Select the statement that is true concerning primary teeth.

there are 27 primary teeth, and the molars are permanent.
there are 32 primary teeth, and most children lose these teeth due to decay because they are never very strong.
there are 20 primary teeth, and by 24 months of age most children have all 20.
there are 24 primary teeth, and no new primary teeth appear after 13 months.

How do adaptation affect a species?

Which muscle is responsible for inhalation ?

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.