Advanced Placement (AP) Biology Practice Exam

What defines a polymer in biological terms?

1. It is a single monomer structure.

2. It consists of varying types of building blocks.

3. It is a long molecule made of similar building blocks.

4. It is a rigid structure that cannot change shape.

The correct answer is: It is a long molecule made of similar building blocks.

A polymer in biological terms is defined as a long molecule made of similar building blocks, known as monomers. This definition emphasizes the repetitive nature of polymers, where multiple monomers are linked together through covalent bonds to form a chain-like structure. In biological systems, common examples of polymers include proteins, nucleic acids, and polysaccharides. For instance, proteins are composed of amino acid monomers, whereas nucleic acids like DNA and RNA are made up of nucleotide monomers. The key aspect of polymers is their structure; the arrangement of the repeating units can lead to a wide variety of functional properties despite being built from similar monomeric units. This contributes extensively to the diversity of biological functions they can perform, such as catalyzing biochemical reactions, storing genetic information, or providing structural support. Understanding this foundational concept of polymers enables a deeper comprehension of larger biological concepts, such as enzyme function, genetic coding, and cellular structure, which rely heavily on polymeric molecules.