Why does abiotic element arrive first in primary

In the ocean why are the greatest amount of primary producers found in the epipelagic zone and how does that affect biodiversity

Anormal strand of dna is shown below, followed by the same strand of dna after mutations have occurred.

On a spring day, a middle-latitude city (about 40? north latitude) has a surface (sea-level) temperature of 10 ? c. if vertical soundings reveal a nearly constant environmental lapse rate of 6.5 ? c per kilometer and a temperature at the tropopause of –55 ? c, what is the height of the tropopause?