hw 4

The chemical energy stored in ATP is converted to mechanical energy that moves organelles around within the cell. This is an example of __________. A. energy transduction B. being exothermic C. polymerization D. being exergonic

A. energy transduction

Exothermic reactions _________. A. release heat to the surroundings. B. are always spontaneous and lose free energy to the surroundings. C. are always spontaneous. D. lose free energy to the surroundings.

A. release heat to the surroundings.

Enzymes act by: A. increasing activation energy. B. decreasing activation energy. C. lowering the overall free energy change of a reaction. D. decreasing the distance reactants must diffuse to find each other.

B. decreasing activation energy.

The free-energy change of a reaction is determined by the: A. intrinsic properties of reactants and products. B. concentrations of reactants and products. C. temperature of reactants and products. D. All of the above

D. all of the above

A metabolic pathway must provide the desired chemical (metabolite) at the rate required for cellular and tissue function. To accomplish this, the reaction sequence ________. A. "couples" energetically unfavorable reactions to ATP hydrolysis in order to drive the reaction toward the required product. B. includes only chemical reactions that are energetically favorable under the conditions for which synthesis is required. C. includes only reactions that are essentially irreversible. D. all of the choices are correct

A. "couples" energetically unfavorable reactions to ATP hydrolysis in order to drive the reaction toward the required product.

An enzyme inhibitor is a molecule that is able to ______ an enzyme and _____ its activity. A. activate; increase B. bind to; decrease C. activate; decrease D. bind to; increase

B. bind to; decrease

The hydrolysis of ATP to ADP and phosphate allows glucose-6-phosphate to be synthesized from glucose and phosphate because the: A. heat produced from ATP hydrolysis drives glucose-6-phosphate synthesis. B. enzymatic coupling of these two reactions allows the energy of ATP hydrolysis to drive the synthesis of glucose-6-phosphate. C. energy of glucose phosphorylation drives ATP splitting. D. All of the above

B. enzymatic coupling of these two reactions allows the energy of ATP hydrolysis to drive the synthesis of glucose-6-phosphate.

Enzymes have the advantage that they can be regulated. One major way in which this is done is the addition of _______ groups, which can activate or deactivate an enzyme. A. carbohydrate B. phosphate C. sulfyhdryl D. amino

B. phosphate

When a chemical reaction is at equilibrium, which of the following statements is always TRUE? A. The equilibrium constant (Keq) equals 1. B. All of the choices are correct. C. The rate of the forward reaction is equal to the rate of the backward reaction. D. The ratio of the concentrations of reactants and products equals 1.

C. The rate of the forward reaction is equal to the rate of the backward reaction.

Reactions that gain heat from the surroundings are said to be __________ A. able to occur spontaneously. B. endergonic. C. endothermic. D. exothermic.

C. endothermic.

The effect of a competitive inhibitor can be reversed by _______. A. massaging the enzyme B. increasing inhibitor concentration C. increasing substrate concentration D. changing the pH E. heating the reaction mixture

C. increasing substrate concentration

What kind of enzyme adds phosphate groups to enzymes for the purpose of activating or deactivating them? A. carboxypeptidase B. flippases C. protein kinases D. glycosyltransferases E. phosphatases

C. protein kinases

Coenzymes are: A. proteins that form dimeric enzymes. B. enzymes in the same pathway. C. small molecules that work with an enzyme to enhance reaction rate. D. small molecules that allosterically regulate enzymes.

C. small molecules that work with an enzyme to enhance reaction rate.

What are the energetic consequences of coupling a reaction with a + ΔG to one with a larger - ΔG? A. An outcome in which the overall ΔG is positive B. An outcome in which the overall ΔG is unfavorable C. An outcome in which both reactions are energetically unfavorable overall D. A ΔG that is favorable overall and drives the reaction with a +ΔG in the forward direction

D. A ΔG that is favorable overall and drives the reaction with a + ΔG in the forward direction

Enzymes affect the transition state of a chemical reaction by: A. binding to substrate(s). B. providing a surface on which reactions converting substrate to product can occur more rapidly. C. altering the conformation of substrate(s) to approach that of the transition state. D. All of the above

D. All of the above

Significant features of the coupling of an endergonic and an exergonic reaction is that ________. A. the two reactions have a common intermediate. B. none of the choices are correct. C. the hydrolysis of ATP can be used to drive the overall reaction. D. All of the choices are correct. E. the value of a positive ΔG for one of the reactions can be overcome.

D. All of the choices are correct.

Like other catalysts, enzymes: A. increase the rate of reactions without being consumed in reactions. B. shift the chemical equilibrium from more reactants to more products. C. do not alter the chemical equilibrium between reactants and products. D. Both a and c

D. Both a and c

Entropy is associated with the _______ movement of particles of matter, which because they are _____ CANNOT accomplish a directed work process. A. slow, rapid B. rapid, random C. rapid, directed D. random, random

D. random, random

What kind of organism reaches equilibrium? A. a eukaryote B. one with a low metabolic rate C. a prokaryote D. one that is actively metabolizing E. a dead organism

E. a dead organism

A reaction involving the gain of one or more electrons is a(n) __________ reaction. A. oxidation B. none of the choices is correct C. elimination D. inclusion E. reduction

E. reduction

The concept that events in the universe have direction and that they tend to proceed from a state of higher energy to a state of lower energy is known as _________. As a result, in any energy transformation, there is a decreasing availability of energy for doing additional work. A. the law of entropy B. the first law of thermodynamics C. the second law of thermodynamics D. the Beer-Lambert Law

the second law of thermodynamics