NAEP Science Grade 12

Correct Response: D. All sources of genetic variation rely on an initial change or mutation to the genetic code and mutations can occur both in sexually and asexually reproducing organisms. Although independent assortment of homologous chromosomes (A) and recombination (B) of chromosomes resulting from crossing over events (C) during meiosis are sources of genetic variation in sexually reproducing organisms, they will not result in genetic variation if the genetic material is identical to begin with.