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BIOL 1500
Marie Therese Rush

Unit 7: Photosynthesis and Global Warming The Greenhouse Effect Global warming- increases in Earth’s average temperature because of the release of carbon dioxide and greenhouse gases into the atmosphere -most warming observed in last century is attributable to human activities -caused by increases in concentrations of particular gasses in atmosphere, including water vapor, carbon dioxid(CO2)methane, and ozone Greenhouse effect- retention of heat by carbon dioxide and other greenhouse gases (increase surface temperature) -heat from the sun is absorbed in the atmosphere by water vapor, carbon dioxide and other greenhouse gasses and released back to earth - gases from the atmosphere trap long-wave radiation originating from the earth -without heat being trapped by atmospheric gases, our planet would plunge into extremely cold temperatures -greenhouse gasses is direct result of human activities, coal, oil, and natural gas combustion -most abundant gas emitted by combustion is carbon dioxide -- most important to control -atmosphere is primarily composed of nitrogen (78%) and oxygen (21%) but neither is considered a greenhouse gas because neither is very effective at trapping long-wave radiation from the earth Water, Heat, and Temperature -bodies of water absorb energy and help maintain stable temperatures on Earth -water can absorb large amounts of heat without undergoing rapid/drastic changes in temperature because heat must first be used to break hydrogen bonds between adjacent water molecule(high heat- absorbing capacity is a characteristic of water) Heat- total amount of energy associated with movement of atoms and molecules in a substance Temperature- measure of intensity of heat -water covers 70% of the earth’s surface and, therefore, has the ability to trap large amounts of heat. The water cycle: -water moves from the oceans and other surface waters to the atmosphere and back, with stops in living organisms, underground pools and soils, and ice caps and glaciers on land -most of the movement of water occurs outside living organisms Hydrogen bonding in water- hydrogen bonds break as they absorb heat and re-form as water releases heat The Carbon Cycle -carbon is mostly cycled due to biological activity -living organisms, volcanoes, deforestation and fossil fuel emissions produce CO 2 -plants, oceans, soil absorb CO 2 -carbon oxide you exhale enters the atmosphere, where it can absorb heat, these molecules can return to Earth’s surface where they can dissolve in water or be absorbed by plants Deforestation- the removal of forest lands, often to enable the development of agriculture Fossil fuels- nonrenewable resources made from buried remains of ancient plants transformed by heat and pressure into coal and oil(stored carbohydrates) -petroleum, coal, and natural gas (fossils because they are formed from buried remains of ancient plants and microorganisms and over millions of years, carbohydrates in these organisms were transformed by heat and pressure deep in Earth’s crust into highly concentrated energy sources) -used to power homes, vehicles, businesses -ice core data from Antarctica show Earth has gone through cycles of high carbon dioxide, however it is higher today than it has been in last 400 000 years Carbon dioxide sink- things that absorb carbon dioxide from the atmosphere (example- terrestrial photosynthesis by plans and the oceans) -together, they currently absorb about 50% of the CO tha2 humans emit into the atmosphere (percent is decreasing as we continue to lose forests through logging, development, and clearing for pasture) *both water and carbon cycle between animals, plants, soil, oceans, and the atmosphere Photosynthesis Photosynthesis- process by which plants and other microorganisms trap light energy from the sun and use it to convert carbon dioxide and water into sugar (transforms s
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