What first apperead on earth during precambrian time

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

Antoine manages a number of apartment buildings that use natural gas for heating, cooking, and laundry. the scatter plot shows the correlation between the outside air temperature and antoine's natural gas bill. which type of correlation does the plot illustrate?

All ova contain sex chromosomes corresponding to: x y xx xy