Chem 221 - Biochemistry for Science Majors » Fall 2021 » L1 The Foundation of Biochemistry
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Question #1
Which one of the following is not among the four most abundant elements in living organisms?
A.
H
B.
N
C.
S
D.
C
E.
O
Question #2
Which of the following statements is not true:
A.
Chemotrophs rely on chemical compounds derived from other organisms
B.
Organisms use metabolic processes to obtain the free energy they need to carry out various functions
C.
Maintaining a steady state is coupled to a flux of metabolites
D.
All living organisms try to be in equilibrium
E.
A living cell tries to maintain a steady state
Question #3
Living organisms are:
A.
thermally isolated
B.
closed systems
C.
open systems
D.
isolated systems
E.
none of the above
Question #4
The reactions of molecules
A.
are the reactions of the functional groups
B.
require an enzyme in all cases
C.
are independent of the functional groups
D.
all of the above
Question #5
If the H from the OH group in CH3-OH is removed and replaced with a METHYL group, what family will the molecule then belong to?
A.
carboxylic acid
B.
aldehyde
C.
ester
D.
ether
E.
ketone
Question #6
The four covalent bonds in methane (CH4) are arranged around carbon to give which one of the following geometries?
A.
Tetrahedral
B.
Trigonal bipyramidal
C.
Trigonal planar
D.
Trigonal pyramidal
E.
Linear
Question #7
Stereoisomers that are nonsuperimposable mirror images of each other are known as:
A.
enantiomers
B.
cis-trans isomers
C.
diastereoisomers
D.
geometric isomers
E.
anomers
Question #8
Humans maintain a nearly constant level of hemoglobin by continually synthesizing and degrading it. This is an example of a(n):
A.
waste of energy
B.
exergonic change
C.
dynamic steady state
D.
equilibrium state
E.
free-energy change
Question #9
The formation of a chemical bond releases energy.
A.
FALSE
B.
TRUE
Question #10
Which one of the following statements regarding energy is false?
A.
Energy can be converted from one form to another
B.
The energy stored in chemical bonds is referred to as kinetic energy
C.
An object suspended in the air has more energy than an object lying on the ground
D.
The total energy in a chemical universe (a system and its surroundings) is constant
Question #11
Which one of the following statements best describes the enthalpy change of a reaction?
A.
The energy consumed when chemical bonds are broken during a chemical reaction
B.
The difference between the energy released by bond formation and the energy consumed by bond cleavage during a chemical reaction
C.
The energy released when chemical bonds are formed during a chemical reaction
D.
The increase in disorder of the system as a reaction proceeds
Question #12
Which of the following statements best describes the Second Law of Thermodynamics?
A.
When an isolated system undergoes a spontaneous change, the entropy of the system will increase
B.
Energy can be neither created nor destroyed
C.
At absolute zero, the entropy of a perfect crystal is considered to be zero
D.
The internal energy of the universe is constant
Question #13
Which one of the following statements regarding a dynamic equilibrium is false?
A.
At equilibrium, the forward and back reactions cease to occur
B.
At equilibrium, the rates of the forward and back reactions are identical
C.
At equilibrium, there is no net change in the system
D.
At equilibrium, the concentration of reactants and products stays the same
Question #14
At equilibrium, the concentrations of the reactants and products will be equal.
A.
TRUE
B.
FALSE
Question #15
A large value of Keq tells us which of the following?
A.
The reaction lies to the right
B.
The reaction lies to the left
C.
The reaction lies in the middle
Question #16
Which one of the following statements regarding chemical equilibria is false?
A.
If ΔG for a reaction is negative, the forward reaction happens spontaneously
B.
At equilibrium, ΔG = 0
C.
If the equilibrium constant is very large, ΔG is positive
D.
Catalysts do not alter the position of equilibrium: they do not shift the equilibrium to the left or right
Question #17
When the system A + B --> C + D is at equilibrium,
A.
the reverse reaction has stopped.
B.
both the forward and the reverse reactions have stopped.
C.
the sum of the concentrations of A and B must equal the sum of the concentrations of C and D.
D.
the forward reaction has stopped.
E.
neither the forward nor the reverse reaction has stopped
Question #18
If heat energy is absorbed by the system during a chemical reaction, the reaction is said to be:
A.
exothermic
B.
endergonic
C.
endothermic
D.
exergonic
E.
at equilibrium
Question #19
Based on the equilibrium constants given, in which of these reactions are the products most favored over the reactants?
A.
Keq =6.0×10^-4
B.
Keq = 0.002
C.
Keq = 0.0
D.
Keq = 3.5
Question #20
Which of the statements regarding the effect of reactant or product concentration changes on equilibrium is false?
A.
Removing a product shifts a reversible reaction in the direction of formation of products.
B.
Adding a reactant always shifts a reversible reaction in the direction of reactants.
C.
Adding a product causes a reversible reaction to shift in the direction of the formation of the reactants.
D.
Removing a reactant always shifts a reversible reaction in the direction of reactants.
