All the Black Widow spiders in the whole world A. species
B. population
C. ecosystem
D. community

Which term refers to the total dollar value of the goods and services produced in a country in a year?

This aquarium exhibits biotic and abiotic factors in an aquatic environment. one of the abiotic factors is

Which is an advantage of having memory cells when a pathogen is encountered for a second time. a) the memory cells are what proliferate into clones of cells in response to the binding of an antigen. b) memory cells are vital to the primary immune response in that they immediately recognize pathogens even at the first encounter. c) memory cells are essentially effector cells that are short lived and attack antigens even without having a receptor specific to that antigen. d) it ensures that more lymphocytes with a receptor specific to a particular antigen will be present than in a host that had never encountered that pathogen.