Which group of substances includes steroids and triglycerides?

The correct answer is lipids because this group of substances is characterized by their hydrophobic or amphipathic properties, which are largely due to their nonpolar molecular structures. Steroids and triglycerides are both classified as lipids due to their similar chemical structures and their role in biological systems.

Steroids are a type of lipid characterized by a core structure of four fused carbon rings, which can modify to produce various hormones, such as testosterone and estrogen. Triglycerides consist of glycerol and three fatty acid chains, serving primarily as a long-term energy storage form in organisms.

In contrast, proteins are polymers made up of amino acids and play a diverse range of functions, including catalysis, signaling, and structural support. Carbohydrates, which include sugars and starches, are primarily energy sources and structural elements in organisms. Nucleic acids, such as DNA and RNA, are responsible for storing and transferring genetic information. Thus, the unique characteristics and functions of steroids and triglycerides distinctly identify them as part of the lipid group.