Which of the following is a polymer of an amino sugar?

a.) cellulose
b.) chitin
c.) glycogen
d.) starch

The polymer of an amino sugar among the options provided is chitin (option b.).

To determine which of the given options is a polymer of an amino sugar, let's first understand what constitutes a polymer and what an amino sugar is.

A polymer is a large molecule made up of repeating subunits called monomers. These monomers join together through chemical bonds to form a long chain.

An amino sugar is a type of sugar that contains an amino group (-NH2) in place of a hydroxyl group (-OH) in its structure.

Now, let's analyze the options provided:

a.) Cellulose: Cellulose is not a polymer of an amino sugar. It is a polysaccharide composed of glucose monomers linked together through β-1,4-glycosidic bonds.

b.) Chitin: Chitin is the correct answer. It is a polymer of an amino sugar called N-acetylglucosamine. Chitin is commonly found in the exoskeletons of crustaceans, cell walls of fungi, and insect cuticles.

c.) Glycogen: Glycogen is not a polymer of an amino sugar. It is a highly branched polysaccharide made up of glucose units connected by α-1,4-glycosidic bonds.

d.) Starch: Starch is not a polymer of an amino sugar. It is also a polysaccharide composed of glucose monomers linked together, forming two forms: amylose (linear) and amylopectin (branched).

Therefore, the correct answer is b.) chitin, which is a polymer of an amino sugar (N-acetylglucosamine).