The answer is Catecholamine. It is any of a class of aromatic amines that includes a number of neurotransmitters such as epinephrine and dopamine. The adrenergic receptors are a class of G protein-coupled receptors that are targets of the catecholamines, especially norepinephrine (noradrenaline) and epinephrine (adrenaline). These three - catecholamine, peptide hormones and eicosanoids acts as extracellular membrane receptors which means that these receptors are embedded in the membranes of cells. They act in cell signaling by receiving (binding to) extracellular molecules.
Biosphere- where living things exist
hydro- referring to just the water
geosphere-referring to entire thing
atmosphere- the gases in the air
I think it is b
<span>Amphibia, Reptilia, Aves, and Mammalia</span>
THE ANSWER IS TRUE BECAUSE WATER AND SOIL PLAYS A GREAT PART IN THE EARTH'S CYCLE
