Question

1. what is a chemical messenger that travels through the body to a certain tissue, on which it exerts a special effect?

gland

hormone

target cell

Explanation:

Hormones are chemical messengers secreted by endocrine glands. They travel through the bloodstream to target cells or tissues, where they exert specific effects. For example, insulin (a hormone) travels to cells to regulate glucose uptake. Glands are organs that secrete substances (like hormones), and target cells are the cells that respond to a specific hormone. So, the term that fits the description of a "chemical messenger that travels through the body to a certain tissue, on which it exerts a special effect" is hormone.

Answer:

hormone