Question

Which of the following statements about hormones is incorrect?

• A. They are produced by endocrine glands.
• B. They are modified amino acids, peptides, or steroid molecules.
• C. They are carried by the circulatory system.
• D. They are used to communicate between different organisms.

Answer 1

The correct option is D They are used to communicate between different organisms.

A hormone is a regulatory chemical that is secreted into the blood by an endocrine gland or an organ of the body exhibiting an endocrine function. The blood (circulatory system) carries the hormone to every cell in the body, but only the target cells for a given hormone can respond to it. Another type of chemical messenger that is released into the environment is called a pheromone. These messengers aid in the communication between animals, not in the regulation within an animal. Hormones secreted by endocrine glands belong to four different chemical categories:
1. Polypeptides. These hormones are composed of chains of amino acids that are shorter than about 100 amino acids. Some important examples include insulin and antidiuretic hormone (ADH).
2. Glycoproteins. These are composed of a polypeptide significantly longer than 100 amino acids to which is attached a carbohydrate. Examples include follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
3. Amines. Derived from the amino acids tyrosine and tryptophan, they include hormones secreted by the adrenal medulla, thyroid, and pineal glands.
4. Steroids. These hormones are lipids derived from cholesterol, and include the hormones testosterone, estradiol, progesterone, and cortisol.