This set of Biochemistry Multiple Choice Questions & Answers (MCQs) focuses on “Bioenergetics and Thermodynamics”.
1. If enthalpy change for a reaction is zero, then ∆G° equals to _____________
Explanation: From the equation, ∆G° = ∆H°-T∆S°
If ∆H° = 0 then ∆G° = -T∆S°.
2. ∆G° is defined as the ____________
a) Residual energy present in the reactants at equilibrium
b) Residual energy present in the products at equilibrium
c) Difference in the residual energy of reactants and products at equilibrium
d) Energy required in converting one mole of reactants to one mole of products
Explanation: ∆G° is defined as the energy required in converting one mole of reactants to one mole of products.
3. For a reaction if ∆G° is positive, then ____________
a) The products will be favored
b) The reactants will be favored
c) The concentration of the reactants and products will be equal
d) All of the reactant will be converted to products
Explanation: If ∆G° is negative, products are favored.
4. Unfolding of regular secondary protein structure causes ____________
a) Large decrease in the entropy of the protein
b) Little increase in the entropy of protein
c) No change in the entropy of the protein
d) Large increase in the entropy of the protein
Explanation: Entropy increases on a larger scale when unfolding of secondary protein structure takes place.
5. The study of energy relationships and conversions in biological systems is called as ____________
Explanation: Bioenergetics is the study of energy relationships and conversions in biological systems.
6. The relationship between K‘eq and ∆G‘° is?
a) ∆G‘° = RTlnK‘eq
b) ∆G‘° = -RTK‘eq
c) ∆G‘° = RK‘eq
d) ∆G‘° = -RK‘eq
Explanation: If the system is in equilibrium ∆G° = 0 and ∆G‘° = -RTK‘eq is the correct relation between K‘eq and ∆G‘°.
7. What does first law of thermodynamics state?
a) Energy can neither be destroyed nor created
b) Energy cannot be 100 percent efficiently transformed from one type to another
c) All living organisms are composed of cells
d) Input of heat energy increases the rate of movement of atoms and molecules
Explanation: First law of thermodynamics can also be termed as law of conservation of energy which states that energy can neither be destroyed nor created but can be transformed from one form of energy to another.
8. If ∆G‘° of the reaction A → B is -40kJ/mol under standard conditions then the reaction ____________
a) Will never reach equilibrium
b) Will not occur spontaneously
c) Will proceed at a rapid rate
d) Will proceed from left to right spontaneously
Explanation: If ∆G‘° < 0, reaction proceeds from left to right that means products are favored.
9. What is the relationship between ∆G and ∆G‘°?
a) ∆G = ∆G‘° + RTln([products]/[reactants])
b) ∆G = ∆G‘° – RTln([products]/[reactants])
c) ∆G = ∆G‘° + RTln([reactants]/[products])
d) ∆G = ∆G‘° – RTln([reactants]/[products])
Explanation: ∆G = ∆G‘° + RTln([products]/[reactants] ) is the correct relation between ∆G and ∆G‘°.
10. Which of the following statements is false?
a) The reaction tends to go in the forward direction if ∆G is large and positive
b) The reaction tends to move in the backward direction if ∆G is large and negative
c) The system is at equilibrium if ∆G = 0
d) The reaction tends to move in the backward direction if ∆G is large and positive
Explanation: The reaction tends to move in the backward direction if ∆G is large and negative.
Sanfoundry Global Education & Learning Series – Biochemistry.
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