Biology questions, please help?!!?

explain how carbon cycles through a desert ecosystem by tracing a molecule of carbon dioxide fro the atmosphere, through several trophic levels(up to tertiary, and then back into the atmosphere to complete the carbon cycle. identify three ways carbon dioxide can return to tge atmosphere, the organic and inorganic forms of carbon, and what happens to the amount of energy in each trophic level of the desert ecosystem as energy pes through. explain how our reliance on fossil fuels such as petroleum and natural gas, influences the carbon cycle.