Your school wins the homecoming football game against its biggest rival. you watch as the smallest cheerleader tries to lift up the heaviest linebacker in her excitement. as she strains against his 300-pound load and does not move him, what type of muscle contraction are her muscles experiencing?

Which of the following will not cause mass extinction? a. drastic change is weather b. geological change c. both a and b d. none of the above

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.

Why are scientists concerned about the depletion of the ozone levels in the stratosphere?