1.observation is made using one or more of the five senses. 2. An independent variable is a variable that's
changed in an experiment.
3. An explanation based on an observation is alan
4. There may be only one variable in an experiment.
5.observation is made using tools or measurement.
6. What's the difference between an observation and inference?

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.

Sperm are ejaculated from the corpora cavernosa of the penis. true or false

In 1859, the english naturalist charles darwin published a book entitled on the origin of the species. one of the major ideas that was presented in his book was the theory of natural selection. what was another idea that was presented in his book?