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WorksheetsBioenergetics & Thermodynamics
Total questions: 24
Worksheet time: 27mins
A reaction that is exergonic will be spontaneous. True or False?
(a)
An endergonic reaction requires an input of energy to proceed. True or False?
(a)
By definition, a spontaneous reaction is one in which
energy is released
energy is absorbed
the energy change is zero
the reaction is fast
the reaction is slow
Reactions that are thermodynamically unfavourable (energy consuming reactions) can occur in living cells because they can be coupled with reaction which have a negative ΔG . True or False?
true
false
Which statement about ΔG is correct?
a positive or negative ΔG tells us which direction the reaction will proceed
ΔG depends on the concentration of reactants and products
ΔG is affected by temperature
ΔG is affected by pressure and pH
ΔG is negative for endergonic reactions
Which equation defines a system at equilibrium?
ΔG > 0
ΔG° = ΔG
ΔG = 0
ΔG = RT ln ([products]/[reactants])
Consider these reactions:
ATP → ADP + Pi ΔG°' = −31 kJ/mol
glucose-6-phosphate → glucose + Pi ΔG°' = −13 kJ/mol
glucose + ATP → glucose-6-phosphate + ADP ΔG°' = ?
What is the ΔG°' of the last reaction?
-44 kJ/mol
-18 kJ/mol
+18 kJ/mol
+44 kJ/mol
If the ∆G°' of the reaction A → B is -40 kJ/mol, under standard conditions the reaction ________
is at equilibrium
will never reach equilibrium
will not occur spontaneously
will proceed at a rapid rate
will proceed spontaneously from left to right
The reaction A + B → C has a ΔG0' of –20 kJ/mol at 25 °C.
Starting under standard conditions, one can predict that ________
at equilibrium, the concentration of B will exceed the concentration of A
at equilibrium, the concentration of C will be less than the concentration of A
at equilibrium, the concentration of C will be much greater than the concentration of A or B
C will rapidly break down to A + B
when A and B are mixed, the reaction will proceed rapidly toward formation of C
A chemical reaction is faster when
∆G > 0
∆G < 0
the activation energy is high
the activation energy is low
Oxidation refers to the
loss of oxygen
gain of oxygen
loss of electrons
gain of electrons
An oxidising agent
loses oxygen
gains oxygen
loses electrons
gains electrons
Biological oxidation-reduction reactions always involve ________
transfer of electron(s)
direct participation of oxygen
mitochondria
formation of water
transfer of hydrogens
In biological redox reactions, hydrogen ions are usually transferred along with electrons. True or false
true
false
Standard reduction potential (E°) is measured in Volts in standard conditions, and relates with the affinity for electrons of an electron acceptor. True or False?
true
false
Which of the following is not true about enzymes:
they increase ∆G of reactions
they are usually made of amino acids
they lower the activation energy of chemical reactions
each one is specific to the particular substrate(s) to which it binds
Which of the following senetences about endergonic and exergonic reactions is false?
endergonic reactions have a positive ΔG and exergonic reactions have a negative ΔG
endergonic reactions consume energy and exergonic reactions release energy
both endergonic and exergonic reactions require energy to overcome an activation barrier
endergonic reactions take place slowly and exergonic reactions take place quickly
Which of the following is the best way to judge the relative activation energies between two given chemical reactions?
compare the ΔG values between the two reactions
compare their reaction rates
compare their ideal environmental conditions
compare the spontaneity between the two reactions
Which of the following is not true about enzymes:
they increase ΔG of reactions
they are usually made of amino acids
they lower the activation energy of chemical reactions
each one is specific to the substate(s) to which it binds
If the ΔG′0 of the reaction A → B is 40 kJ/mol, under standard conditions the reaction:
is at equilibrium
will proceed spontaneously from left to right
will proceed spontaneously from right to left
will never reach equilibrium
will proceed at a rapid rate
For the reaction A → B, ΔG′0 = – 60 kJ/mol.
The reaction is started with 10 mmol of A; no B is initially present.
After 24 hours, analysis reveals the presence of 8 mmol of A and 2 mmol of B. Which option is the most likely explanation?
A and B have reached equilibrium concentrations
an enzyme has shifted the equilibrium toward A
the formation of B is kinetically slow; equilibrium has not been reached by 24 hours
formation of B is thermodynamically unfavourable
the result described is impossible, given the fact that ΔG'0 is -60 kJ/mol
Which of the following compounds releases the most free energy on hydrolysis?
phosphoenolpyruvate – 61.9 kJ/mol
1,3-bisphosphoglycerate – 49.4 kJ/mol
ATP (→ AMP) – 45.6 kJ/mol
Phosphocreatine – 43.1 kJ/mol
GTP (→ GDP) – 30.5 kJ/mol
phosphoenolpyruvate
1,3-bisphosphoglycerate
ATP (→ AMP)
Phosphocreatine
GTP (→ GDP)
Biological oxidation-reduction reactions always involve ________
transfer of election(s)
direct participation of oxygen
mitochondria
formation of water
transfer of hydrogens
Bioenergetics studies energy transformations. Muscle contractions involve the conversation of
chemical energy to kinetic energy
chemical energy to potential energy
kinetic energy to chemical energy
potential energy to chemical energy
potential energy to kinetic energy
