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15.7: Chapter 7 exercises

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  • Multiple Choice

    Which of the following is an organism that obtains its energy from the transfer of electrons originating from chemical compounds and its carbon from an inorganic source?

    A. chemoautotroph
    B. chemoheterotroph
    C. photoheterotroph
    D. photoautotroph

    Which of the following molecules is reduced?

    A. NAD+
    B. FAD
    C. O2
    D. NADPH

    Enzymes work by which of the following?

    A. increasing the activation energy
    B. reducing the activation energy
    C.making exergonic reactions endergonic
    D. making endergonic reactions exergonic

    To which of the following does a competitive inhibitor most structurally resemble?

    A. the active site
    B. the allosteric site
    C. the substrate
    D. a coenzyme

    Which of the following are organic molecules that help enzymes work correctly?

    A. cofactors
    B. coenzymes
    C. holoenzymes
    D. apoenzymes

    Fill in the Blank

    Processes in which cellular energy is used to make complex molecules from simpler ones are described as ________.

    The loss of an electron from a molecule is called ________.

    The part of an enzyme to which a substrate binds is called the ________.


    Competitive inhibitors bind to allosteric sites.

    Short Answer

    In cells, can an oxidation reaction happen in the absence of a reduction reaction? Explain.

    What is the function of molecules like NAD+/NADH and FAD/FADH2 in cells?

    Multiple Choice

    An operon of genes encoding enzymes in a biosynthetic pathway is likely to be which of the following?

    A. inducible
    B. repressible
    C. constitutive
    D. monocistronic

    An operon encoding genes that are transcribed and translated continuously to provide the cell with constant intermediate levels of the protein products is said to be which of the following?

    A. repressible
    B. inducible
    C. constitutive
    D. activated

    Which of the following conditions leads to maximal expression of the lac operon?

    A. lactose present, glucose absent
    B. lactose present, glucose present
    C. lactose absent, glucose absent
    D. lactose absent, glucose present

    Which of the following is a type of regulation of gene expression unique to eukaryotes?

    A. attenuation
    B. use of alternate σ factor
    C. chemical modification of histones
    D. alarmones

    Fill in the Blank

    The DNA sequence, to which repressors may bind, that lies between the promoter and the first structural gene is called the ________.

    The prevention of expression of operons encoding substrate use pathways for substrates other than glucose when glucose is present is called _______.

    Short Answer

    What are two ways that bacteria can influence the transcription of multiple different operons simultaneously in response to a particular environmental condition?

    Critical Thinking

    The following figure is from Monod’s original work on diauxic growth showing the growth of E. coli in the simultaneous presence of xylose and glucose as the only carbon sources. Explain what is happening at points A–D with respect to the carbon source being used for growth, and explain whether the xylose-use operon is being expressed (and why). Note that expression of the enzymes required for xylose use is regulated in a manner similar to the expression of the enzymes required for lactose use.

    A graph with time (hours) on the X axis and density of bacteria on the Y axis. An upward slope is labeled A. Next, is a plateau labeled B. Next is an upward slope labeled C. And finally is a plateau labeled D.

    Multiple Choice

    During which of the following is ATP not made by substrate-level phosphorylation?

    A. Embden-Meyerhof pathway
    B. Transition reaction
    C. Krebs cycle
    D. Entner-Doudoroff pathway

    Which of the following products is made during Embden-Meyerhof glycolysis?

    A. NAD+
    B. pyruvate
    C. CO2
    D. two-carbon acetyl

    During the catabolism of glucose, which of the following is produced only in the Krebs cycle?

    A. ATP
    B. NADH
    C. NADPH
    D. FADH2

    Which of the following is not a name for the cycle resulting in the conversion of a two-carbon acetyl to one ATP, two CO2, one FADH2, and three NADH molecules?

    A. Krebs cycle
    B. tricarboxylic acid cycle
    C. Calvin cycle
    D. citric acid cycle


    Glycolysis requires oxygen or another inorganic final electron acceptor to proceed.

    Fill in the Blank

    Per turn of the Krebs cycle, one acetyl is oxidized, forming ____ CO2, ____ ATP, ____ NADH, and ____ FADH2molecules.

    Most commonly, glycolysis occurs by the ________ pathway.

    Short Answer

    What is substrate-level phosphorylation? When does it occur during the breakdown of glucose to CO2?

    Why is the Krebs cycle important in both catabolism and anabolism?

    Critical Thinking

    What would be the consequences to a cell of having a mutation that knocks out coenzyme A synthesis?

    Multiple Choice

    Which is the location of electron transports systems in prokaryotes?

    A. the outer mitochondrial membrane
    B. the cytoplasm
    C. the inner mitochondrial membrane
    D. the cytoplasmic membrane

    Which is the source of the energy used to make ATP by oxidative phosphorylation?

    A. oxygen
    B. high-energy phosphate bonds
    C. the proton motive force
    D. Pi

    A cell might perform anaerobic respiration for which of the following reasons?

    A. It lacks glucose for degradation.
    B. It lacks the transition reaction to convert pyruvate to acetyl-CoA.
    C. It lacks Krebs cycle enzymes for processing acetyl-CoA to CO2.
    D. It lacks a cytochrome oxidase for passing electrons to oxygen.

