The second law of thermodynamics essentially says A) heat is energy B) motion energy converts to heat energy C) at the atomic level, motion is continuous D) entropy increases
The energy required to destabilize existing chemical bonds is called ____ energy. A) activation B) destabilization C) kinetic D) free
If DG is said to be positive, it means A) H is lower B) reactants contain more energy than the product does C) S in the system is higher D) products of the reaction contain more energy than the reactants
Which of the following is uncharacteristic of ATP? A) It is formed by attaching a phosphate group to ADP with a high-energy bond. B) In most reactions involving ATP, only the outer, high-energy bond is hydrolized. C) It is a good long-term energy storage molecule. D) When dephosphorylated, ATP becomes ADP.
The most primitive form of metabolism is A) glycolysis B) oxygen-forming photosynthesis C) the degradation of organic molecules with the released energy stored in ATP D) anaerobic respiration
The First Law of Thermodynamics states that energy can be A) created B) destroyed C) converted D) all of the above E) none of the above
The universal energy currency for all cells is A) ATP B) NAD + C) ADP D) enzymes E) O 2
Enzymes A) make endergonic reactions proceed spontaneously B) lower the activation energy of a reaction C) are not very specific in their choice of substrates D) are needed in large quantities because they are used up during catalysis E) none of the above
To what category of macromolecules do most enzymes belong? A) carbohydrates B) lipids C) steroids D) nucleic acids E) proteins
NAD + is a(n) A) enzyme B) coenzyme C) active site D) high-energy bond E) allosteric activator
Which of the following is a reduced compound? A) CO 2 B) O 2 C) N 2 D) NAD + E) NADH
In an endergonic reaction, A) the reactants contain less free energy than the products B) the reactants contain more free energy than the products C) no activation energy is required D) catalysis cannot occur E) substrates outnumber enzymes
The energy of random molecular motion is called A) heat B) free energy C) enthalpy D) potential energy E) activation energy
The energy available to do work in a system is called A) entropy B) activation energy C) thermodynamics D) free energy E) heat
The initial steps in breaking down glucose are called A) nitrogen fixation B) glycolysis C) chemiosmosis D) intramolecular catalysis E) intermolecular catalysis
A catalyst will make a reaction A) stop B) slow down C) speed up D) go in a different direction E) you can never tell
When molecules are reduced they gain A) energy B) electrons C) hydrogen protons D) all of the above E) none of the above
Which of the following statements about enzymes is true? A) some substrates can make enzymes change shape slightly B) all enzymes have the same pH optimum C) the active sites of all enzymes have the same three-dimensional shape D) all of the above E) none of the above
Cofactors A) break hydrogen bonds in proteins B) help facilitate enzyme activity C) increase activation energy D) are very rare in living organisms E) are linked to ATP by high-energy bonds
How much energy is released when one of the high-energy bonds in ATP is broken? A) 730 cal/mole B) 7.3 cal/mole C) 7.3 kcal/mole D) 73 kcal/mole E) 730 kcal/mole
Consider the hypothetical biochemical pathway H -- I -- J-- K-- L. Which step most likely evolved first? A) H -- I B) I -- J C) I -- H D) J -- K E) K -- L
Why do drastic changes in the temperature or pH of a system alter enzyme activity? A) they change the three-dimensional shape of the enzyme B) they disrupt hydrogen and ionic bonds in the enzyme C) they disrupt hydrophobic interactions in the enzyme D) all of the above E) none of the above
The loss of an electron by a molecule is called A) oxidation B) reduction C) induced fit D) enthalpy E) allosteric inhibition
In the chemical equation G = H - TS, the term G stands for A) entropy B) the reactants C) enthalpy D) free energy E) the products
Enzyme B requires Zn 2+ in order to catalyze the conversion of substrate X. The zinc is best identified as a(n): A) coenzyme B) cofactor C) substrate D) product E) enzyme
The next two questions refer to the following chemical reaction that is catalyzed by the enzyme malic dehydrogenase: malic acid + NAD + -----> oxaloacetic acid + NADH + H + delta G = +7.1 kcal.
Which of the following statements are true of this reaction?
A) Malic acid is reduced to oxaloacetic acid. B) b. The bonds within the products are more stable than those within the substrates. C) The reaction is endergonic. D) Entropy is increasing. E) Both b and c, but not a and d.
NAD + A) is being reduced. B) is a coenzyme. C) is an oxidizing agent. D) all of the above. E) a and b, but not c.
In the malate dehydrogenase reaction given above, NAD + is a reducing agent. A) True B) False
Which of the following must be true for a reaction to occur spontaneously? A) delta G must be negative B) delta H must be negative C) delta S must be positive D) delta G must be positive E) b, c, and d, but not a
Continuing with question 5, this reaction would occur spontaneously. A) True B) False
Redox reactions (oxidation-reduction) A) do not occur in living systems B) require the presence of oxygen C) involve the loss of electrons termed oxidation D) involve the gaining of energy by an oxidized substance E) both a and b
The actions of an enzyme can be affected by all of the following except A) p/PH B) temperature C) allosteric inhibitors D) availability ATP E) cofactors
Which of the following are mismatched A) anabolic reactions-expend energy B) reduction-gain of an electron C) endergonic reaction-anabolism D) exergonic reaction-catabolism E) activation energy-entropy