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Plants play a crucial role in the carbon cycle because they a. do not release carbon dioxide during cellular respiration. b. allow carbon to enter an ecosystem through photosynthesis. c. have special bacteria that live in their root systems. d. are chemically converted into fossil fuels when burned. Which item is a carbon sink and not part of the carbon cycle? a. carbon in the atmosphere in the form of carbon dioxide b. consumers breaking down carbohydrates into carbon dioxide during respiration c. carbon found within limestone rocks d. carbon dioxide being converted into carbohydrates during photosynthesis Which of the following is not a true statement about cellular respiration? a. It is essentially photosynthesis in reverse. b. Oxygen is one of the primary reactants. c. It produces energy for organisms to use. d. Sugar molecules are its primary products. We use but don’t always reuse. We recycle paper, metals, water, etc. We recycle almost 50% of paper in U.S. – about 42 million tons. But ecosystems constantly re-use carbon, nitrogen and phosphorus. All life is based on the element CARBON. Carbon is the major chemical constituent of most organic matter, from fossil fuels to the complex molecules (DNA and RNA) that control genetic reproduction in organisms. Carbon Cycle Carbon is found in protein, fats, and sugars/carbohydrates. Carbon cycles between the atmosphere, land, water, and organisms. Carbon is stored on our planet in the following major sinks: (1) as organic molecules in living and dead organisms found in the biosphere; (2) as the gas carbon dioxide in the atmosphere; (3) as organic matter in soils; (4) in the lithosphere as fossil fuels and sedimentary rock deposits such as limestone, dolomite and chalk; and (5) in the oceans as dissolved atmospheric carbon dioxide and as calcium carbonate shells in marine organisms. Carbon Cycle Short-term carbon cycle Like most everything it starts with producers: Plants produce carbohydrates (glucose) by photosynthesis. Consumers eat the plants. Consumers break down glucose by cellular respiration. Energy is released back into the atmosphere. Short-term carbon cycle Carbon is released from ecosystems as carbon dioxide gas by the process of respiration. Respiration takes place in both plants and animals and involves the breakdown of carbon-based organic molecules into carbon dioxide gas and some other compound by products. The detritus food chain contains a number of organisms whose primary ecological role is the decomposition of organic matter into its abiotic components. Long-term Carbon Cycle cont… Unused carbohydrates are stored as fat and oil. Carbon returns to the soil after organism’s death. Over time this turns into coal, oil, natural gas. Fossil fuels How Humans Affect the Carbon Cycle http://www.youtube.com/watch?v=c40jebr9jbg Burning fossil fuels releases 6 billion tons CO2 into the atmosphere. Trees can remove CO2 from the atmosphere. This can contribute to global warming. Long-term Carbon Cycle When consumers eat, some carbon is stored. carbonates = bones and shells Over millions of years carbonates turn into limestone. largest reservoir/storage of carbon How Humans Affect the Carbon Cycle Since the Industrial Revolution, humans have increased the quantity of carbon dioxide found in the Earth's atmosphere and oceans by over 30%. Major sources of this gas due to human activities include fossil fuel combustion and deforestation and habitat destruction. Emissions from fossil fuels account for about 65% of the additional carbon dioxide currently found in the Earth's atmosphere. The other 35% is derived from deforestation and the conversion of natural ecosystems into agricultural systems. Which item is a carbon sink and not part of the carbon cycle? a. carbon in the atmosphere in the form of carbon dioxide b. consumers breaking down carbohydrates into carbon dioxide during respiration c. carbon found within limestone rocks d. carbon dioxide being converted into carbohydrates during photosynthesis The Nitrogen Cycle Organisms need nitrogen to build proteins that are needed to build cells. Nitrogen makes up 78% of the atmosphere (about one million times more than the total nitrogen contained in living organisms), but most organisms cannot use it in this form. Other major stores of nitrogen include organic matter in soil and the oceans. In most ecosystems nitrogen is primarily stored in living and dead organic matter. Nitrogen Cycle cont… Nitrogen is cycled between the atmosphere, bacteria, and other organisms. Bacteria live in the roots of legumes (beans, peas, and clover) in nodules. In exchange for some nitrogen, the bacteria receive carbohydrates from the plants. Some bacteria live in the soil and put nitrogen in the soil. Plants use nitrogen in soil, consumers eat plants, and so on… The Nitrogen Cycle The Nitrogen Cycle Almost all of the nitrogen found in any terrestrial ecosystem originally came from the atmosphere. Significant amounts enter the soil in rainfall or through the effects of lightning. The majority is biochemically fixed within the soil by specialized micro-organisms like bacteria, actinomycetes, and cyanobacteria. The Nitrogen Cycle Decomposers in the Nitrogen Cycle After bacteria convert nitrogen, plants use the nitrogen and consumers eat plants. Decomposers help return nitrogen back to the atmosphere by breaking down urine, dung, leaves, dead plants and animals. Phosphorus Cycle Needed for bone and teeth formation Plants get phosphorus from soil and water; consumers get phosphorus from plants. Moves from environment to organism to environment; usually not in the atmosphere. The Phosphorus Cycle Phosphorus Cycle cont… Phosphorus enters the soil when rock erodes. Returns through waste and decomposing organisms. Some phosphates get washed out to the ocean and deposit on the ocean floor. Fertilizers Contain phosphorus and nitrogen Application of fertilizers to crops has caused increased rates of nitrate leaching into groundwater. Additional nitrogen entering the groundwater system eventually flows into streams, rivers, lakes, and estuaries. In these systems, the added nitrogen can lead to eutrophication. Algae blooms Last Problem When coal, wood, or oil are burned, nitric oxide is released. Nitric oxide combines with oxygen and water vapor to make nitric acid/acid rain.