Astronomers use the distancebetween Earth and sun, which is 93 million miles, as a new unit of measure called the Astronomical Unit. It is defined to be exactly 1.00 for the Earth-Sun orbit distance, and we call this distance 1.00 AUs.
<span>Two main characteristics that distinguish autotrophs from heterotrophs are:
A~ Autotrophs produce their own food by either chemosynthesis or photosynthesis. Heterotrophs do not produce their own food. Heterotrophs obtain their food by consuming autotrophs or heterotrophs.
B~ Autotrophs are at the primary level in a food chain and Heterotrophs are at the secondary level or tertiary level in a food chain.</span>
Nitrogen fixation- atmospheric nitrogen is assimilated into organic compounds especially by certain microorganisms as part of the nitrogen cycle.
Burning. Carbon moves from fossil fuels to the atmosphere when fuels are burned.
