What are the various levels of organization in the human body, as a baby grows in the mothers womb, grows and develops until birth?

What must be true for natural selection to heppen

Body systems are not completely independent they integrate and work together describe one example of the integration between body systems

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.