Chem 221 - Biochemistry for Science Majors » Fall 2021 » L15 Bioenergetics Part 1 of 2
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Question #1
If the ∆G'° of the reaction A -> B is –40 kJ/mol, under standard conditions the reaction:
A.
will never reach equilibrium
B.
is at equilibrium
C.
will proceed at a rapid rate
D.
will not occur spontaneously
E.
will proceed spontaneously from A to B
Question #2
When a mixture of 3-phosphoglycerate and 2-phosphoglycerate is incubated at 25 °C with phosphoglycerate mutase until equilibrium is reached, the final mixture contains six times as much 2-phosphoglycerate as 3-phosphoglycerate. Which one of the following statements is most nearly correct, when applied to the reaction as written? (R = 8.315 J/mol·K; T = 298 K) 3-Phosphoglycerate -> 2-phosphoglycerate
A.
∆G'° is –4.44 kJ/mol.
B.
∆G'°is +12.7 kJ/mol.
C.
∆G'° cannot be calculated from the information given.
D.
∆G'°is incalculably large and positive.
E.
∆G'° is zero.
Question #3
When a mixture of glucose 6-phosphate and fructose 6-phosphate is incubated with the enzyme phosphohexose isomerase (which catalyzes the interconversion of these two compounds) until equilibrium is reached, the final mixture contains twice as much glucose 6-phosphate as fructose 6-phosphate. Which one of the following statements is best applied to this reaction outlined below? (R = 8.315 J/mol·K; T = 298 K) Glucose 6-phosphate -> fructose 6-phosphate
A.
∆G'° is +1.72 kJ/mol.
B.
∆G'° is –1.72 kJ/mol.
C.
∆G'° is zero.
D.
∆G'° is incalculably large and positive.
E.
∆G'° is incalculably large and negative.
Question #4
Hydrolysis of 1 M glucose 6-phosphate catalyzed by glucose 6-phosphatase is 99% complete at equilibrium (i.e., only 1% of the substrate remains). Which of the following statements is most nearly correct? (R = 8.315 J/mol·K; T = 298 K)
A.
∆G'° is –5 kJ/mol.
B.
∆G'° is 0 kJ/mol.
C.
∆G'° cannot be determined from the information given.
D.
∆G'° is +11 kJ/mol.
E.
∆G'° is –11 kJ/mol.
Question #5
The reaction A + B -> C has a ∆G'° of –20 kJ/mol at 25° C. Starting under standard conditions, one can predict that:
A.
C will rapidly break down to A + B.
B.
at equilibrium, the concentration of B will exceed the concentration of A.
C.
at equilibrium, the concentration of C will be much greater than the concentration of A or B.
D.
at equilibrium, the concentration of C will be less than the concentration of A.
E.
when A and B are mixed, the reaction will proceed rapidly toward formation of C.
Question #6
For the following reaction, ∆G'° = +29.7 kJ/mol. L-Malate + NAD+ -> oxaloacetate + NADH The reaction as written:
A.
can occur in a cell only if it is coupled to another reaction for which ∆G'° is positive.
B.
cannot occur because of its large activation energy.
C.
may occur in cells at some concentrations of substrate and product.
D.
can never occur in a cell.
E.
can occur only in a cell in which NADH is converted to NAD+ by electron transport.
Question #7
During glycolysis, glucose 1-phosphate is converted to fructose 6-phosphate in two successive reactions: Glucose 1-phosphate -> glucose 6-phosphate ∆G'° = –7.1 kJ/mol Glucose 6-phosphate -> fructose 6-phosphate ∆G'° = +1.7 kJ/mol ∆G'° for the overall reaction is:
A.
+8.8 kJ/mol.
B.
–8.8 kJ/mol.
C.
+5.4 kJ/mol.
D.
–7.1 kJ/mol.
E.
–5.4 kJ/mol.
Question #8
The standard free-energy changes for the reactions below are given. Phosphocreatine -> creatine + Pi ∆G'° = –43.0 kJ/mol ATP -> ADP + Pi ∆G'° = –30.5 kJ/mol What is the overall ∆G'° for the following reaction? Phosphocreatine + ADP -> creatine + ATP
A.
+73.5 kJ/mol
B.
–12.5 kJ/mol
C.
∆G'° cannot be calculated without Keq'.
D.
+12.5 kJ/mol
E.
–73.5 kJ/mol
Question #9
All of the following contribute to the large, negative, free-energy change upon hydrolysis of “high-energy” compounds except:
A.
stabilization of products by extra resonance forms.
B.
electrostatic repulsion in the reactant.
C.
stabilization of products by ionization.
D.
stabilization of products by solvation.
E.
low activation energy of forward reaction.
Question #10
The hydrolysis of ATP has a large negative ∆G'°; nevertheless it is stable in solution due to:
A.
the hydrolysis reaction being endergonic.
B.
entropy stabilization.
C.
ionization of the phosphates.
D.
resonance stabilization.
E.
the hydrolysis reaction having a large activation energy.
Question #11
Which of the following serves as the “chemical currency” of metabolism?
