Sort the events according to whether or not they had a major effect on the history of life on Earth.
Global climate change
Mountain building
Changes to the genetic code
Changes to the size of Earth
Continental drift
Meteor impacts
Major Effect on the History of Life
Little or No Effect on the History of Life

When analyzing tree rings, what do scientists assume a thin ring indicates?

Where do the respiratory and circulatory systems meet? a. in the heart b. in the muscles c. in the lungs d. in the brain

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.