I dont have the word bank
<span>Any size group of interacting parts that form a complex whole is a system. A
tectonic plate an energy source a system a sphere</span>
A) E<span>nergy flow is unidirectional; chemical elements can be recycled. energy can enter but cannot leave an ecosystem.
This is because in biology, energy is transferred from organism to organism and some energy is lost along the way. Each energy transfer results in a loss of energy, so that energy is always at a lower level and can never be returned to its original high energy level. On the other hand, chemical elements can form products, then that reaction can be reversed and break back down into reactants. Additionally, the law of conservation of matter says that matter can't be created or destroyed, only transferred from one form to another.</span>
Answer: Serotonin
Explanation:
Serotonin is an hormone, derived from the amino acid, tryptothan. It is involved in vasodilation, sleep regulation, mood changes, capillary permeability, and causes contraction of smooth muscles like that of the stomach to signal hunger.
Brain. Specifically the frontal lobe M1.
