bio chapter 8

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bio chapter 8
2012-03-06 23:12:46
an introduction metabolism

biology 1703
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  1. which of the following describes some aspect of metabolism?
    • A) synthesis of macromolecules
    • B) breakdown of macromolecules
    • C) control of enzyme activity
  2. which term most precisely descorbes the cellular process of breaking down large molecules into smaller ones?
  3. which of the follwing statements correctly describes catabolic pathways?
    they release energy as they degrade polymers to monomers
  4. which of the following is (are) true for anabolic pathways?
    • B)they are highly regulated sequences of chemical reactions
    • C) they consume energy to build up polymers from monomers
  5. which of the following is a statement of the first law of thermodynamics?
    energy cannot be created or destroyed
  6. the first law of thermodynamics states that energy can be neither created or destroyed. for living organisms, which of the following is an important consequence of the first law?
    the organism ultimatley must obtain alll of the necessary energy for life from its environment
  7. according to the first law of thermodynamics,
    energy can be niether created or destroyed
  8. living organisms increase in complexity as they grow, resulting in a decrease in the entrophy of an organism. How does this relate to the 2nd law of thermodynamics?
    as a consequence of growing, organisms create more disorder in their environment than the decrease in entrophy associated with their growth.
  9. which of the following statements about metabolism is incorrect?
    metabolism is an emergent property of life at the level of organisms
  10. whenever energy is transformed, there is always an increase in the ?
    entrophy of the universe
  11. Which of the following statements is a logical consequence of the second law of thermodynamics?
    Every chemical reaction must increase the total entropy of the universe.
  12. Which of the following statements correctly describe(s) some aspect of energy in living organisms?
    • A) Living organisms can convert energy among several different forms.
    • B) Living organisms can use energy to do work.
    • C) Organisms expend energy in order to decrease their entropy
  13. Which of the following statements isnot representative of the second law of thermodynamics?
    Every energy transformation by a cell decreases the entropy of the universe.
  14. Which of the following forms of energy is least available to accomplish cellular work?
    thermal energy (heat)
  15. Which of the following types of reactions would decrease the entropy within a cell?
    dehydration reactions
  16. According to the second law of thermodynamics, which of the following statements isincorrect?
    The synthesis of large molecules from small molecules is exergonic.
  17. The organization of organisms has become increasingly complex with time. This statement
    is consistent with the second law of thermodynamics.
  18. The mathematical expression for the change in free energy of a system is: ΔG= ΔH–TΔS. Which of the following is (are)incorrect?
    ΔH is the change in enthalpy, the energy available to do work.
  19. What is the change in free energy of a system at chemical equilibrium?
    no net change
  20. Which of the following istrue for all exergonic reactions?
    The reaction proceeds with a net release of free energy.
  21. Chemical equilibrium is relatively rare in living cells. Which of the followingcouldbe an example of a reaction at chemical equilibrium in a cell?
    a chemical reaction in which both the reactants and products are only used in a metabolic pathway that is completely inactive
  22. Which of the following shows the correct changes in thermodynamic properties for a chemical reaction in which amino acids are linked to form a protein?
    +ΔH, -ΔS, +ΔG
  23. When glucose monomers are joined together by glycosidic linkages to form a cellulose polymer, the changes in free energy, total energy, and entropy are as follows:
    B) +ΔG, +ΔH, -ΔS
  24. A chemical reaction that has a positive ΔG is correctly described as
  25. why is ATP an important molecule in metabolism?
    it provides energy couplinh between exergonic and endergonic reactions
  26. The hydrolysis of ATP to ADP and inorganic phosphate (ATP + H2O → ADP + Pi )
    • A) has a ΔGof about -7 kcal/mol under standard conditions.
    • B) involves hydrolysis of a terminal phosphate bond of ATP.
    • C) can occur spontaneously under appropriate conditions.
  27. When 10,000 molecules of ATP are hydrolyzed to ADP and Pi in a test tube, about twice 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?
    Cells convert some of the energy of ATP hydrolysis into other forms of energy besides heat.
  28. ATP generally energizes a cellular process by
    coupling free energy released by ATP hydrolysis to free energy needed by other reactions.
  29. Which of the following reactions is most likely to be coupled to the reaction ATP + H2O →ADP + Pi (ΔG = -7.3 kcal/mol)?
    E + Pi →EP (ΔG = +5 kcal/mol)
  30. Which of the following is most similar in structure to ATP?
    RNA nucleotides
  31. What term is used to describe the transfer of free energy from catabolic pathways to anabolic pathways?
    energy coupling
  32. Which of the following statements istrue concerning catabolic pathways?
    They are usually coupled with anabolic pathways to which they supply energy in the form of ATP.
  33. Which of the following statements regarding ATP is (are) correct?
    • A) ATP serves as a main energy shuttle inside cells.
    • B) ATP drives endergonic reactions in the cell by the enzymatic transfer of the phosphate group to specific reactants.
    • C) The regeneration of ATP from ADP and phosphate is an endergonic reaction.
