Toxin - A poisonous substance, often a protein, produced by the metabolic processes of living cells or organisms that can cause disease if introduced into the body.⏎
Transition Zone - The area, sometimes referred to as an ecotone, encompassing the edges of two distinct ecosystems, such as the area where a forest intersects with grassland.⏎
Virus - An infectious agent that is only capable of replicating itself inside the living cells of other organisms.⏎
Vector - An organism (usually an arthropod such as a flea, mosquito, or tick) that carries an infectious agent from one host to another.⏎