What is responsible for identifying foreign invaders and remains in the system for a long period of time.
a. red blood cells
b. axons
c. antigens
d. lymph nodes

1) what three conditions must be present for minerals to form through natural processes? 2) why are minerals considered inorganic substances? 3) how do oxides differ from other minerals that contain oxygen atoms? 4) how is a sulfide different from a sulfate? what makes native elements unique?

Identify the composition of oceanic and continental crystal rocks.in a model of earth’s interior,where would these rocks appear?

Which organelle breaks down sugar molecules that supply energy to the cell ?