What a an endangered species?

What the theory that the sun goes around earth was replaced with the theory that earth goes around the sun this was an exaple of a

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.

Compare the parts of a cell and the cell as a whole to another common nonliving system (i. e., a car, a city, describe the parts of a cell and their primary function.