In response to a drop in blood pressure, which hormone/enzyme is secreted by specialized cells in the kidney

Can you identify which of the following groups of organisms are, or are not, populations? a. the american bison (bison bison) and grey wolves (canis lupus) currently living in yellowstone national parkb. all of the rainbow trout (oncorhynchus mykiss that) that have ever lived in lake eriec. the group of american bison (bison bison) currently living in yellowstone national parkd. a group of calliope hummingbirds (selasphorus calliope) and a group of rufous hummingbirds (selasphorus rufus) living in the same new hampshire woodse. the northern cardinals (cardinalis cardinalis) living on opposite shores of lake champlain f. all of the whales currently living in the atlantic ocean off cape cod, massachusetts

Why reason best illustrates why hershey and chase chose to use viruses in their experiment?

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.