What is an animal that kills and eats another animal?

According to the cell theory, which describes cells? a. all organisms are composed of multiple cells. b. all cells have the same structure and function. c. cells are found in everything on earth. d. living organisms are not created spontaneously

When listening the levels of orginization in orginisims from the smallest to most complex , which level is just below organs in complexity

Several billion years ago which gas was the least prevailant in the atmosphere