Hemoglobin has tetrahedral structure containing four heme groups that surround a globin group.
Heme is ringlike organic compound also known as a porphyrin to which an iron atom is attached. There are four iron atoms that bind four oxygen atoms and transport them to tissues.
"evolution of populations over time" is <span>represented by the base root of a phylogenetic tree</span>
The armpit isn't the most precise but it is close. Under the tongue, across the forehead, as long as you have the proper tools (thermometer, the thermometer meant for foreheads) you should get a fairly accurate reading.
