Transcript File
Chapter 3.3 Cycles of matter RECYCLING in the BIOSPHERE Unlike the one-way flow of energy (food pyramid), matter is recycled within and between ecosystems. Biogeochemical cycle-process in which elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another. 1. WATER CYCLE- water moves between the ocean, land and air. Water when enters the atmosphere, it enters as a gas or vapor through the process of evaporation and transpiration. • Evaporation-process by which water changes from a liquid into an atmospheric gas • Transpiration-loss of water from a plant through its leaves • When the water vapor changes into tiny droplets through the process of condensation, the tiny droplets change into drops causing precipitation in the form of: rain, sleet, snow or hail. When the water arrives at the land, some of the water enters rivers or streams that lead to an ocean or lake. Some of the water will enter the soil and become ground water. Plants will absorb water from the ground and the water cycle will repeat. Nutrient Cycling 2. NUTRIENT CYCLES: every organism needs nutrients to grow and carry out essential live processes. Like water, nutrients are passed between organisms and the environment through biogeochemical cycles. • Nutrient- chemical substance that an organism requires to live a. CARBON CYCLE-in the atmosphere, C02 is present as a gas. It is released to the atmosphere by the volcanic activity, by respiration, by human activities such as burning fossils fuels, and by the decomposition of organic matter. Plants take in CO2 and use water to convert them into sugar (carbohydrates) and O2. The carbohydrates are then transferred to animals and other consumers. In the ocean, carbon is found, along with calcium and oxygen, in calcium carbonate, which is formed by many marine organisms. Calcium carbonate can chemically formed in some marine environments. It can be deposited as carbonate rocks and in the bones and shells of organisms. Eventually, these compounds break down and return to the atmosphere. b. NITROGEN CYCLE- Bacteria in soil and on plant roots convert atmospheric nitrogen to ammonia. Other soil bacteria then convert the ammonia to nitrates and nitrites, which are taken in by producers. Decomposers convert the nitrogen in animal wastes and dead organisms into ammonia, nitrates and nitrites, which are then available to plants. Soil bacteria break down the nitrates and nitrites into nitrogen gas which is released into the atmosphere. • Nitrogen fixation- process of converting nitrogen gas into ammonia • Denitrification- conversion of nitrates into nitrogen gas c. PHOSPHORUS CYCLE-is very important to living organisms because it is a part of DNA and RNA. Unlike carbon, oxygen, or nitrogen, phosphorus does not enter the atmosphere. It usually remains on land in rock and soil minerals, and in ocean sediments. There, phosphorus exists in the form of inorganic phosphate. As the rocks and sediments wear down, phosphate is released. On land, some of it goes into rivers and streams where it dissolves. The phosphate makes its way to the oceans, where it is used by marine organisms. Some of phosphate stays on land and cycles between organisms and the soil. When plants absorb phosphate form the soil or from water, the plants bind the phosphate into organic compounds. Organic phosphate moves through the food web, from producers to consumers and to the ecosystem. NUTRIENT LIMITATION Primary productivity-rate at which organic matter is created by producers in an ecosystem. One factor that controls the primary productivity of an ecosystem is the amount of available nutrient. If the nutrient is in a short supply, it will limit an organisms’ growth. Limiting nutrient- is a single nutrient that either is scarce or cycles very slowly, limiting the growth of organisms in an ecosystem. In the ocean and lakes, nitrogen is the limiting nutrient. In some areas of ocean, silica or iron is the limiting nutrient. In streams, lakes and freshwater, phosphorus is the limiting nutrient. Algal bloom-is an immediate increase in the amount of algae and other producers that results from a large input of a limiting nutrient. Example: runoff from heavily fertilized fields results in the immediate increase in the amount of algae and other producers. QUESTIONS: 1. How does the way that matter flows through an ecosystem differ from the way that energy flows? 2. Why do living things need nutrients? 3. Explain how a nutrient can be a limiting factor in an ecosystem. 4. Critical thinking: based on your knowledge of the carbon cycle, what do you think might happen if vast areas of forest are cleared?