Biology CLEP Prep Practice Exam

A macromolecule that is part of a cell’s external structure is:

1. Lipid

2. Nucleic acid

3. Enzyme

4. Protein

The correct answer is: Protein

Proteins are a type of macromolecule that contribute to the external structure of a cell. Lipids and nucleic acids are important for various functions within the cell, but they do not directly contribute to the cell's external structure. Enzymes are also important for cellular processes, but they are not considered a component of the cell's external structure. Therefore, D is the most accurate answer.