A Level Biology Practice Exam

What are amphiphilic molecules known for?

1. Being attracted to water only

2. Having hydrophobic and hydrophilic parts

3. Being soluble in lipids only

4. Repelling both water and fats

The correct answer is: Having hydrophobic and hydrophilic parts

Amphiphilic molecules are characterized by having both hydrophilic (water-attracting) and hydrophobic (water-repelling) regions within the same molecule. This unique structure allows them to interact with both polar and nonpolar substances, making them essential in various biological processes. For instance, in a biological context, amphiphilic molecules form the basis of cell membranes. Phospholipids are a common example of amphiphilic molecules; their hydrophilic heads interact with water, while their hydrophobic tails face away from it, thereby forming a bilayer that is crucial for cell integrity and function. This dual nature enables amphiphilic molecules to solubilize hydrophobic substances in an aqueous environment, which is vital for cellular processes, such as the formation of micelles or lipid bilayers. The presence of both types of regions in these molecules allows them to play essential roles in the structure and function of membranes and other cellular components.