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.
O
B.
S
C.
N
D.
H
E.
C
Question #2
Which of the following statements is not true:
A.
Maintaining a steady state is coupled to a flux of metabolites
B.
Organisms use metabolic processes to obtain the free energy they need to carry out various functions
C.
Chemotrophs rely on chemical compounds derived from other organisms
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.
isolated systems
B.
closed systems
C.
thermally isolated
D.
open 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.
ether
B.
aldehyde
C.
ester
D.
carboxylic acid
E.
ketone
Question #6
The four covalent bonds in methane (CH4) are arranged around carbon to give which one of the following geometries?
A.
Linear
B.
Trigonal planar
C.
Tetrahedral
D.
Trigonal pyramidal
E.
Trigonal bipyramidal
Question #7
Stereoisomers that are nonsuperimposable mirror images of each other are known as:
A.
diastereoisomers
B.
anomers
C.
geometric isomers
D.
enantiomers
E.
cis-trans isomers
Question #8
Humans maintain a nearly constant level of hemoglobin by continually synthesizing and degrading it. This is an example of a(n):
A.
equilibrium state
B.
dynamic steady state
C.
exergonic change
D.
waste of energy
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.
An object suspended in the air has more energy than an object lying on the ground
B.
Energy can be converted from one form to another
C.
The energy stored in chemical bonds is referred to as kinetic energy
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 difference between the energy released by bond formation and the energy consumed by bond cleavage during a chemical reaction
B.
The energy consumed when chemical bonds are broken 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.
The internal energy of the universe is constant
B.
When an isolated system undergoes a spontaneous change, the entropy of the system will increase
C.
At absolute zero, the entropy of a perfect crystal is considered to be zero
D.
Energy can be neither created nor destroyed
Question #13
Which one of the following statements regarding a dynamic equilibrium is false?
A.
At equilibrium, there is no net change in the system
B.
At equilibrium, the concentration of reactants and products stays the same
C.
At equilibrium, the rates of the forward and back reactions are identical
D.
At equilibrium, the forward and back reactions cease to occur
Question #14
At equilibrium, the concentrations of the reactants and products will be equal.
A.
FALSE
B.
TRUE
Question #15
A large value of Keq tells us which of the following?
A.
The reaction lies to the left
B.
The reaction lies in the middle
C.
The reaction lies to the right
Question #16
Which one of the following statements regarding chemical equilibria is false?
A.
At equilibrium, ΔG = 0
B.
Catalysts do not alter the position of equilibrium: they do not shift the equilibrium to the left or right
C.
If the equilibrium constant is very large, ΔG is positive
D.
If ΔG for a reaction is negative, the forward reaction happens spontaneously
Question #17
When the system A + B --> C + D is at equilibrium,
A.
the sum of the concentrations of A and B must equal the sum of the concentrations of C and D.
B.
the forward reaction has stopped.
C.
both the forward and the reverse reactions have stopped.
D.
neither the forward nor the reverse reaction has stopped
E.
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.
endergonic
B.
endothermic
C.
exergonic
D.
at equilibrium
E.
exothermic
Question #19
Based on the equilibrium constants given, in which of these reactions are the products most favored over the reactants?
A.
Keq = 0.0
B.
Keq = 3.5
C.
Keq = 0.002
D.
Keq =6.0×10^-4
Question #20
Which of the statements regarding the effect of reactant or product concentration changes on equilibrium is false?
A.
Adding a reactant always shifts a reversible reaction in the direction of reactants.
B.
Removing a product shifts a reversible reaction in the direction of formation of products.
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.
endothermic
B.
at equilibrium
C.
exothermic
D.
endergonic
E.
exergonic
Question #22
Reactions that have positive standard free energy changes (ΔGo > 0) can be made to occur in cells by
A.
coupling them with exergonic reactions via a common intermediate
B.
manipulating the concentrations of products and reactants such that ΔG < 0
C.
coupling them to the hydrolysis of ATP
D.
all of the above
Question #23
Which of the following is true for all exergonic reactions?
A.
The reactions are rapid
B.
A net input of energy from the surroundings is required for the reactions to proceed
C.
The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants
D.
The products have more total energy than the reactants
E.
The reaction proceeds with a net release of free energy
Question #24
Which of the following is CORRECT for an exergonic reaction?
A.
products have less energy than reactants
B.
products have more 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 irreversible
B.
is considered reversible
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 neutralization reaction with equal number of moles of an acid and a base.
C.
A steady state in which matter is entering and leaving the system at a constant rate.
D.
A state of balance in a chemical reaction where the speed of the forward reaction is unequal to the reverse reaction.
Question #28
In case of nonspontaneous reaction, the reaction that is favored is
A.
forward
B.
reverse
C.
Reaction stops
D.
both forward and reverse
Question #29
When value of Keq is greater than 1, than reaction is
A.
backward
B.
spontaneous
C.
nonspontaneous
D.
forward
Question #30
ΔG in case of spontaneous reaction is
A.
zero
B.
positive
C.
infinite
D.
negative
Question #31
Enthalpy has something to do with the first Law of Thermodynamics.
A.
FALSE
B.
TRUE
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 change is the proportion of the enthalpy change of a reaction that is used to increase the entropy
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 is represented by the symbol G
Question #34
Energy requiring metabolic pathways that yield complex molecules from simpler precursors are:
A.
amphibolic
B.
catabolic
C.
anabolic
D.
autotrophic
E.
heterotrophic
Question #35
Enzymes are biological catalysts that enhance the rate of a reaction by:
A.
decreasing the activation energy
B.
increasing the activation energy
C.
increasing the amount of free energy released
D.
increasing the energy of the transition state
E.
decreasing the amount of free energy released
Question #36
Which explanation best describes why a catalyst does not affect the position of equilibrium?
A.
Not all chemical reactions respond to catalysts
B.
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.
C.
A catalyst will increase the activation energy in both directions; therefore, no shift in the position of equilibrium will result.
D.
Equilibrium constants are not affected by adding a catalyst since no shift in the position of equilibrium occurs.
Question #37
What effect does a catalyst have on a reaction?
A.
It increases the rate
B.
It increases the yield
C.
It increases the activation energy
D.
It increases the heat of reaction
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.
FALSE
B.
TRUE
Question #41
A chemical process that releases energy is called exergonic.
A.
TRUE
B.
FALSE
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.
FALSE
B.
TRUE
Question #48
If Keq = 1, [products] = [reactants] at equilibrium.
A.
TRUE
B.
FALSE
Question #49
Keq = 1 means that neither reactants nor products are favored at equilibrium.
A.
FALSE
B.
TRUE
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