17. Two glucose molecules form
a. galactose.
b. lactose.
c. maltose.
d. fructose.

18. Starch is an example of a
a. monosaccharide.
b. polysaccharide.
c. peptide.
d. protein.

19. Cytosine always undergoes complementary base pairing with
a. adenine.
b. guanine.
c. thymine.
d. uracil.

20. The RNA nucleotide base that pairs with adenine of DNA is
a. cytosine.
b. guanine.
c. thymine.
d. uracil.