Nitrogen fixation is the conversion of nitrogen gas into ammonia. Please select TWO answers of how this can occur: A)air on top of the top layer of soil comes in contact with particular types of nitrogen-fixing bacteria

B)overflow of water within the soil

C)man-made fertilizers on farm fields exceed natural nitrogen levels in the soil and kill all the bacteria

D) by the intense energy of a lightening strike

Autotrophs a. consume their food to get energy b. may use photosynthesis to gain energy c. are also called consumers d. cannot use solar energy

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.

Which of the following was not a major animal on land during the carboniferous period? amphibians insects both a and b none of the above