Question #21
If the free energy change (ΔG) for a reaction is –46.11 kJ/mol, the reaction is:
A.
exergonic
B.
endergonic
C.
endothermic
D.
exothermic
E.
at equilibrium
Question #22
Reactions that have positive standard free energy changes (ΔGo > 0) can be made to occur in cells by
A.
coupling them to the hydrolysis of ATP
B.
manipulating the concentrations of products and reactants such that ΔG < 0
C.
coupling them with exergonic reactions via a common intermediate
D.
all of the above
Question #23
Which of the following is true for all exergonic reactions?
A.
The reactions are rapid
B.
The reaction proceeds with a net release of free energy
C.
The products have more total energy than the reactants
D.
The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants
E.
A net input of energy from the surroundings is required for the reactions to proceed
Question #24
Which of the following is CORRECT for an exergonic reaction?
A.
products have more energy than reactants
B.
products have less energy than reactants
C.
less activation energy is needed than for an endergonic reaction
D.
more activation energy is needed than for an endergonic reaction
Question #25
A spontaneous process
A.
is considered reversible
B.
is considered irreversible
Question #26
When a system is at equilibrium, ________________.
A.
the forward process is spontaneous but the reverse process is not
B.
the free energy change is 0
C.
both forward and reverse processes have stopped
D.
the reverse process is spontaneous but the forward process is not.
Question #27
What is chemical equilibrium?
A.
A chemical reaction in which the forward and reverse reactions are occurring at the same time and at the same rate.
B.
A state of balance in a chemical reaction where the speed of the forward reaction is unequal to the reverse reaction.
C.
A neutralization reaction with equal number of moles of an acid and a base.
D.
A steady state in which matter is entering and leaving the system at a constant rate.
Question #28
In case of nonspontaneous reaction, the reaction that is favored is
A.
both forward and reverse
B.
reverse
C.
Reaction stops
D.
forward
Question #29
When value of Keq is greater than 1, than reaction is
A.
nonspontaneous
B.
forward
C.
spontaneous
D.
backward
Question #30
ΔG in case of spontaneous reaction is
A.
positive
B.
negative
C.
infinite
D.
zero
Question #31
Enthalpy has something to do with the first Law of Thermodynamics.
A.
TRUE
B.
FALSE
Question #32
Which of the following terms describes a reaction in which there is a net transfer of energy from a system to its surroundings - that is, where more energy is released by bond formation than is consumed by bond cleavage?
A.
Exothermic
B.
Endothermic
Question #33
Which of the following statements regarding the Gibbs free energy change for a reaction is false?
A.
The Gibbs free energy is represented by the symbol G
B.
If the Gibbs free energy change for a reaction is negative, the reaction happens spontaneously
C.
A reaction with a negative Gibbs free energy change of reaction is called an exergonic reaction
D.
The Gibbs free energy change is the proportion of the enthalpy change of a reaction that is used to increase the entropy
Question #34
Energy requiring metabolic pathways that yield complex molecules from simpler precursors are:
A.
catabolic
B.
anabolic
C.
heterotrophic
D.
autotrophic
E.
amphibolic
Question #35
Enzymes are biological catalysts that enhance the rate of a reaction by:
A.
increasing the activation energy
B.
decreasing the activation energy
C.
increasing the amount of free energy released
D.
decreasing the amount of free energy released
E.
increasing the energy of the transition state
Question #36
Which explanation best describes why a catalyst does not affect the position of equilibrium?
A.
The position of equilibrium is not affected by adding a catalyst since a catalyst speeds up both the forward and back reactions by exactly the same amount.
B.
A catalyst will increase the activation energy in both directions; therefore, no shift in the position of equilibrium will result.
C.
Equilibrium constants are not affected by adding a catalyst since no shift in the position of equilibrium occurs.
D.
Not all chemical reactions respond to catalysts
Question #37
What effect does a catalyst have on a reaction?
A.
It increases the heat of reaction
B.
It increases the activation energy
C.
It increases the yield
D.
It increases the rate
Question #38
In a closed system, only an exchange of matter occurs between the system and the surrounding
A.
FALSE
B.
TRUE
Question #39
In an isolated system, only exchange of energy occurs between the system and the surrounding.
A.
TRUE
B.
FALSE
Question #40
A process tends to occur spontaneously only if ΔG is negative.
A.
TRUE
B.
FALSE
Question #41
A chemical process that releases energy is called exergonic.
A.
FALSE
B.
TRUE
Question #42
When Keq > 1, the formation of reactants is favored
A.
FALSE
B.
TRUE
Question #43
At equilibrium, the free energy change equals 1
A.
TRUE
B.
FALSE
Question #44
When Keq > > 1, ΔG° is large and negative
A.
FALSE
B.
TRUE
Question #45
ΔG° tells us fast the equilibrium will be achieved
A.
TRUE
B.
FALSE
Question #46
The higher the activation energy for a reaction, the fastest is the reaction
A.
FALSE
B.
TRUE
Question #47
Anabolism is the breaking down of macromolecules to release energy.
A.
TRUE
B.
FALSE
Question #48
If Keq = 1, [products] = [reactants] at equilibrium.
A.
FALSE
B.
TRUE
Question #49
Keq = 1 means that neither reactants nor products are favored at equilibrium.
A.
TRUE
B.
FALSE
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