A.
NADPH
B.
ATP
C.
glucose
D.
acetyl CoA
E.
NADH
Question #12
When a reaction proceeds with a net release of free energy, the free-energy change has a positive value and the reaction is said to be exergonic.
A.
FALSE
B.
TRUE
Question #13
When, during a chemical reaction, the system changes so as to possess more free energy, the free-energy change has a positive value and the reaction is said to be exergonic.
A.
TRUE
B.
FALSE
Question #14
If a reaction is exergonic converting reactants to products, then it's be endergonic converting products to reactants.
A.
FALSE
B.
TRUE
Question #15
A spontaneous reactions has a large equilibrium constant.
A.
FALSE
B.
TRUE
Question #16
A value of equilibrium constant equal to 4.3 x 10-2 corresponds to a non-spontaneous reaction.
A.
TRUE
B.
FALSE
Question #17
The standard free energy change is often measured in kjoules or kcalories.
A.
TRUE
B.
FALSE
Question #18
The conditions inside a cell or organism can be very different from these standard conditions, so ∆G values for biological reactions in vivo may vary widely from their standard free energy change (ΔG°’) values.
A.
TRUE
B.
FALSE
Question #19
Changing the energy of the reactants or the products is a cellular strategy to increase to spontaneity of a reaction.
A.
FALSE
B.
TRUE
Question #20
Decreasing the concentration of products ensure that a reaction is spontaneous in the forward direction.
A.
TRUE
B.
FALSE
Question #21
Decreasing the concentration of reactants ensure that a reaction is spontaneous in the backwards direction.
A.
TRUE
B.
FALSE
Question #22
The free-energy change depends both on the nature and the initial concentration of reactants and products.
A.
FALSE
B.
TRUE
Question #23
The free energy changes of reactions that have a common intermediate can be multiplied to provide the total free energy change.
A.
TRUE
B.
FALSE
Question #24
The positive value of ΔG°' predicts that, in any conditions, the reaction will tend not to proceed spontaneously in the direction written.
A.
TRUE
B.
FALSE
Question #25
The energy of ATP is
A.
chemical energy
B.
chemical potential energy
C.
atomic energy
D.
thermal energy
Question #26
The hydrolysis of ATP
A.
absorbs energy
B.
releases energy
Question #27
ATP can be stored for long time and then used but the cell to provide chemical energy
A.
TRUE
B.
FALSE
Question #28
ATP contains
A.
3 phosphoanhydride bonds
B.
3 phosphate groups
Question #29
Hydrolysis of the alpha phosphate group release the largest amount of energy
A.
FALSE
B.
TRUE
Question #30
The synthesis of ATP from ADP and Pi is an endergonic reaction.
A.
TRUE
B.
FALSE
Question #31
The free energy necessary for the synthesis of ATP is provided when carbon containing molecules undergo exergonic reactions such as oxidation reactions.
A.
TRUE
B.
FALSE
Question #32
The hydrolysis of one mole GTP provides 30 kJ in standard conditions.
A.
FALSE
B.
TRUE
Question #33
Pyrophosphate contains
A.
one phosphate
B.
four phosphates
C.
two phosphates
D.
three phosphates
Question #34
The products of hydrolysis of ATP are more unstable that ATP
A.
TRUE
B.
FALSE
Question #35
The repulsion between the four negative charges of the phosphate groups is greater in the reactants of the hydrolysis reaction of ATP.
A.
TRUE
B.
FALSE
Question #36
The orthophosphate ion is stabilized by resonance.
A.
TRUE
B.
FALSE
Question #37
The transfer of a phosphoryl group to a compound puts free energy into that compound, making it more stable.
A.
TRUE
B.
FALSE
Question #38
Phosphorylation usually occurs when the phosphorous of the phosphoryl group reacts with an electrophile, such a the oxygen of an hydroxyl group of an alcohol.
A.
TRUE
B.
FALSE
Question #39
Phosphorylation reactions are catalyzed by kinases.
A.
TRUE
B.
FALSE
Question #40
Magnesium is a coenzyme.
A.
TRUE
B.
FALSE
Question #41
The binding of magnesium to ATP makes the hydrolysis reaction more exergonic.
A.
TRUE
B.
FALSE
Question #42
Inorganic polyphosphate is store in the cytosol.
A.
TRUE
B.
FALSE
Question #43
ATP has the highest phosphoryl-transfer potential among phosphoryl containing molecules.
A.
TRUE
B.
FALSE
Question #44
The formation of ATP (or GTP) by the direct transfer of a phosphoryl group to ADP (or GDP) is called substrate level phosphatase.
A.
FALSE
B.
TRUE
Question #45
A phosphorylated compound is considered a high energy compound.
A.
FALSE
B.
TRUE
Question #46
The breakdown of a “super-high-energy compound”, can release the energy necessary for the synthesis of ATP from ADP and Pi.
A.
TRUE
B.
FALSE
Question #47
In the cell, ATP carries 4 positive charges.
A.
FALSE
B.
TRUE
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