What is the target heart rate? How do you calculate it?

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.

This is an active transport mechanism by which cells pump sodium and potassium ions against the concentration gradient

Ican construct an argument based on data about the risk and benefits of renewable and nonrenewable energy sources