Adds genetic variation, which is essential for evolution

Johnny rode his bike to a friend's house 4 blocks down the street in his neighborhood. he immediately rode back home once he realized his friend was not able to play. what was his displacement for the total bike ride? how did you determine this? what could we use as a reference point to determine he was in motion during his bike ride? why can you use it as a reference point

What is usually (but not always) related to the metabolic processes of living organisms in its organic form?

Eutrophication caused by human nutrient pollution.