3. A general term for any substance acted on by an enzyme is a 1. coenzyme
2. vitamin
3. substrate
4. hormone

Cells destroy body cells infected by a virus or bacteria. killer t t memory t none of the above

What sentence best supports the statement that hormones are involved in the regulation of homeostasis? a. the hormone erythropoeitin increases the production of red blood cells when oxygen levels are low. b. the hormone oxytocin promotes labor contractions of the uterus during childbirth. c. the hormone melatonin induces sleep and its production is slowed by exposure to light. d. the hormone cortisol suppresses the immune system and is produced when the body is under stress.

Which are characteristics of flukes? check all that apply. a they are free living. b they are a type of flatworm. c they reproduce sexually. d they have eyespots. e they are segmented.