Questions with Correct Solutions
2025/2026 Updated.
Hydrolysis vs Synthesis of ATP (Which is favorable?) - Answer Hydrolysis: favorable
1st law of thermodynamics - Answer The total energy of a system is conserved
Biological organisms are ____ systems - Answer Open
-Exchange matter & energy with the environment
Heat given by from a reaction - Answer No reaction is 100% efficient: heat being released
(less energy being associated with the cell) is one factor that makes a reaction less efficient
-Heat can be put to use
-Heat can be lost from biological system into the environment
Internal Energy Equation - Answer ΔE = q + w
A function that keeps track of heat transfer and work expenditure in the system
E in the internal energy equation - Answer E = The internal energy: energy of the entire
system - energy within cell + exchange of energy between cell and environment
q in the internal energy equation - Answer q = heat absorbed by the system (absorbed by
organism/exchanged with the environment)
w in the internal energy equation - Answer w = work done on the system (i.e. muscle
contraction, migration of cells, synthesis of macromolecule, energy required to maintain ion
gradients)
2nd law of thermodynamics - Answer systems tend toward disorder and randomness
(ordered to disordered states)
Ordered states - Answer i.e. maintaining a structure
,Favorable reactions _____ energy and _____ entropy - Answer Release; increase
Exergonic reactions - are they favorable + Comparison of the energy of reactants vs products -
Answer Favorable: energy is released
Energy of reactants > Products
ATP Hydrolysis - what makes it favorable? - Answer 1. Exergonic
2. Increase in entropy (1 reactant --> 2 products)
Unfavorable reactions ______ energy and _____ entropy - Answer absorb; decrease
Endergonic reactions - are they favorable + Comparison of the energy of reactants vs products -
Answer Unfavorable: require an input of energy
Energy of reactants < Products
Examples of endergonic reactions - Answer Synthesis of a peptide bond
Synthesis of ATP
Gibbs free energy (G) - Answer Available energy to do "work"
What is "G" based on? - Answer Differences in chemical bond energy between products &
reactants
Covalent bonds & G - Answer Most energy contained in them
Non-covalent interactions & G - Answer Add up - a lot of energy when there are a lot of
these interactions
Biological systems' problem with the tendency of a reaction to go towards equilibrium - Answer
-Forward & reverse reactions occur together - no net energy to do work
-Therefore, are able to shift a reaction away from equilibrium in order to capture energy for
work
, Free energy equation - Answer ΔG = ΔH - TΔS
A measure of the distance from the equilibrium of a reaction
ΔH in the free energy equation - Answer Enthalpy: overall change in bond energy when
bonds are broken/formed in a reaction
ΔS in the free energy equation - Answer Entropy
T in the free energy equation - Answer All reactions are affected by temperature and
pressure (pressure is kept constant)
keq: definition - Answer Equilibrium constant: The tendency of a reaction to go toward
completion
keq: equation - Answer keq = [C]^c [D]^d / [A]^a [B]^b = [Products]/[Reactants]
keq: range & what large/small values mean - Answer 10^-3 to 10^3
Large keq: near completion - reaction will proceed until conversion is nearly complete
Small keq: far from equilibrium
ΔG^o - Answer free energy change under standard states
What are the standard states in ΔG^o and why are they necessary? - Answer Gases: pressure
of 1 atm
Solutions: concentrations of 1M
Needed when comparing the energy generated from one reaction to another
Relationship between ΔG and ΔG^o - Answer ΔG = ΔG^o + RTln(keq)
R in ΔG equation - Answer 8.31 J/molK