he majority of Earth's atmosphere is nitrogen, N2. The percentage of nitrogen in Earth's atmosphere remains constant as prescrib
ed by the law of conservation of matter and because it is a reasonably non-reactive gas. Like carbon, nitrogen is cycled through Earth's spheres. However, nitrogen can be converted into forms usable by plants and animals, either by lightning or bacteria. Once converted to usable forms, nitrogen is able to cycle the rest of the way through the ecosystem. Much like carbon, the recycling of nitrogen through Earth's spheres relies heavily on what type of organism? A) autotrophs B) decomposers C) parasites D) producers
Decomposers such as Cellulomonas bacteria convert the nitrogen in the dead matter into ammonia while Nitrosomonas bacteria convert the ammonia into nitrites that are absorbed by plants as nutrients. In addition, nitrobacters convert the nitrites to nitrates also absorbed by plants.
Gravity is the force by which a planet or other body draws objects toward its center. The force of gravity keeps all of the planets in orbit around the sun.
