Which ecosystem--mountain, tundra, or taiga--do you think is most vulnerable to human activity? Provide reasoning for your choice. Plz help! this is a test i have to do and i dont know what to write!

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.

What is the major difference between a virus and a viroid?

Can result as a complication of diabetes due to damage to the arterial walls and excess fat in the blood.