In the lungs, what can affect the suface area

Which element is used in photosynthesis found in atmosphere and fixed by bacteria?

Students in biology are studying the macromolecules of life. they used a calorimeter to determine the calories in various types of food. once the lab was completed, the students ate the left over food samples. monica commented that in just 6 or 7 "chews" of the saltine, it was gone; nothing but a sticky paste in her mouth. elaborate on what happened chemically while chewing the saltine. include the macromolecules present.

The distant ancestors of tigers may have had bodies without stripes. use the theory of natural selection to explain how tigers may have evolved to have stripes.