What are lipids characterized as?

Lipids are characterized as large, nonpolar organic molecules that do not dissolve in water, making the selected answer accurate. This property arises from their hydrophobic nature due to long hydrocarbon chains or ring structures, which lack polar functional groups. As a result, lipids, including fats, oils, and phospholipids, are insoluble in water, which is a critical feature that enables them to serve essential functions within living organisms, such as forming cellular membranes and storing energy.

In contrast, large polar molecules that dissolve in water, small ionic compounds, and simple carbohydrates possess characteristics that fundamentally differ from those of lipids. Polar molecules tend to interact favorably with water due to their charged regions, while ionic compounds dissociate in solution into charged ions. Simple carbohydrates are water-soluble and consist of small organic molecules that provide quick energy. These distinctions highlight why lipids are uniquely classified based on their nonpolar, hydrophobic properties.