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Post-Test
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1
Enzymes increase the rate of a reaction by
A)increasing the activation energy.
B)decreasing the activation energy.
C)decreasing the amount of energy required to reach a transition state.
D)increasing the amount of energy required to reach a transition state.
E)stabilizing the reactants so the reaction can take place.
2
Which of the following statements regarding redox reactions is incorrect?
A)Reducing agents accept electrons and oxidizing agents donate electrons
B)Reduction and oxidation must always occur at the same time
C)Reducing agents donate electrons and oxidizing agents accept electrons
D)Redox reactions between molecules are required because electrons do not exist freely in solution
E)The reduction of a molecule energizes the accepting molecule
3
The sum total of all reactions that occur within a cell is referred to as
A)the Central Dogma.
B)respiration.
C)oxidative phosphorylation.
D)metabolism.
E)thermodynamics.
4
A fast rate of product formation in an enzyme-substrate reaction usually implies a low KM due to a high substrate affinity.
A)True
B)False
5
Inorganic ions temporarily bound to an enzyme in order to promote a chemical reaction are known as
A)cotransporters.
B)cofactors.
C)coenzymes.
D)prosthetic groups.
E)inhibitors.
6
A reaction in which products are at a higher energy level than the reactants is described as
A)catabolic.
B)endergonic.
C)exergonic.
D)spontaneous.
E)redox.
7
Some biological catalysts may consist of nucleic acids instead of proteins.
A)True
B)False
8
In the Sidney Altman experiment, why did the RNA subunit of RNase P only show catalytic activity in the presence of high concentrations of Mg2+ (MgCl2)?
A)The MgCl2 was oxidized in the reaction in order to reduce the tRNA molecules
B)The MgCl2 was reduced by the RNA subunit in order to oxidize the tRNA molecules
C)The MgCl2 was required to stabilize the tRNA
D)The MgCl2 helped the RNA subunit of RNase P maintain the proper conformation for catalysis to occur
E)MgCl2 provided the electrochemical gradient required for the RNA subunit to be catalytically active
9
Which of the following statements regarding enzymes is incorrect?
A)Enzymes can temporarily accept reactive groups from substrate molecules
B)Enzymes are optimally active within a narrow range of pH and temperature
C)Enzymes have high specificity for their substrates
D)Enzymes allow reactions to take place that would not naturally occur without them
E)Enzymes may place strain on the bonds of their substrate in order to catalyze a reaction
10
Which of the following is least likely to affect enzyme function?
A)Extreme heat
B)Significant change in pH
C)A sudden influx of ions to the surrounding environment
D)Presence of inhibitors in the surrounding environment
E)An increase in enzyme concentration
11
A sequence of chemical reactions carried out in a cell in order to breakdown or synthesize molecules is known as a
A)Reaction cascade
B)Metabolic pathway
C)Metabolic cascade
D)Endergonic pathway
E)Exergonic pathway
12
Catabolic reactions are exergonic and anabolic reactions are endergonic.
A)True
B)False
13
Which of the following types of proteins does not use ATP for energy in order to carry out function?
A)Ion pump transporter
B)Chaperones
C)Channels
D)Kinases
E)None of these proteins utilize ATP for energy
14
Which of the following does not represent a form of metabolic pathway regulation?
A)Biochemical regulation
B)Competitive inhibition
C)Feedback inhibition
D)Gene regulation
E)Cellular regulation
15
The rate limiting step of a metabolic pathway is fastest step in the pathway.
A)True
B)False
16
Which of the following regarding the recycling of molecules by cells is correct?
A)Recycling of molecules wastes valuable energy
B)mRNA is broken down by proteases
C)Exonucleases degrade RNA starting at the 5’ end and moving toward the 3’ end
D)Eukaryotic cells utilize a proteasome to recycle proteins
E)Prokaryotic cells utilize ubiquitin torecycle proteins
17
Autophagy is a form of endocytosis and is carried out by an autophagosome.
A)True
B)False
18
A chemical reaction with a negative Delta G will
A)be endergonic with a release of free energy.
B)be exergonic and require energy.
C)be spontaneous.
D)favor formation of reactants.
E)not occur.
19
Entropy directly affects enthalpy and therefore affects the amount of energy available to a cell to do work.
A)True
B)False
20
Which of the following is most commonly used by cells to drive endergonic reactions?
A)NADH
B)Hydrolysis
C)Dehydration reactions
D)Free phosphate molecules
E)ATP





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