Your friend is scuba diving in Iceland at a mid-oceanic ridge and picks up a rock. He wants to know how old the rock is compared to the rock in Maryland. Explain to your friend which rock is the oldest and how you came to this conclusion. Use evidence from your notes.

Adigestive system that is a series of tubes beginning at the mouth and ending at the anus is a digestive system.

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.

In the respiration-photosynthesis cycle shown above, what are the products of cellular respiration that belong in box 2?