The Carbon Cycle – Answers 1. Macronutrients are used by organisms in large quantities while micronutrients are used only in trace quantities. 2. a. Primary producers incorporate material substances into organic compounds (e.g. plants) b. Secondary consumers eat primary consumers (e.g. lion) c. Decomposers are small animals and micro organisms that subsist on decaying matter such as fallen leaves, dead bodies, and animal waste (e.g. earthworms, mites, centipedes, insects, crustaceans) 3. Most of the Earth’s carbon is located in the atmosphere, which is Earth’s major reservoir of carbon, in the form carbon dioxide. 4. Carbon enters the biotic part of the ecosystem through photosynthesis. 5. Plants of the forest take the carbon in carbon dioxide and fix it in organic compounds such as glucose, starch, cellulose, and other carbohydrates. 6. Carbon dioxide is returned to the atmosphere through respiration in plants. 7. A primary producer is a plant. In the course of plant consumption, carbon passes into primary consumers, animals. 8. When primary and secondary consumers die, their organic matter enters the soil through the process of decay. It is broken down by the decomposers, or detritus feeders. 9. Detritus feeders contribute carbon to the atmosphere through respiration. 10. A fossil fuel is carbon-containing organic material that has been transformed into coal, oil, and natural gas through high pressure and temperature. 11. Carbon gets in the oceans through carbon dioxide dissolving from the air.