The movement of mineral nutrients through organisms and their environment is called a cycle.
biological
bioaccumulation
biogeochemical
biochemical

imagine a line passing through the center of earth that goes through both the north pole and the south pole. this imaginary line is called an axis. earth spins around its axis, just as a top spins around its spindle. this spinning movement is called earth's rotation. at the same time that the earth spins on its axis, it also orbits, or revolves around the sun. this movement is called revolution.

straight probes are used primarily for measuring flow as it is approaching the test area. its geometry allows the probe to be mounted so that it is in the direct line of airflow.

i think the answer is a.keratin is the pigment responsible for skin color.