for crossing over to occur, homologous chromosomes must align precisely early in prophase i so that nonsister chromatids can exchange corresponding segments of dna.

the titanic would be the correct answer

above statement is not a true statement about the open ocean because the open ocean has low levels of nutrients. most of the photosynthetic activity on earth occurs in the open ocean within the photic zone. organisms in the deep ocean are exposed to frigid temperatures and total darkness but it does not begin at the low-tide mark.