Which fossil organism is the oldest? What features does it have which are different from the youngest?

How are the tortoises that darwin observed on the galápagos islands similar to the anoles that losos studied

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.

Imagine you are introducing the lac operan and the trp operon to students who have never learned about it before. complete the table to compare the similarities and differences between the two operons