What causes the base pairs of dna to break apart?

In what for do plants utilize nitrogen? why do they need nitrogen?

In "the man in the water," what was the remarkable occurrence that rosenblatt reported?

During a fierce storm a large number of tall trees on an island are uprooted by the wind and die. most of the trees on the island are now short trees and produce seeds that grow into short trees. what concept is shown in this example? question 5 options: natural selection artificial selection genetic engineering gene splicing