  34. Which of the following statements is (are)trueabout enzyme-catalyzed reactions?
    The reaction is faster than the same reaction in the absence of the enzyme.
  35. How can one increase the rate of a chemical reaction?
    Add a catalyst.
  36. Sucrose is a disaccharide, composed of the monosaccharides glucose and fructose. The hydrolysis of sucrose by the enzyme sucrase results in
    C) breaking the bond between glucose and fructose and forming new bonds from the atoms of water.
  37. 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.
  38. A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because
    C) the activation energy barrier for this reaction cannot be surmounted.
  39. Which of the following statements regarding enzymes istrue?
    B) Enzymes increase the rate of a reaction.
  40. Which of the following isnottrue of enzymes?
    C) Enzymes provide activation energy for the reaction they catalyze.
  41. An enzyme catalyzes a reaction by
    lowering the energy of activation of a reaction.
  42. Which of these statements regarding enzymes isfalse?
    Enzymes provide activation energy for the reactions they catalyze.
  43. During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a ΔGof -20 kcal/ mol. If you double the amount of enzyme in the reaction, what will be the ΔG for the new reaction?
    -20 kcal/mol
  44. The active site of an enzyme is the region that
    B) is involved in the catalytic reaction of the enzyme.
  45. According to the induced fit hypothesis of enzyme catalysis, which of the following isCORRECT?
    The binding of the substrate changes the shape of the enzyme's active site.
  46. Many different things can alter enzyme activity. Which of the following underlie all types of enzyme regulation?
    • A) changes in the activation energy of the reaction
    • B) changes in the active site of the enzyme
  47. As temperature decreases, the rate of an enzyme-catalyzed reaction also decreases. Which of the following explain(s) why this occurs?
    • A) Fewer substrates have sufficient energy to get over the activation energy barrier.
    • B) Motion in the active site of the enzyme is slowed, thus slowing the catalysis of the enzyme.
  48. ATP is often an allosteric inhibitor of key enzymes in catabolic pathways. Which of the following statements isinconsistentwith the role of ATP?
    D) Increasing availability of ATP increases the energy available to drive endergonic reactions.
  49. Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?
    C) competitive inhibition
  50. What is a nonprotein "helper" of an enzyme molecule called?
  51. Which of the following is true of enzymes?
    E) All of the above are true of enzymes.
  52. Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as a(n)
    D) cofactor necessary for enzyme activity.
  53. Consider the following: Succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic acid. Which of the following is correct?
    C) Succinate is the substrate, and fumarate is the product.
  54. Assume that the reaction has aΔGof -5.6 kcal/mol. Which of the following would be true?
    D) The reaction would result in an increase in entropy (S) and a decrease in the total energy content (H) of the system.
  55. The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is known as
    feedback inhibition.
  56. The regulation of enzyme function is an important aspect of cell metabolism. Which of the following is least likelyto be a mechanism for enzyme regulation?
    ) removing cofactors
  57. Which of the following statements istrueregarding enzyme cooperativity?
    C) A substrate molecule bound to an active site affects the active site of several subunits.
  58. How does a non-competitive inhibitor decrease the rate of an enzyme reaction?
    B) by changing the structure of the enzyme
  59. 72) Which of the following statements correctly indicate(s) the role of ATP or ADP as an allosteric regulator? Assume that the supply of energy for cellular processes is adjusted to meet cellular demand for energy.
    • A) ATP is an allosteric inhibitor of catabolic pathways.
    • B) ADP is an allosteric activator of catabolic pathways.
    • C) ATP is an allosteric activator of anabolic pathways.
  60. An increase in the level of cellular ATP is likely to occur under which of the following conditions?
    • ) increased activity of catabolic pathways
    • B) decreased activity of anabolic pathways
    • C) allosteric inhibition of anabolic pathways
  61. In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP?
    B) cellular respiration
  62. What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?
  63. In the reaction A → B + C + heat,
    the potential energy of the products is less than that of the reactant.
  64. 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.
  65. What name is given to the reactants in an enzymatically catalyzed reaction?
  66. Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as ________ is to ________.
    exergonic; endergonic
  67. Most cells cannot harness heat to perform work because
    temperature is usually uniform throughout a cell.
  68. According to the first law of thermodynamics,
    energy is conserved in all processes.
  69. Which of the following metabolic processes can occur without a net influx of energy from some other process?
    C6H12O6+ 6 O2→ 6 CO2+ 6 H2O
  70. If an enzyme has been inhibited noncompetitively,
    the inhibitor molecule may be chemically unrelated to the substrate.
  71. If an enzyme solution is saturated with substrate, the most effective way to obtain an even faster yield of products is to
    ) add more of the enzyme.
  72. If an enzyme is added to a solution where its substrates and products are in equilibrium, what would occur?
    Nothing; the reaction would stay at equilibrium.
  73. Some bacteria are metabolically active in hot springs because
    their enzymes have high optimal temperatures.
  74. Which of the following characteristics is not associated with allosteric regulation of an enzyme's activity?
    A mimic of the substrate competes for the active site.