17. (05.06 LC) A person drives her own personal vehicle to work two days of the week. Her commute to and from work is 42 miles a day, and her car averages 28 miles per gallon? How much gasoline
is the person conserving a day if she takes the train instead? (5 points)
O 1.5 gallons per day
O 3.0 gallons per day
O 4.5 gallons per day
0 5.5 gallons per day

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.