Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as ___ is to ___.
A) exergonic; endergonic
Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?
D) catabolism (catabolic pathways)
Biological systems use free energy based on empirical data that all organisms require a constant energy input. The first law of thermodynamics states that energy can be neither created nor destroyed. For living organisms, which of the following statements is an important consequence of this first law?
D) The organism must ultimately obtain all the necessary energy for life from its environment.
Which of the following types of reactions would decrease the entropy within a cell?
C) Anabolic reactions
Biological evolution of life on Earth, from simple prokaryote-like cells to large, multicellular eukaryotic organisms, ___.
D) has occured in accordance with the laws of thermodynamis
Which of the following statements is representative of the second law of thermodynamics?
C) Cells require a constant input of energy to maintain their high level of organization
A system at chemical equilibrium __.
C) can do no work
A chemical reaction that has a positive ΔG is best described as __.
B) endergonic
When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?
D) It is lost to the environment
The mathematical expression for the change in free energy of a system is ΔG = ΔH - TΔS. Which of the following is (are) correct?
C) ΔG is the change in free energy
How do cells use the ATP cycle?
D) Cells use the cycle to recycle ADP and phosphate
The conversion of A into B has a ΔG of +13 kcal/mol, and the conversion of C into D has a ΔG of -25 kcal/mol. If the two reactions are coupled through an enzyme, such that A+C goes to B+D, what is the free energy change, and in which direction will the reaction proceed?
B) ΔG = -12 kcal/mol; forward direction
A reaction that has ΔG of +1.9 kcal/mol would not occur spontaneously, but could occur spontaneously when couple to the hydrolysis of ATP. If the hydrolysis of one molecule of ATP to ADP + Pi has ΔG of -7.3 kcal/mol, hydrolysis of how many molecules of ATP would need to be couple to this reaction for it to occur spontaneously?
D) 1 molecules of ATP
Which of the following is most similar in structure to ATP?
C) An RNA nucleotide
Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely function as __.
D) a cofactor necessary for enzyme activity
According to the induced fit hypothesis of enzyme catalysis, __.
C) the binding of the substrate changes the shape of the enzyme's active site
Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's __.
B) activation energy
You have discovered an enzyme that can catalyze two different chemical reactions. Which of the following is most likely to be correct?
B) Either the enzyme has two distinct active sites or the reactants involved in the two reactions are very similar in size and shape
The active site of an enzyme is the region that __.
C) is involved in the catalytic reaction of the enzyme
The oxidation of glucose to CO2 and H2O is highly exergonic: ΔG of -7.3 kcal/mol. This is spontaneous, but why is it very slow?
D) Few glucose and oxygen molecules have the activation energy at room temperature
Which of the following is true of metabolism in its entirety in all organisms?
D) Metabolism consists of all energy transformation reactions in an organism
Which of the following is an example of potential rather than kinetic energy?
A) A molecule of glucose
For living organisms, which of the following is an important consequence of the first law of thermodynamics?
B) The organism ultimately must obtain all of the necessary energy for life from its environment
Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics?
D) As a consequence of growing, organisms cause a greater increase in entropy in their environment than the decrease in entropy associated with their growth
Which of the following is true for all exergonic reactions?
D) The reaction proceeds with a net release of free energy
In solution, why do hydrolysis reactions occur more readily than condensation reactions?
B) Hydrolysis increases entropy and is exergonic
The breakdown of food molecules in the gut does not require coupling of ATP hydrolysis, but enzymes are required to speed up these spontaneous reactions.
True or False
True
They hydrolysis of ATP has ΔG of -7.3 kcal/mol. If it takes 2.1 kcal/mol of energy to move one Na+ ion across the membrane (ΔG = +2.1 kcal/mol), how many sodium ions could be moved by the hydrolysis of one ATP molecule?
C) 3 Na+ ions
Allosteric enzyme regulation is usually associated with __.
A) an enzyme with more than one subunit
Besides turning enzymes on or off, what other means does a cell use to control enzymatic activity?
A) Localization of enzymes into specific organelles or membranes
Which of the following is true when comparing an uncatalyzed reaction to the same reaction with a catalyst?
B) The catalyzed reaction will have the same G
When ATP releases some energy, it also releases inorganic phosphate. What happens to the inorganic phosphate in the cell?
B) It may be used to form a phosphorylated intermediate
Which of the following is true of enzymes?
C) Enzymes increase the rate of chemical reaction by lowering activation energy barriers
Protein kinases are enzymes that transfer the terminal phosphate from ATP to an amino acid residue on the target protein. Many are located on the plasman membrane as integral membrane proteins or peripheral membrane proteins. What purpose may be served by their plasma membrane localization?
D) They can more readily encounter and phosphorylate other membrane proteins
