The heat in earth's interior comes from which of the following sources? a. the mantle b. the sun c. breakdown of unstable elements d. meteorite impacts

When is a hurricane considered to have made landfall? a. when at least one inch of rain occurs b. when the eye reaches the land mass c. when the outer wind bands make landfall d. when it moves inland from the coast

Which of the following occurs most often in a population when genetic variation and overproduction are present? some organisms have a lower reproductive success than others. some organisms have a higher reproductive success than others. some organisms have no reproductive success. some organisms do not have genetic variation.

Why has two different alleles for the same trait?