Renewable resources are solar energy, wind energy, geothermal energy, biofuels, cultivated plants, biomass, air, water and soil. In contrast, non-renewable resources are those that are available to us in limited quantities, or those that are renewed so slowly that the rate at which they are consumed is too fast.
The carbon cycle. Although it's not specific, it talks about combustion or respiration. The reason I chose the carbon cycle, is because nitrogen DOES appear in photosynthesis, but you were strictly talking about carbohydrates.
