Which cells become activated only if the antigen appears in the body at a later date?

In the ocean why are the greatest amount of primary producers found in the epipelagic zone and how does that affect biodiversity

The sea slug that considered to be a photosyntheesizing animal

16 select the correct answer from each drop-down menu. sharks, whales, and dolphins share similar features such as body shape and the position of fins. hoy while whales and dolphins have lungs. these differences indicate that the organisms share a comme whales also possess a vestigial pelvic bone. the presence of the pelvis bone may indicate that whales reset next