Final answer:
Molecules with both polar and nonpolar groups are called amphipathic. Phospholipids are an example of amphipathic molecules, comprising a hydrophilic head and hydrophobic tails, facilitating the formation of cell membranes. Hence, option (a) is correct.
Step-by-step explanation:
Molecules that contain both polar (water-loving) and nonpolar (water-fearing) groups are known as amphipathic molecules. These molecules are characterized by their dual affinity for both water and lipid environments. An example of an amphipathic molecule is a phospholipid, which plays a crucial role in forming cell membranes.
Phospholipids have a polar head (typically containing phosphate groups) that is hydrophilic and interacts with water, and nonpolar fatty acid tails that are hydrophobic and avoid water. This dual nature is essential in the formation of cellular structures like the lipid bilayer, where the polar heads face outwards towards the aqueous environment, while the nonpolar tails face inwards, away from the water.