Final answer:
Hormones can function at very low concentrations and are produced by glands to regulate physiology and behavior. They are generally organic molecules and can be categorized into lipid-derived, amino acid-derived, and peptide hormones, with different properties affecting their mode of action.
Step-by-step explanation:
The correct statement about hormones is that c. Hormones can function at very low concentrations. Hormones are special chemical messengers produced by glands in multicellular organisms that regulate a wide array of physiological processes and behaviors. They are typically organic substances and can be classified into three basic types: lipid-derived, amino acid-derived, and peptide hormones.
Lipid-derived hormones, like testosterone and estrogen, are non-polar and can easily diffuse across cell membranes to interact with intracellular receptors. Amino acid-derived and peptide hormones, on the other hand, are not lipid-soluble and therefore cannot pass through the plasma membrane; they must bind to receptors on the surface of target cells. Hormones orchestrate a range of physiological responses by binding to these receptors, which can be present in a variety of tissues throughout the body, and not necessarily produced at the sites where they act.