Organic Molecules 2011

							AP Biology                                      Name ___________________________________
Organic Molecules Questions

Multiple Choice. Circle the letter of the BEST answer.
1.     Substances that are nonpolar and repelled by water are ________.

a.   hydrolyzed
b.   nonpolar
c.   hydrophilic
d.   hydrophobic
2.     A hydrogen bond is ________.

a.   a sharing of a pair of electrons between a hydrogen nucleus and an oxygen nucleus
b.   a sharing of a pair of electrons between a hydrogen nucleus and either an oxygen or a
     nitrogen nucleus
c.   formed when an electronegative atom of a molecule weakly interacts with a hydrogen atom
     that is already participating in a separate polar covalent bond
d.   none of these

3.     A nonpolar covalent bond implies that ________.

a.   one negative atom bonds with a hydrogen atom
b.   it is a double bond
c.   there is no difference in charge at the ends (the two poles) of the bond
d.   atoms of different elements do not exert the same pull on shared electrons
4.     This type of chemical bond contributes to the shape of large molecules.

a.   hydrogen
b.   ionic
c.   covalent
d.   inert
e.   single

5.     Which of the following properties of water protects aquatic organisms during a long, cold winter?

a.   cohesion
b.   solvent properties
c.   temperature-stabilizing
d.   none of these
6.     Amino acids are linked by ________ bonds to form the primary structure of a protein.

a.   disulfide
b.   hydrogen
c.   ionic
d.   peptide
7.      Proteins ________.

a.    are weapons against disease-causing bacteria and other invaders
b.    are composed of amino acid subunits
c.    may act as hormones
d.    may function as enzymes
e.    all of these
8.      Which of the following does not belong to the lipid class of organic molecules?

a.    sterols
b.    waxes
c.    phospholipids
d.    glycoproteins
e.    triglycerides
9.      DNA ________.

a.    is one of the adenosine phosphates
b.    is one of the nucleotide coenzymes
c.    contains protein-building instructions
d.    is composed of monosaccharides
10.     Most of the chemical reactions in cells must have ________ present before they proceed.

a.    RNA
b.    salt
c.    enzymes
d.    fats
e.    chitin
11.     Carbon is part of so many different substances because ________.

a.    carbon generally forms two covalent bonds with a variety of other atoms
b.    a carbon atom generally forms four covalent bonds with a variety of atoms
c.    carbon ionizes easily
d.    carbon is a polar compound
12.     Which of the following levels of protein structure is not correctly linked to its description?

a.    primary--the linear sequence of amino acids
b.    secondary--coiling of a polypeptide due to the action of hydrogen bonds
c.    tertiary--interactions between the domains of a protein
d.    quaternary--chemical interactions between multiple polypeptide chains
e.    all of these are correct
13.     ________ are molecules used by cells as structural materials, energy transport molecules, or storage
forms of energy.

a.    Lipids
b.    Nucleic acids
c.    Carbohydrates
d.    Proteins
14.     Hydrolysis could be correctly described as the ________.

a.    heating of a compound in order to drive off its excess water and concentrate its volume
b.    breaking of a long-chain compound into its subunits by adding water molecules to its
      structure between the subunits
c.    linking of two or more molecules by the removal of one or more water molecules
d.    constant removal of hydrogen atoms from the surface of a carbohydrate
e.    an example of a condensation class of reactions
15.     Genetic instructions are encoded in the base sequence of ________; molecules of ________ function
in processes using genetic instructions to construct proteins.

a.    DNA; DNA
b.    DNA; RNA
c.    RNA; DNA
d.    RNA; RNA

Matching. Place the letter of the BEST answer in the blank

16.     For each of the following, choose the correct class of carbohydrates with which the indicated term is
associated. Answers may be used more than once.

a.    oligosaccharides
b.    polysaccharides
c.    monosaccharides

_____ (1)      "complex carbohydrates"
_____ (2)      chitin
_____ (3)      disaccharides
_____ (4)      ribose and deoxyribose
_____ (5)      lactose, sucrose, and maltose
_____ (6)      glucose and fructose
_____ (7)      starch and glycogen
_____ (8)      cellulose
17.     Choose the most appropriate answer for each term.

