A generalist species is able to survive in a wide variety of environmental conditions and can make use of lots of different resources. Generalist species have a big niche. Humans, rabbits, house flies, and raccoons would all fall under the generalist species list.
A specialist species can only thrive is a small variety of environmental conditions and/or only has a limited diet. Specialist species have a small niche. Pandas, koalas, and salamanders would all fall under the specialist species list.
Excess Nitrates in the water supply
The correct answer is antigens and epitope.
An antigen is a substance which triggers an immune response in an organism. This can be either a foreign substance, such as a pathogen, or a specific part of the host organism (in this case this is an autoimmune response). The presence of an antigen activates a specific part of the immune system, called antibody. Each antigen has a specific antibody, which is tailored by the immune system accordingly. More specifically, the antibody has a specific structure, called paratope, which is complementary and binds like a key to a specific structure of the antigen, called epitope.
