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Bio 2 Test

28 Questions
Science Quizzes & Trivia

Chapters 5-8

Questions and Answers
  • 1. 
    How do cells use the ATP cycle shown in the figure?
    • A. 

      Cells use the cycle to recycle ADP and phosphate

    • B. 

      Cells use the cycle to recycle energy released by ATP hydrolysis

    • C. 

      Cells use the cycle to recycle ADP, phosphate, and the energy released by ATP hydrolysis

    • D. 

      Cells us the cycle primarily to generate heat.

  • 2. 
    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 reduces the inhibitory effect of malonic acid. Based on this information, which of the following is correct?
    • A. 

      Succinate dehydrogenase is the enzyme, and fumarate is the substrate

    • B. 

      Succinate dehydrogenase is the enzyme, and malonic acid is the substrate

    • C. 

      Succinate is the substrate, and fumarate is the product

    • D. 

      Fumarate is the product, and malonic acid is a noncompetitive inhibitor

    • E. 

      Malonic acid is the product, and fumarate is a competitive inhibitor

  • 3. 
    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 reduces the inhibitory effect of malonic acid. What is malonic acid's role with respect to succinate dehydrogenase?
    • A. 

      It is a competitive inhibitor.

    • B. 

      It blocks the binding of fumarate

    • C. 

      It is a noncompetitive inhibitor

    • D. 

      It is able to bind to succinate

    • E. 

      It is an allosteric regulator

  • 4. 
    A series of enzymes catalyze the reaction X->Y->Z->A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. What is substance X?
    • A. 

      A coenzyme

    • B. 

      An allosteric inhibitor

    • C. 

      A substrate

    • D. 

      An intermediate

    • E. 

      The product

  • 5. 
    A series of enzymes catalyze the reaction X->Y->Z->A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. With respect to the enzyme that converts X to Y, substance A functions as?
    • A. 

      A coenzyme

    • B. 

      An allosteric inhibitor

    • C. 

      A substrate

    • D. 

      An intermediate

    • E. 

      A competitive inhibitor

  • 6. 
    Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as __________ is to __________.
    • A. 

      Exergonic; spontaneuos

    • B. 

      Exergonic; endergonic

    • C. 

      Free energy; entropy

    • D. 

      Work; energy

    • E. 

      Entryopy; enthalpy

  • 7. 
    Most cells cannot harness heat to perform work because
    • A. 

      Heat is not a form of energy

    • B. 

      Cells do not have much heat; they are relatively cool

    • C. 

      Temperature is usually uniform throughout a cell

    • D. 

      Heat can never be used to do work

    • E. 

      Heat must remain constant during work.

  • 8. 
    Which of the following metabolic processes can occur without a net influx of energy from some other process?
    • A. 

      ADP+Pi -> ATP + H20

    • B. 

      C6H12O6 + 602 -> 6CO2 + 6 H2O

    • C. 

      6CO2 + 6H2O -> C6H12O6 + 6O2

    • D. 

      Amino acids -> proteins

    • E. 

      Glucose + fructose -> fructose

  • 9. 
    If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to
    • A. 

      Add more of the enzyme

    • B. 

      Heat the solution to 99 C

    • C. 

      Add more substrate

    • D. 

      Add an allosteric inhibitor

    • E. 

      Add a noncompetitive inhibitor

  • 10. 
    Some bacteria are metabolically active in hot springs because
    • A. 

      They are able to maintain a lower internal temperature

    • B. 

      High temperatures make catalysis unnecessary

    • C. 

      Their enzymes have high optimal temperatures

    • D. 

      Their enzymes are completely insensitive to temperature

    • E. 

      They use molecules other than proteins or RNAs as their main catalysts

  • 11. 
    If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur?
    • A. 

      Additional product will be formed

    • B. 

      Additional substrate will be formed

    • C. 

      The reaction will change from endergonic to exergonic

    • D. 

      The free energy of the system will change

    • E. 

      Nothing; the reaction will stay at equilibrium

  • 12. 
    Which of the following is the smallest closed system
    • A. 

      A cell

    • B. 

      An organism

    • C. 

      An ecosystem

    • D. 

      Earth

    • E. 

      The universe

  • 13. 
    Which of the following is true of metabolism in its entirety in all organisms
    • A. 

      Metabolism depends on a constant supply of energy from food

    • B. 

      Metabolism depends on an organism's adequate hydration

    • C. 

      Metabolism uses all of an organism's resources

    • D. 

      Metabolism consists of all the energy transformation reactions in an organism

    • E. 

      Metabolism manages the increase of entropy in an organism

  • 14. 
    The mathematical expression for the change in free energy of a system is ^G = ^H - T^S. Which of the following is (are) correct?
    • A. 

      ^S is the change in enthalpy, a measure of randomness

    • B. 

      ^H is the change in entropy, the energy available to do work

    • C. 

      ^G is the change in free energy

    • D. 

      T is the temperature in degrees Celsius

  • 15. 
    A system at chemical equilibrium
    • A. 

      Consumes energy at a steady rate

    • B. 

      Releases energy at a steady rate

    • C. 

      Consumes or releases energy, depending on whether it is exergonic or endergonic

    • D. 

      Has zero kinetic energy

    • E. 

      Con do no work

  • 16. 
    Which of the following is true for all exergonic reactions?
    • A. 

      The products have more total energy than the reactants

    • B. 

      The reaction proceeds with a net release of free energy

    • C. 

      The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants

    • D. 

      A net input of energy from the surroundings is required for the reactions to proceed

    • E. 