    In prokaryotes, which of the following is true?

    A. As electrons are transferred through an ETS, H+ is pumped out of the cell.
    B. As electrons are transferred through an ETS, H+ is pumped into the cell.
    C. As protons are transferred through an ETS, electrons are pumped out of the cell.
    D. As protons are transferred through an ETS, electrons are pumped into the cell.

    Which of the following is not an electron carrier within an electron transport system?

    A. flavoprotein
    B. ATP synthase
    C. ubiquinone
    D. cytochrome oxidase

    Fill in the Blank

    The final ETS complex used in aerobic respiration that transfers energy-depleted electrons to oxygen to form H2O is called ________.

    The passage of hydrogen ions through ________ down their electrochemical gradient harnesses the energy needed for ATP synthesis by oxidative phosphorylation.


    All organisms that use aerobic cellular respiration have cytochrome oxidase.

    Short Answer

    What is the relationship between chemiosmosis and the proton motive force?

    How does oxidative phosphorylation differ from substrate-level phosphorylation?

    How does the location of ATP synthase differ between prokaryotes and eukaryotes? Where do protons accumulate as a result of the ETS in each cell type?

    Multiple Choice

    Which of the following is the purpose of fermentation?

    A. to make ATP
    B. to make carbon molecule intermediates for anabolism
    C. to make NADH
    D. to make NAD+

    Which molecule typically serves as the final electron acceptor during fermentation?

    A. oxygen
    B. NAD+
    C. pyruvate
    D. CO2

    Which fermentation product is important for making bread rise?

    A. ethanol
    B. CO2
    C. lactic acid
    D. hydrogen gas

    Which of the following is not a commercially important fermentation product?

    A. ethanol
    B. pyruvate
    C. butanol
    D. penicillin

    Fill in the Blank

    The microbe responsible for ethanol fermentation for the purpose of producing alcoholic beverages is ________.

    ________ results in the production of a mixture of fermentation products, including lactic acid, ethanol and/or acetic acid, and CO2.

    Fermenting organisms make ATP through the process of ________.


    Match the fermentation pathway with the correct commercial product it is used to produce:

    ___acetone-butanol-ethanol fermentation a. bread
    ___alcohol fermentation b. pharmaceuticals
    ___lactic acid fermentation c. Swiss cheese
    ___mixed acid fermentation d. yogurt
    ___propionic acid fermentation e. industrial solvents

    Short Answer

    Why are some microbes, including Streptococcus spp., unable to perform aerobic respiration, even in the presence of oxygen?

    How can fermentation be used to differentiate various types of microbes?

    Critical Thinking

    The bacterium E. coli is capable of performing aerobic respiration, anaerobic respiration, and fermentation. When would it perform each process and why? How is ATP made in each case?

    Multiple Choice

    Which of the following molecules is not produced during the breakdown of phospholipids?

    A. glucose
    B. glycerol
    C. acetyl groups
    D. fatty acids

    Caseinase is which type of enzyme?

    A. phospholipase
    B. lipase
    C. extracellular protease
    D. intracellular protease

    Which of the following is the first step in triglyceride degradation?

    A. removal of fatty acids
    B. β-oxidation
    C. breakage of fused rings
    D. formation of smaller peptides

    Fill in the Blank

    The process by which two-carbon units are sequentially removed from fatty acids, producing acetyl-CoA, FADH2, and NADH is called ________.

    The NADH and FADH2 produced during β-oxidation are used to make ________.

    ________ is a type of medium used to detect the production of an extracellular protease called caseinase.

    Short Answer

    How are the products of lipid and protein degradation connected to glucose metabolism pathways?

    What is the general strategy used by microbes for the degradation of macromolecules?

    Critical Thinking

    Do you think that β-oxidation can occur in an organism incapable of cellular respiration? Why or why not?

    Multiple Choice

    During the light-dependent reactions, which molecule loses an electron?

    A. a light-harvesting pigment molecule
    B. a reaction center pigment molecule
    C. NADPH
    D. 3-phosphoglycerate

    In prokaryotes, in which direction are hydrogen ions pumped by the electron transport system of photosynthetic membranes?

    A. to the outside of the plasma membrane
    B. to the inside (cytoplasm) of the cell
    C. to the stroma
    D. to the intermembrane space of the chloroplast

    Which of the following does not occur during cyclic photophosphorylation in cyanobacteria?

    A. electron transport through an ETS
    B. photosystem I use
    C. ATP synthesis
    D. NADPH formation

    Which are two products of the light-dependent reactions are ________.

    A. glucose and NADPH
    B. NADPH and ATP
    C. glyceraldehyde 3-phosphate and CO2
    D. glucose and oxygen


    Photosynthesis always results in the formation of oxygen.

    Fill in the Blank

    The enzyme responsible for CO2 fixation during the Calvin cycle is called ________.

    The types of pigment molecules found in plants, algae, and cyanobacteria are ________ and ________.

    Short Answer

    Why would an organism perform cyclic phosphorylation instead of noncyclic phosphorylation?

    What is the function of photosynthetic pigments in the light-harvesting complex?

    Critical Thinking

    Is life dependent on the carbon fixation that occurs during the light-independent reactions of photosynthesis? Explain.

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