In the graph, "ppm" stands for parts per million. A concentration of one ppm is a ratio of one part to one million parts. Concentrations can also be expressed as a percentage. Why do you believe scientists choose ppm over percentage in some cases?

Which statement is true for bacteria a. bacteria have complex internal structures b. all bacteria are spiral in shape c. all bacteria cause disease in animals d. bacteria break down some foods

There are fewer than 100 naturally occurring elements in the universe, but there are millions of different unified substances. explain how this can be true.

Select the correct answer from each drop-down menu the images show fossils of a modern bird and two extinct organisms (a tyrannosaurus rex and an archaeopteryx). based on the structure of the three organisms, it can be concluded that the archaeopteryx and bird have wings, while dinosaurs have limhe se it can be concluded that