      The reactions are rapid

  • 17. 
    Chemical equilibrium is relatively rare in living cells. Which of the following could be an example of a reaction at chemical equilibrium in a cell?
    • A. 

      A reaction in which the free energy at equilibrium is higher than the energy content at any point away from equilibrium

    • B. 

      A chemical reaction in which the entropy change in the reaction is just balanced by an opposite entropy change in the cell's suuroundings

    • C. 

      An endergonic reaction in an active metabolic pathway where the energy for that reaction is supplied only by heat from the environment

    • D. 

      A chemical reaction in which both the reactants and products are not being produced or used in any active metabolic pathway

    • E. 

      No possibility of having chemical equilibrium in any living cell

  • 18. 
    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?
    • A. 

      +^H, +^S,+^G

    • B. 

      +^H, -^S, -^G

    • C. 

      +^H, -^S, +^G

    • D. 

      -^H, -^S, +^G

    • E. 

      -^H, +^S, +^G

  • 19. 
    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:
    • A. 

      +^G, +^H,+^S

    • B. 

      +^G, +^H, -^S

    • C. 

      +^G, -^H, -^S

    • D. 

      -^G, +^H, +^S

    • E. 

      -^G, -^H, -^S

  • 20. 
    A chemical reaction that has a positive ^G is correctly described as
    • A. 

      Endergonic

    • B. 

      Endothermic

    • C. 

      Enthalpic

    • D. 

      Spontaneous

    • E. 

      Exothermic

  • 21. 
    Which of the following best describes enthalpy (H)
    • A. 

      The total kinetic energy of a system

    • B. 

      The heat content of a chemical system

    • C. 

      The system's entropy

    • D. 

      The cell's energy equilibrium

    • E. 

      The condition of a cell that is not able to react

  • 22. 
    22) For the hydrolysis of ATP to ADP +P i, the free energy change is -7.3 kcal/mol under standard conditions (1 M concentration of both reactants and products). In the cellular environment, however, the free energy change is about -13 kcal/mol. What can we conclude about the free energy change for the formation of ATP from ADP and P i under cellular conditions?
    • A. 

      It is +7.3 kcal/mol.

    • B. 

      It is less than +7.3 kcal/mol.

    • C. 

      It is about +13 kcal/mol.

    • D. 

      It is greater than +13 kcal/mol.

    • E. 

      The information given is insufficient to deduce the free energy change.

  • 23. 
    When 10,000 molecules of ATP are hydrolyzed to ADP and i 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?
    • A. 

      Cells are open systems, but a test tube is a closed system.

    • B. 

      Cells are less efficient at heat production than nonliving systems.

    • C. 

      The hydrolysis of ATP in a cell produces different chemical products than does the reaction in a test tube.

    • D. 

      The reaction in cells must be catalyzed by enzymes, but the reaction in a test tube does not need enzymes.

    • E. 

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

  • 24. 
    Which of the following statements is true concerning catabolic pathways?
    • A. 

      They combine molecules into more energy-rich molecules

    • B. 

      They supply energy, primarily in the form of ATP, for the cell's work

    • C. 

      They are endergonic

    • D. 

      They are spontaneous and do not need enzyme catalysis

    • E. 

      They build up complex molecules such as protein from simpler compounds

  • 25. 
    When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?
    • A. 

      It is used to power yet more cellular work

    • B. 

      It is used to store energy as more ATP

    • C. 

      It is used to generate ADP from nucleotide precursors

    • D. 

      It is lost to the environment

    • E. 

      It is transported to specific organs such as the brain

  • 26. 
    When ATP releases some energy, it also releases inorganic phosphate. What purpose does this serve (if any) in the cell?
    • A. 

      The phosphate can only be used as an excretory waste

    • B. 

      The phosphate can only be used to regenerate more ATP

    • C. 

      The phosphate can be added to water and excreted as a liquid

    • D. 

      The phosphate may be incorporated into any molecule that contains phosphate

    • E. 

      It enters the nucleus to affect gene expression

  • 27. 
    29) A number of systems for pumping ions across membranes are powered by ATP. Such ATP-powered pumps are often called ATPases although they don't often hydrolyze ATP unless they are simultaneously transporting ions. Because small increases in calcium ions in the cytosol can trigger a number of different intracellular reactions, cells keep the cytosolic calcium concentration quite low under normal conditions, using ATP-powered calcium pumps. For example, muscle cells transport calcium from the cytosol into the membranous system called the sarcoplasmic reticulum (SR). If a resting muscle cell's cytosol has a free calcium ion concentration of 10-7 while the concentration in the SR is 10-2, then how is the ATPase acting?
    • A. 

      A) ATPase activity must be powering an inflow of calcium from the outside of the cell into the SR.

    • B. 

      B) ATPase activity must be transferring Pi to the SR to enable this to occur.

    • C. 

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

    • D. 

      D) ATPase activity must be opening a channel for the calcium ions to diffuse back into the SR along the concentration gradient.

    • E. 

      E) ATPase activity must be routing calcium ions from the SR to the cytosol, and then to the cell's environment.

  • 28. 
    Which of the following statements is true about enzyme-catalyzed reactions?
    • A. 

      The reaction is faster than the same reaction in the absense of the enzyme

    • B. 

      The free energy change of the reaction is opposite from the reaction that occurs in the absense of the enzyme

    • C. 

      The reaction always goes in the direction toward chemical equilibrium

    • D. 

      Enzyme-catalyzed reaction require energy to activate the enzyme

    • E. 

      Enzyme-catalyzed reactions release more free energy than noncatalyzed reactions

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