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Multiple Choice Quiz
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Activation energy is the energy required to
A)Get a reaction started.
B)Synthesize new compounds.
C)Break down incoming molecules.
D)All of the above.

An enzyme is
A)A protein catalyst.
B)Under the direct control of the DNA.
C)A substance that lowers the activation energy.
D)All of the above.

To be functional, an enzyme must
A)Have a specific three-dimensional shape.
B)Attach to a substrate, forming and enzyme-substrate complex.
C)Have a specific binding or attachment site.
D)All of the above.

The induced fit hypothesis states that
A)The substrate will bend or fold to adjust itself to the enzyme.
B)The enzyme will bend or fold to adjust itself to the substrate.
C)The amount of enzyme produced will fit the needs of the substrate.
D)The amount of substrate will be kept constant by the enzyme itself.

According to which of the patterns below are most enzymes named?
A)First the molecule involved; second the type of reaction; third the "-ase" ending.
B)First the type of reaction; second the molecule involved; third the "-ase" ending.
C)First the type of reaction; second some type of description; third the "-ase" ending.
D)The molecule involved and the reaction type are interchangeable - followed by the "-ase" ending.

The term used for an enabling molecule is
A)Turnover regulator.
B)Binding protein.

In general, an enzyme can catalyze __________ reactions per minute.
A)Between 102 and 105
B)Between 103 and 1010
C)Between 103 and 1016
D)Between 104 and 1020

In enzyme-controlled reactions, an increase in temperature will usually
A)Speed up a reaction (without limits).
B)Speed up a reaction (within limits).
C)Slow down a reaction (without limits).
D)Slow down a reaction (within limits).

Which statement(s) is/are true?
A)Enzymes generally have a functional temperature range that is identical to its optimal temperature range.
B)When an enzyme is denatured, its spatial structure is permanently changed.
C)Most enzymes are more sensitive to low temperatures than to high temperatures.
D)All of the above.

Which statement(s) is/are true?
A)The three-dimensional structure of a protein leaves side chains exposed and thus subject to fluctuations in pH.
B)The environmental pH is important in determining the shape of the enzyme.
C)Each enzyme has its own pH range of activity.
D)All of the above.

Mechanisms that ensure that an organism will carry out all metabolic processes in proper sequence are called
A)Control processes.
B)Enzymatic coordination processes.
C)Substrate inhibition processes.
D)Biochemical modulation sequences.

Enzymatic competition occurs when
A)Gene regulator proteins interfere with enzymatic action.
B)Several different enzymes are available to combine with a given substrate.
C)The activator and repressor proteins bind to the substrate instead of the enzyme.
D)Several different substrates are present for a given enzyme.

In negative-feedback inhibition, as the end product increases
A)Some of that end product binds to the substrate.
B)Some of that end product prevents the enzyme from performing properly.
C)Some of that end product binds concurrently to both the substrate and the enzyme.
D)Other genes produce competing enzymes and thus decrease the rate of the reaction.

An inhibitor is a molecule that
A)Attaches itself to an enzyme and interferes with the formation of the enzyme-substrate complex.
B)Attaches itself to a substrate and interferes with the formation of the enzyme-substrate complex.
C)Binds to the enzyme-substrate complex and prevents the release of the end products.
D)Binds to the cell's DNA and prevents the formation of an enzyme.

In competitive inhibition, the competitor
A)Binds to the coenzyme and thus disables the enzyme itself.
B)Interferes with enzyme production.
C)Attaches to the enzyme's active site, preventing the normal substrate from doing so.
D)Acts as a pseudo-enzyme and binds non-functionally to the substrate.

A vitamin sometimes works as a(n):

Competition between enzymes causes:
A)enzymes to denature.
B)decreases in the formation of certain products.
C)each enzyme to function better.
D)rearrangement of active sites.

As the temperature of an enzyme controlled reaction is moderately increased,
A)changes in concentration of enzyme results.
B)fewer transitory molecules are formed.
C)decreases in turnover number occur.
D)more collisions occur so more of them are effective.

Enzyme names frequently
A)include the name of the substrate.
B)ends in -ase.
C)indicate the type of reaction they facilitate.
D)all of the above.

Turnover number:
A)increases as pH increases.
B)does not change relative to concentration of acid or base.
C)increases as optimum conditions are approached.
D)is constant.

High temperatures can
A)denature an enzyme.
B)increase an enzyme's molecular motion.
C)change the protein structure of an enzyme.
D)all of the above.

According to the induced-fit hypothesis
A)the presence of the substrate causes the enzyme to adjust itself to the substrate, this creates stress on substrate bonds.
B)enzymes and substrates fit perfectly together with "lock and key" precision.
C)coenzymes alter the shape of enzyme molecules.
D)inhibitors alter the shape of substrates.

A)are protein molecules.
B)are not altered during a reaction.
C)enable an enzyme to function.
D)all of the above.

Which of the following is true?
A)All enzymes work best at a neutral pH.
B)There is an optimum pH for each specific enzyme.
C)Enzymes work well at any pH higher than optimum.
D)At a low pH, an enzyme needs more kinetic energy to function.

With negative-feedback inhibition, as the number of end products increases,
A)enzyme activity decreases.
B)enzyme activity increases.
C)enzyme/substrate collisions become more effective.
D)inhibitors attach to substrates.

Chemical messengers that tell the cell to decrease the production of a certain protein are
B)gene-repressor proteins.
D)denatured enzymes.

Enzymes function by
A)lowering the activation energy required for a reaction.
B)increasing the temperature of the reaction.
C)providing activation energy to substrate molecules.
D)increasing the production of substrate.

Inhibitor molecules
A)react with end-products.
B)attach to substrates.
C)lower activation energy.
D)attach to enzymes.

To increase the amount of end-product produced in an enzyme facilitated reaction, you could
A)boil the enzyme.
B)add inhibitor.
C)add more substrate.
D)add ice.

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