SNC1D BIOLOGY 9/24/2013. SUSTAINABLE ECOSYSTEMS L Cycling of Matter in Ecosystems (P.22-27) Cycling of Matter in Ecosystems

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1 SNC1D BIOLOGY SUSTAINABLE ECOSYSTEMS L Cycling of Matter in Ecosystems (P.22-27) Cycling of Matter in Ecosystems Energy flows through ecosystems when organisms consume other organisms. Unlike energy, which is converted into different forms but never returns to its source, matter is recycled through ecosystems. The same matter is transformed many times and is used over and over again. September 24, DBIOL - Cycling of Matter 1 Cycling of Matter in Ecosystems Like your body, an ecosystem undergoes continuous renewal to maintain its delicate balance. But renewal does not mean that new matter is made. All the water and nutrients of organisms are from particles that already exist in the environment. In biogeochemical cycles, particles are continuously consumed, rearranged, stored, and released. NOTE! The four main biogeochemical cycles are carbon, water, nitrogen, and phosphorus. September 24, DBIOL - Cycling of Matter 2 1

2 Cycling of Matter in Ecosystems BIOGEOCHEMICAL CYCLES movement of matter through the biotic and abiotic environments four main cycles L carbon, water, nitrogen, and phosphorus September 24, DBIOL - Cycling of Matter 3 September 24, DBIOL - Cycling of Matter 4 In the water cycle, liquid water evaporates and changes to water vapour. Next, the vapour condenses and forms ice crystals or water droplets. Then, the droplets collect to form clouds and fall to Earth as rain, hail, or snow. Water enters lakes, oceans, the soil, or groundwater, and the process continues. September 24, DBIOL - Cycling of Matter 5 2

3 NOTE! Water that is taken in by plant roots may be released from leaves in a process called transpiration. September 24, DBIOL - Cycling of Matter 6 WATER CYCLE(P.25) series of processes that moves water (in various states) through the environment PRACTICE 1. Draw a simplified version on the water cycle shown on the next slide. September 24, DBIOL - Cycling of Matter 7 September 24, DBIOL - Cycling of Matter 8 3

4 September 24, DBIOL - Cycling of Matter 9 Carbon moves between the abiotic and biotic parts of an ecosystem in the carbon cycle. Most of this exchange occurs between carbon dioxide (either in the atmosphere or dissolved in water) and photosynthesizing plants and micro-organisms. September 24, DBIOL - Cycling of Matter 10 While large quantities of carbon are cycled through the carbon cycle, most of Earth s carbon is stored in deposits such as coal, limestone, ocean sediments, the shells of marine animals, oil, and natural gas. These deposits, often referred to as carbon sinks, form when decomposed organisms are compressed over millions of years. September 24, DBIOL - Cycling of Matter 11 4

5 9/24/2013 CARBON CYCLE (P.27) series of processes that moves carbon through Earth s various spheres occurs mostly during photo-synthesis and cellular respiration most carbon is stored in carbon sinks such as: producers consumers sediments fossil fuels September 24, DBIOL - Cycling of Matter 12 NOTE! Humans can greatly affect the carbon cycle. For example, deforestation and burning fossil fuels releases stored carbon back into the atmosphere. The result is global climatic change. PRACTICE 2. How do human activities such as deforestation and burning fossil fuels affect the carbon cycle? What is the effect? they add carbon dioxide to the system and this is leading to a increased warming of the Earth (i.e. global warming) September 24, DBIOL - Cycling of Matter 13 September 24, DBIOL - Cycling of Matter 14 5

6 While there is lots of nitrogen in the atmosphere, nitrogen is not easy to acquire directly from the abiotic environment. Nitrogen enters and leaves the atmosphere through a complex biochemical pathway in the nitrogen cycle. September 24, DBIOL - Cycling of Matter 15 Most of the nitrogen used by living things is taken from the atmosphere by nitrogenfixing soil bacteria in a process called nitrogen fixation. These microorganisms convert nitrogen gas into a variety of nitrogen-containing compounds such as nitrates, nitrites, and ammonia. Lightning and UV light also fix small amounts of nitrogen. In addition, humans add nitrogen to the soil as fertilizer. September 24, DBIOL - Cycling of Matter 16 Once in the soil ecosystem, the nitrogen-rich compounds are available to producers. After the nitrogen is absorbed, it is passed from producer to consumer and on up the food chain until it eventually returns to the soil. Then the nitrites and nitrates are either recycled again by soil microorganisms or they are converted by denitrifying bacteria into nitrogen gas which then re-enters the atmosphere. September 24, DBIOL - Cycling of Matter 17 6

7 NITROGEN CYCLE(P.26) series of processes that moves nitrogen through Earth s various spheres involves: (a) the creation of ammonia, nitrites, and nitrates by decomposers, lightning or nitrogen-fixing bacteria in the soil and roots (b) denitrifying bacteria that release nitrogen gas back into atmosphere September 24, DBIOL - Cycling of Matter In what ways do human activities influence the: (a) water cycle? (b) carbon cycle? (c) nitrogen cycle? answers will vary September 24, DBIOL - Cycling of Matter Changes in the carbon cycle cause global temperatures to rise. How might this affect the water cycle? less ice and more liquid water leads to rising sea levels and more flooding, droughts, severe storms,... September 24, DBIOL - Cycling of Matter 20 7

8 3. What steps can people take to slow global climate change? answers will vary September 24, DBIOL - Cycling of Matter Plants need nitrogen to produce proteins and other important chemicals. Describe how nitrogen in the atmosphere makes its way into plants. decomposers, lighting & nitrogen fixing bacteria û ammonia û nitrifying bacteria û nitrites & nitrates (which plants use) September 24, DBIOL - Cycling of Matter How is the nitrogen in dead organisms released back into the soil? decomposers û ammonia û nitrifying bacteria û nitrites & nitrates (soil) September 24, DBIOL - Cycling of Matter 23 8

9 TEXTBOOK P.35 Q.4-6,11 WIKI(BIOLOGY) O... 1DBIOL - WS3 (Cycles of Matter) September 24, DBIOL - Cycling of Matter 24 9