Scientifics consensus supports the idea that living organisms require oxygen. then, a scientist discovers a type of bacteria that metabolizes sulfur instead of oxygen, and thus survives in environments without oxygen. the scientist concludes that a diverse group of many different organisms could live in an oxygen-free enviroment. why should are some scientists skeptical of the scientist's results and conclusion?

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.

smooth muscle is composed of involuntary muscles found within the walls of organs and structures such as the esophagus, stomach, intestines, and blood vessels. those muscles push materials like food or blood through organs. unlike skeletal muscle, smooth muscle can never be under your control.