A Level Biology Practice Exam

What are macromolecules characterized by?

1. High solubility in water

2. Simple structures with low molecular weight

3. Large complex structures with high molecular weight

4. Uniform chemical properties across all types

The correct answer is: Large complex structures with high molecular weight

Macromolecules are defined by their large and complex structures, which contribute to their high molecular weight. These structures can include polymers like proteins, nucleic acids, carbohydrates, and lipids, all of which are formed by the covalent bonding of smaller subunits or monomers. The intricacy of these macromolecules arises from their combinations and arrangements, leading to diverse functions within biological systems. For example, proteins are made up of amino acids linked together in specific sequences, leading to distinct three-dimensional shapes that determine their function. Similarly, nucleic acids like DNA and RNA consist of long chains of nucleotides, encoding genetic information. This complexity is essential for their roles in metabolism, genetics, and cell structure. In contrast, characteristics such as high solubility in water or uniform chemical properties do not universally apply to all macromolecules. Many of them, like lipids, are hydrophobic and not soluble in water, which is crucial for their function in forming membranes. Moreover, the diversity of structures and functions among different types of macromolecules means that they do not exhibit uniform chemical properties—each class of macromolecule has unique properties determined by its specific structure and constituents.