Lecture 2

Question 1

Which of the following involves a decrease in entropy?

a. depolymerization reactions
b. reactions that separate monomers
c. condensation reactions
d. hydrolysis reactions

Answer 1

c. condensation reactions

Question 2

For living organisms, which of the following is an important consequence of the first law of thermodynamics?

a. The entropy of an organism decreases with time as the organism grows in complexity
b. The energy content of an organism is constant
c. Organisms grow by converting energy into organic matter
d. The organism ultimately must obtain all of the necessary energy for life from its environment

Answer 2

d. The organism ultimately must obtain all of the necessary energy for life from its environment

Question 3

Which of the following statements is representative of the second law of thermodynamics?

a. Every energy transformation by a cell decreases the entropy of the universe.
b. Without an input of energy, organisms would tend toward decreasing entropy.
c. Cells require a constant input of energy to maintain their high level of organization.
d. Conversion of energy from one form to another is always accompanied by some gain of free energy.

Answer 3

c. Cells require a constant input of energy to maintain their high level of organization.

Question 4

Which of the following statements about equilibrium of chemical reactions is correct?

a. The equilibrium point of a reaction represents the least stable configuration for that reaction.
b. Most reactions in a living cell are close to equilibrium.
c. Reactions can only go in the direction toward equilibrium.
d. The equilibrium point is where the system has the highest free energy.
e. A reaction that is at equilibrium is not capable of doing any work.

Answer 4

e. A reaction that is at equilibrium is not capable of doing any work.

Question 5

When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?

a. It is used to generate ADP from nucleotide precursors.
b. It is used to power yet more cellular work.
c. It is lost to the environment.
d. It is used to store energy as more ATP.

Answer 5

c. It is lost to the environment.

Question 6

A chemical reaction that has a positive (delta)G is best described as \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_.
 a. endergonic
 b. enthalpic
 c. spontaneous
 d. exergonic	
(See lecture 2 question 8 figure)

Answer 6

a. endergonic

Question 7

Chemical equilibrium is relatively rare in living cells. An example of a reaction at chemical equilibrium in a cell would be _____.

a. an endergonic reaction in an active metabolic pathway where the energy for that reaction is supplied only by heat from the environment
b. one in which the entropy change in the reaction is just balanced by an opposite entropy change in the cell’s surroundings
c. one in which the free energy at equilibrium is higher than the energy content at any point away from equilibrium
d. a chemical reaction in which both the reactants and products are not being produced or used in any active metabolic pathway at that time in the cell

Answer 7

d. a chemical reaction in which both the reactants and products are not being produced or used in any active metabolic pathway at that time in the cell