Human epithelium contains a layer of cube-shaped cells. If the length, height, and width of such a cell is 1 micrometer (um), what is the surface area of its
cell membrane?
O A. 6 pm
B. 3 um
O C. 6 um?
O D. 3 um

Competition occurs between species when

Which phrase is the best summary of the model shown? a. the transfer of the sun's energy through trophic levels b. a series of aerobic and anaerobic reactions c. a transformation of light energy into chemical energy d. the breakdown of food molecules

Most of the carbon on earth is stored in the form of