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    water, ph and macromolecules




    1).
    Which of the following organic groups are found in naturally occuring amino acids?
    A   Guanidinium ion   
    B   Indole   
    C   Imidazole   
    D   All of these   
    ANS: D - All of these

    No answer description available for this question

    2).
    Polyprotic acids such as H3PO4, can act as acid-base buffers
    A   only in combination with polyprotic bases   
    B   if their concentration is kept low   
    C   at pH values around neutrality   
    D   at pH values around any of their pKa's   
    ANS: D - at pH values around any of their pKa's

    No answer description available for this question

    3).
    The pH of a solution is determined by
    A   concentration of salt   
    B   relative concentration of acids and bases   
    C   dielectric constant of the medium   
    D   environmental effect   
    ANS: B - relative concentration of acids and bases

    No answer description available for this question

    4).
    The reactions of molecules
    A   are the reactions of the functional groups   
    B   are independent of the functional groups   
    C   require an enzyme in all cases   
    D   all of the above   
    ANS: A - are the reactions of the functional groups

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    5).
    Which of the following indicates that the pK of an acid is numerically equal to the pH of the solution when the molar concentration of the acid and its conjugate base are equal?
    A   Michaelis-Menten equation   
    B   Haldanes equation   
    C   Henderson-Hasselbalch equation   
    D   Hardy-Windberg law   
    ANS: C - Henderson-Hasselbalch equation

    No answer description available for this question

    6).
    Molecules in which the atoms are held together by __________ bonds have the strongest chemical linkages.
    A   noncovalent   
    B   covalent   
    C   ionic   
    D   hydrogen   
    ANS: B - covalent

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    7).
    Salt dissolves well in water as water molecules
    A   form hydrogen bonds with the positively and negatively charged ions   
    B   make nonpolar covalent bonds with the positively charged ions only   
    C   surround the ions because of their charge but do not form hydrogen bonds   
    D   share electrons with the ions to make polar covalent bonds   
    ANS: C - surround the ions because of their charge but do not form hydrogen bonds

    No answer description available for this question

    8).
    Buffer solutions
    A   will always have a pH of 7   
    B   are rarely found in living systems   
    C   cause a decrease in pH when acids are added to them.   
    D   tend to maintain a relatively constant pH.   
    ANS: D - tend to maintain a relatively constant pH.

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    9).
    A Bronsted acid becomes __________ upon losing a proton
    A   highly reactive   
    B   its conjugate acid   
    C   its conjugate base   
    D   a hydronium ion   
    ANS: C - its conjugate base

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    10).
    Most of the important functional groups in biological molecules contain
    A   oxygen and/or nitrogen and are acidic   
    B   oxygen and a phosphate   
    C   nitrogen and a phosphate   
    D   oxygen and/or nitrogen and are polar   
    ANS: A - oxygen and/or nitrogen and are acidic

    No answer description available for this question