What are the two main types of hormones?

Hormones are classified primarily based on their chemical structure, which dictates how they function in the body. The correct classification distinguishes between lipid-based (steroid) hormones and peptide or amine hormones.

Lipid or steroid hormones are derived from cholesterol, making them fat-soluble. This solubility allows them to easily cross cell membranes and bind to intracellular receptors. Once inside the cell, they influence gene expression and protein synthesis directly, which leads to long-lasting effects in target tissues. Examples include cortisol and testosterone.

On the other hand, peptide and amine hormones are typically water-soluble and include hormones formed from amino acids. These hormones cannot pass through cell membranes and instead bind to receptors on the surface of target cells. This binding triggers a cascade of cellular responses involving secondary messengers, leading to various physiological effects. Insulin and adrenaline (epinephrine) exemplify this group.

The other options do not encompass the primary categories of hormones. Simple sugars and complex carbohydrates, as well as nucleic acids and proteins, do not accurately reflect the hormonal classifications based on their functions or structures. Hence, the identification of lipid/steroid and peptide/amine as the two main types effectively captures the primary ways hormones are categorized in biology.