What can i do to not fall asleep in class?

Which is one example of a phenotypic change that is not genetic

The table below shows the elements that mainly comprise each of the four layers of earth: elements in layers layer main elements crust oxygen, silicon mantle iron, magnesium outer core iron, nickel inner core iron which of these elements make up the layer that is 0.2 to 1.1 percent of earth's total diameter?

When you aware sick your body produces more leukocytes. briefly describe where the leukocyte are formed, how they are transported, and where they may be stored.