Biol 112 Nov. 28- 30 (C)

Biol 112 Nov. 28- 30 (C) - 1 Nutrients and the elemental...

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Unformatted text preview: 1 Nutrients and the elemental cycles. Cells are made of Carbon, Nitrogen, Phosphorus, Sulfur, Hydrogen and Oxygen. These are the “major nutrients”. Because cells live, grow, die, and decay, the elements that make up cells are transformed through what are called elemental cycles. We will focus on Carbon, Nitrogen and Sulfur. Approximate composition of Earth’s crust Oxygen makes up about 47%. Silicon makes up 28%. • Carbon = 0.03% • Nitrogen = 0.005% • Sulfur = 0.05% • Phosphorus = 0.12% Most of the oxygen is linked to water, calcium and silicates. The Global Carbon Cycle (values shown in gigatons of carbon per year) THE GLOBAL CARBON CYCLE Al values in gigatons of carbon per year Atmosphere: 778 (during 1990s) Net uptake via photosynthe sis by plants: 3.0 Net uptake via photosynthesis, chemical processes: 1.5 Land-use change (primarily deforestation): 1.6 Fossil-fuel use: 6.3 The ocean is the largest carbon source. Atmospheric carbon is small – carbon moves in and out through organisms. Fig 54.14 Biological Sciences Organisms, chemical processes in ocean: 40,000 Rivers (erosion): 0.8 Organisms, soil, litter, peat: 2190 Terrestrial ecosystems Human-induced changes Carbon Cycling Carbon is an essential component of life and is cycled through living and decaying organisms, the atmosphere, water, rocks and soil. 1 Photosynthesis conversion of CO to CHO 1. Photosynthesis – conversion of CO 2 to CHO (carbohydrates) for chemical energy. 2. Cellular respiration – CHO converted to energy and CO 2 . O 2 converted to water. 3. Decomposition of organic matter to CO 2 . Carbon Cycling 4. Ocean – dissolved CO 2 stored. Marine organisms store carbon as carbonate (CO 3 2- ) in their shells which forms sedimentary rock in the oceans. 5 Volcanic eruptions magma contains dissolved gases 5. Volcanic eruptions – magma contains dissolved gases. Most abundant is water vapour, CO 2 and SO 2 (sulfur dioxide) 6. Forest fires – release CO 2 Changes in the global carbon cycle Global changes in atmospheric CO 2 over time Due to:-burning of fossil fuels-deforestation CO 2 is a green house gas! 2 Carbon Cycle Note the aerobic v.s. anaerobic processes CHO CO 2 Aerobic Anaerobic CH 4 CHO CHO The yellow highlighted arrow is a process is a(n): A. Oxidation Carbon Flux CHO Anaerobic B. Reduction C. Depends on what the other reactant is. CHO CO 2 Aerobic Anaerobic CH 4 CHO CHO The yellow highlighted arrow is a process is a(n): A. Oxidation Carbon flux CHO Anaerobic B. Reduction C. Depends on what the other reactant is. Photosynthesis phototrophs Energy: light C from CO 2 Some organics Energy: oxidizing inorganic molecules C from CO 2 chemolithotrophs Energy: oxidizing organic molecules chemoheterotrophs C from organic C Alternate electron donors and acceptors Table 28.5 Alternate electron donors and acceptors Table 28.5 3 CHO CO 2 Aerobic Anaerobic CH 4 CHO CHO The yellow highlighted arrow is a process that is performed by: 1. Chemoheterotrophs respiring aerobically...
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This note was uploaded on 01/15/2012 for the course BIOL 112 taught by Professor Benbasat during the Winter '04 term at UBC.

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Biol 112 Nov. 28- 30 (C) - 1 Nutrients and the elemental...

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