Mastering Biology: 8.2/8.3 Review

The mathematical expression for the change in free energy of a system is ∆G=∆H-T∆S. Which of the following is (are) correct?

∆G is the change in free energy

A system at chemical equilibrium__________.

can do no work

Which of the following is true for all exergonic reactions?

The reaction proceeds with a net release of free energy

A chemical reaction that has a ∆G is best described as_______.

endergonic

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

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

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as ________ is to__________.

exergonic; endergonic

In solution, why do hydrolysis reactions occur more readily than condensation reactions?

Hydrolysis increases entropy and is exergonic

The following reaction

A---->B+C+ heat is a(n)____________ reaction.

exergonic (energy has been released)

A(n) ______________ reaction occurs spontaneously.

exergonic

Which of these reactions requires a net input of energy from its surroundings?

endergonic

In cells, what is usually the immediate source of energy for an endergonic reaction?

ATP

The reaction ADP+P----> ATP is a(n) ___________ reaction.

endergonic

The energy for an endergonic reaction comes from a(n) ___________ reaction.

exergonic

What is the fate of the phosphate group that is removed when ATP is converted to ADP?

it is acquired by a reactant in an endergonic reaction

Select the INCORRECT association.

exergonic. . . . .uphill

What is energy coupling?

the use of energy released from an exergonic reaction to drive an endergonic reaction

Why is ATP an important molecule in metabolism?

It provides energy coupling between exergonic and endergonic reactions.

When 10,000 molecules of ATP are hydrolyzed to ADP and Pi in a test tube, about half as much heat is liberated as when a cell hydrolyzes the same amount of ATP. Which of the following is the best explanation for this observation?

Reactant and product concentrations in the test tube are different from those in the cell.

Which of the following is most similar in structure to ATP?

an RNA molecule

Catabolic pathways_______________.

Supply energy, primarily in the form of ATP, for the cell's work.

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

It is lost to the environment

When ATP releases some energy, it also releases inorganic phosphate. What happens to the inorganic phosphate in the cell?

It may be used to form a phosphorylated intermediate

Which of the following is the most correct interpretation of this figure? (ATP cycle)

ATP is a molecule that acts as an intermediary to store energy for cellular work.

How do cells use the ATP cycle shown in the figure?

Cells use the cycle to recycle ADP and phosphate.

A number of systems for pumping ions across membranes are powered by ATP. Such ATP-powered pumps are often called ATPases.. . . . . . . .

ATPase activity must be pumping calcium from the cytosol to the SR against the concentration gradient.