Why is genetic variation necessary for natural selection to occur?

The energy available as a result of the motion of a body is called energy. -potential -gravitational -kinetic -chemical

The reactions that occur in the ribosome, where amino acids are combined to form proteins are anabolic or catabolic?

Which is not a likely outcome after extensive irrigation of dry farmland? useless, unproductive soil salinization of the soil depletion of groundwater nutrient-rich soil