Some variation must be present in a population in order for natural selection to take place. these variations arise from mutations in the dna and what?

the growth of the plants is affected by the heat of the light. what is the student doing?

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.