OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What best describes a monomer?

1. A complex protein structure

2. A long chain of polymers

3. A small, basic molecular unit

4. A type of lipid molecule

The correct answer is: A small, basic molecular unit

A monomer is best described as a small, basic molecular unit because it serves as the fundamental building block for larger molecules, known as polymers. In biological contexts, monomers can include simple sugars (monosaccharides), amino acids, and nucleotide bases, each of which can link together through chemical bonds to form more complex structures. Understanding that monomers are basic units is crucial for grasping how various biological macromolecules, such as proteins, carbohydrates, and nucleic acids, are synthesized and function in living organisms. This understanding highlights the relationship between monomers and polymers, emphasizing the process of polymerization where multiple monomers combine to create larger, more complex molecules.