What two factors must be internally balanced for survival? a) energy and water b) water and materials c) materials and age d) materials & energy

What were the main components of earth’s earliest atmosphere? oxygen and ammonia hydrogen and helium oxygen and nitrogen hydrogen and nitrogen

Subduction zones form when an oceanic plate collides with another oceanic plate or continental plate. the continental crust is lighter and less dense than oceanic crust. continental crust's density is approximately 2.7 grams per cubic centimeter. oceanic crust is thinner and the average density is about 3.3 cubic centimeters. when the two crustal plates converge the oceanic plate always bends and subducts beneath a continental plate. once the oceanic crust subjects, the rocks are subjected to changes in heat and pressure. because of this, we would expect to find rocks in the area of a subduction. a) clastic b) igneous c) metamorphic d) sedimentary

What are antigens and antibodies? how are they involved in the body’s response to incompatible blood?