1. One molecule of hormone triggers the synthesis of numerous molecules of mRNA, and each mRNA results in the synthesis of numerous molecules of the protein for which it codes. Thus, you could show at least a three-step enzyme amplification diagram with hormone, mRNA, and protein as the three steps. If the protein is an enzyme, then its product could be shown as a fourth step.

2. Despite the bad reputation of cholesterol, it is essential to human life and a complete lack of it would be worse than an excess. Its absence would cause a weakening of plasma membranes, a lack of myelin and therefore severe nervous system dysfunction, and a lack of steroid hormones such as aldosterone, glucocorticoids, and sex steroids.

3. In toxic goiter, there is excessive secretion of thyroid hormone. This results in a high metabolic rate, leading to excess heat production and profuse sweating.

4. Neither metabotropic neurotransmitters nor peptide hormones can enter their target cells. They bind to surface receptors and activate second messengers such as cAMP.

5. Those who use anabolic steroids take doses that are many times higher than the natural level of sex steroids in the body. In response to such continual overstimulation, target cells down-regulate and become less sensitive to the natural hormones. This may be a factor in the atrophy of the testes, declining sperm production, and atrophy of the breasts and uterus.

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