the
enzyme. | c. | binds the products of the catalytic
reaction. | d. | is inhibited by the presence of a coenzyme or a
cofactor. | e. | both A and B | | |
|
|
|
10.
|
According to the induced fit hypothesis of enzyme catalysis, which of the following is
CORRECT? a. | The binding of
the substrate depends on the shape of the active site. | b. | Some enzymes
change their structure when activators bind to the enzyme. | c. | A competitive
inhibitor can outcompete the substrate for the active site. | d. | The binding of
the substrate changes the shape of the enzyme's active site. | e. | The active site
creates a microenvironment ideal for the reaction. | | |
|
|
|
11.
|
As
temperature decreases, the rate of an enzyme-catalyzed reaction also decreases. Which of the
following explain(s) why this occurs? a. | Fewer substrates have sufficient energy to get over the
activation energy barrier. | b. | Motion in the active site of the enzyme is slowed, thus slowing
the catalysis of the enzyme. | c. | The motion of the substrate molecules decreases, allowing them
to bind more easily to the active site. | d. | A and B only | e. | A, B, and
C | | |
|
|
|
12.
|
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 | | |
|
|
|
13.
|
What
is a nonprotein "helper" of an enzyme molecule called? a. | accessory
enzyme | b. | allosteric group | c. | coenzyme | d. | functional group | e. | enzyme
activator | | |
|
|
|
14.
|
Which
of the following is true of enzymes? a. | Enzymes may require a nonprotein cofactor or ion for catalysis
to take place. | b. | Enzyme function is reduced if the three-dimensional structure
or conformation of an enzyme is altered. | c. | Enzyme function is influenced by physical and chemical
environmental factors such as pH and temperature. | d. | Enzymes increase
the rate of chemical reaction by lowering activation energy barriers. | e. | All of the above
are true of enzymes. | | |
|
|
|
15.
|
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. | | |
|