a.    A coiled or extended pattern of protein structure caused by regular intervals of H bonds
b.    Three or more amino acids joined in a linear chain
c.    Proteins with linear or branched oligosaccharides covalently bonded to them; found on
      animal cell surfaces, in cell secretion, or on blood proteins
d.    Folding of a protein through interactions among R groups of a polypeptide chain
e.    Form when freely circulating blood proteins encounter and combine with cholesterol, or
      phospholipids
f.    The type of covalent bond linking one amino acid to another
g.    HLAs and hemoglobin are examples of this level of protein structure
h.    Breaking weak bonds in large molecules (such as protein) to change their shape so they no
      longer function
i.    A self-organized polypeptide chain that functions as a stable unit
j.    Lowest level of protein structure; has a linear, unique sequence of amino acids
k.    A small organic compound having an amino group, an acid group, a hydrogen atom, and an
      R group
l.    The most diverse of all the large biological molecules; constructed from pools of only 20
      kinds of amino acids
m.    A group of proteins that contribute to cell shape and organization
n.    A chemical bond between polypeptide chains that uses two sulfur atoms
o.    Enzymes typically belong to this group of proteins


_____ (1)      amino acid
_____ (2)      disulfide bridges
_____ (3)      peptide bond
_____ (4)      polypeptide chain
_____ (5)      primary structure
_____ (6)      proteins
_____ (7)      secondary structure
_____ (8)      tertiary structure
_____ (9)      domain
_____ (10)     quaternary structure
_____ (11)     lipoproteins
_____ (12)     glycoproteins
_____ (13)     denaturation
_____ (14)     fibrous proteins
_____ (15)     globular proteins
18.    For each of the following, choose the class of organic molecule to which the item belongs. Choices
may be used more than once.

a.   lipids
b.   nucleic acids
c.   proteins
d.   carbohydrates


_____ (1)      glycoproteins
_____ (2)      phospholipids
_____ (3)      glycogen
_____ (4)      adenosine triphosphate
_____ (5)      sucrose and maltose
_____ (6)      triglycerides
_____ (7)      DNA and RNA
_____ (8)      HLAs and hemoglobin
_____ (9)      cholesterol
_____ (10)     glycogen and starch
_____ (11)     waxes


19.     Study the structural formulas of the two adjacent amino acids. Identify the enzyme action causing
formation of a covalent bond and a water molecule (through a condensation reaction) by circling an H atom
from one amino acid and an -OH group from the other amino acid. Also circle the covalent bond that formed
the dipeptide.
20.      In the following diagram, identify condensation reaction sites between the two glucose molecules by
circling the components of the water removed that allow a covalent bond to form between the glucose
molecules (text Figure 3.8, p.40). Note that the reverse reaction is hydrolysis and that both condensation and
hydrolysis reactions require enzymes in order to proceed efficiently.




21.    In the answer blanks, label the molecules shown as saturated or unsaturated. For the unsaturated
molecules, circle the regions that make them unsaturated.




a.   ___________________
b.   ___________________
c.   ___________________
22.      Using a condensation reaction, combine glycerol with three fatty acids to form a triglyceride. In the
diagram to the left, circle the participating atoms that will identify three covalent bonds. In the diagram to the
right, circle the resulting covalent bonds.




23.     In the model of an amino acid below, label the R group, amino group, and carboxyl group.




a.    __________
b.    __________
c.    __________

24.     In the diagram of a nucleotide below, label the phosphate groups, nitrogenous base, and five-carbon
sugar subunits.




a.    __________
b.    __________
c.    __________
25.     In the diagram of a single-stranded nucleic acid molecule, encircle as many complete nucleotides as
possible. How many complete nucleotides are present?
Organic Molecules Questions
Answer Section

SHORT ANSWER

      1. ANS:
         d
      2. ANS:
         c
      3. ANS:
         c
      4. ANS:
         a
      5. ANS:
         c
      6. ANS:
         d
      7. ANS:
         e
      8. ANS:
         d
      9. ANS:
         c
     10. ANS:
         c
     11. ANS:
         b
     12. ANS:
         e
     13. ANS:
         c
     14. ANS:
         b
     15. ANS:
         b

     16. ANS:

        (1)     b
        (2)     b
        (3)     a
        (4)     c
        (5)     a
        (6)     c
        (7)     b
        (8)     b
  17.      ANS:

    (1)    k
    (2)    n
    (3)    f
    (4)    b
    (5)    j
    (6)    l
    (7)    a
    (8)    d
    (9)    i
    (10)   g
    (11)   e
    (12)   c
    (13)   h
    (14)   m
    (15)   o
18. ANS:

   (1)     c
   (2)     a
   (3)     d
   (4)     b
   (5)     d
   (6)     a
   (7)     b
   (8)     c
   (9)     a
   (10)    d
   (11)    a

19. ANS:




20. ANS:
  21.      ANS:

   a.   unsaturated
   b.   saturated
   c.   unsaturated




22. ANS:




23. ANS:

   a.   R group
   b.   amino group
   c.   carboxyl group
24. ANS:

   a.   phosphate group
   b.   five-carbon sugar
   c.   nitrogenous base
25.     ANS:
  three