Final answer:
Lipids are hydrophobic molecules because they lack a charge and cannot dissolve in water. Examples include oil and water separation and the structure of cell membranes.
Step-by-step explanation:
Lipids are considered hydrophobic molecules because they are nonpolar, meaning they don't have a charge. Water, on the other hand, is a polar molecule with a slight positive charge on one end and a slight negative charge on the other. Like dissolves like, so polar molecules like water tend to dissolve in other polar substances. Since lipids lack a charge, they don't dissolve in water and instead repel it.
For example, consider oil and water. Oil is made up of lipids, and when you try to mix oil and water, they separate into distinct layers. This is because water molecules form hydrogen bonds with each other, while oil molecules don't form these bonds and are instead pushed away by the water.
Another example is the structure of cell membranes. Lipids called phospholipids make up the main component of cell membranes. The hydrophobic tails of these phospholipids point inward, facing each other, while the hydrophilic heads face outward, interacting with the watery environment inside and outside the cell.
Learn more about Lipids and hydrophobicity