A)is activated immediately upon infection.
B)depends on a newly infected animal's previous exposure to the same pathogen.
C)is based on recognition of antigens that are specific to different pathogens.
D)is found only in vertebrate anim
- usually for animals that lack a circulatory system
-functions in both digestion and distribution of substances throughout the body
General Properties of Circulatory Systems
- has circulatory fluid
- has a set of interconnecting ve