Vocabulary: Carbon Cycle Vocabulary  Atmosphere – the gases that surround a planet. o Earth’s atmosphere consists of nitrogen (78%), oxygen (21%), argon (1%), and smaller amounts of other gases, including carbon dioxide and methane.  Biomass – the total mass of a group of living things. o The animal species with the greatest biomass may be Antarctic krill, a small, shrimp-like organism.  The biomass of Antarctic krill is about 500 million metric tons. (One metric ton is equal to 1,000 kg, or