Adenosine triphosphate (atp) is important because it
a. catalyzes important chemical reactions
b. pumps potassium into and sodium out of nerve cells
c. holds energy in small amounts so it can be stored or used gradually
d. enzymes do their job.

The first signs of cellular differentiation occur in the blastocyst. why is cellular differentiation important for the development of a fully formed human infant?

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.

The cluster of developing cells from conception until birth is called an