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35 Cards in this Set
- Front
- Back
Phosphorus Cycle: Basic Facts
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- Phosphorus is a key part of DNA and energy storage molecules, such as ATP, in cells
- Plants require DNA and ATP - Because of low phosphorus levels in soil, it becomes a limiting factor for plant growth on land unless it is added directly to soil as fertilizer |
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Phosphorus: Human Activities and Their Effects
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- Humans remove large amounts of phosphorus to make fertilizer
- Phosphorus levels are reduced in tropical forests as they are cleared - Humans add excess phosphates to aquatic systems by runoff and sewage treatment plants, causing eutrophication (algal blooms) |
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More Phosphorus!
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- Movement of phosphorus goes through the lithosphere, hydrosphere, and biosphere (not atmosphere because it is only a solid)
- Found in water, soil, and living organisms - Makes up part of RNA/DNA molecules that store energy - Building block for bones and teeth - Guano (bird pooooooo) - Could run out because fertilizer runs into the ocean and then the phosphorus stays there for millions of years |
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Sulfur Cycle: Basic Facts
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- Sulfur Dioxide: colorless, odorless gas
- Circulates through the biosphere - Stored in underground rocks and minerals and deep under ocean sediments |
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Sulfur enters through natural sources
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- Hydrogen Sulfide enters through volcanic eruptions, bacterial processes, flooded swamps, and other sources
- Sulfate salts come from sea spray, dust storms, and forest fires --> Absorbed through plant roots |
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Natural Sources of Sulfur: Marine Algae
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- Produce large amounts of volatile dimethyl sulfide
--> Tiny drops serve as nuclei for condensation of water --> Change in emissions can effect cloud cover and climate --> Converted into sulfur dioxide; becomes a component of acid rain |
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Human Sources of Sulfur
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- SO2 added to the atmosphere by burning fossil fuels
- Also convert sulfur-containing metallic mineral ores into free metals such as copper, lead, and zinc |
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Water Cycle
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- Located in the hydrosphere
- Continuous movement of water in all states on Earth - Controlled by the sun - Evaporation, evapotranspiration, precipitation, runoff, infiltration, condensation, sublimation (snow or ice to water vapor) - Human Water Cycle: take in water, nutrition absorbed by organs, excreted |
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Human Effects on Water Cycle
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- Use water faster than can be replenished
- Clearing land increases flooding because runoff has nowhere to go - Increased global warming because water cycle speeds up and there is more water vapor (greenhouse gas) |
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Nitrogen Cycle (Steps 1-3)
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1. Nitrogen Fixation: gaseous nitrogen to ammonia (NH3)
--> Cyanobacteria --> Rhizobium 2. Nitrification: 2 step process --> Nitrites (NO2-) to Nitrates (NO3-) --> Specialized aerobic bacteria 3. Assimilation: plant roots absorb inorganic ammonia, ammonium ions, and nitrate ions --> Used to make proteins, amino acids, and DNA |
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Nitrogen Cycle (Steps 4-5)
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4. Ammonification: occurs during decomposition by bacteria; convert organic compounds with nitrogen to make:
--> Ammonia (NH3) --> Water-soluble salt containing Ammonium ions (NH4+) 5. Dentrification: mostly anaerobic bacteria --> Convert NH3 and NH4+ back into N2 and N2O; both gases released into atmosphere |
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Inorganic Commercial Fertilizers (NPK: Nitrogen, Phosphorus, Potassium) --> Pros
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- Makes soil nutrient rich
- Increases crop yields - Easily obtained transport |
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Inorganic Commercial Fertilizers: Cons
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- Runoff--> Eutrophication
- Some nutrients are in limited supplies - Does not add humus - Does not add all nutrients that may be needed |
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Carbon Cycle: Basic Facts
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- Carbon Cycle: the movement of carbon in its many forms between the biosphere, atmosphere, oceans, and geosphere
- Carbon exists in the nonliving environment as carbon dioxide, carbonate rocks, coal deposits, and dead organic matter - Carbon is used in the biotic world by photoautotrophs (plants & algae) that convert CO2 to organic matter as well as chemoautotrophs (bacteria & archaea) |
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Why is carbon important to ecosystems?
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- Carbon is essential to ecosystems for photosynthesis, the production of food from light
- Marine organisms also use dissolved CO2 molecules for shells and skeletons - In decaying plant matter, carbon creates fossil fuels |
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Missing Carbon
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- If too much carbon dioxide is in the carbon cycle, the temperature will increase; if too much is removed by the carbon cycle, the atmosphere cools
- This determines the types of life that can survive in various environments - Currently the increase of CO2 is only half the expected amount from burning fossil fuels - Increased CO2 levels increase photoautotroph production - The evidence of this phenomenon includes increased growth of forests, increased phytoplankton, and uptake by desert soils |
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Carbon Cycle: Effects of Human Activity
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- When CO2 is in the form of fossil fuels, it is not part of the carbon cycle
- Humans add carbon to the cycle by using fossil fuels and by cutting down CO2-absorbing trees & plants |
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Evolution
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- Chemical Evolution --> 1 billion years
- Biological Evolution --> 3.7 billion years - Stanley Miller: experiments involving chemical evolution --> Simulated Earth's early atmosphere |
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Evolutionary Tree
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- Bacteria before plants
- Organelles (chloroplasts, mitochondria) existed before Eukaryotes and have DNA --> Endosymbiotic relationship between organelles and cell |
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The World
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- Pangaea (225 million years ago) --> Plate tectonics separated the land and where species lived
- Our current world formed 65 million years ago - Humans have existed for a very small period of time ("2 seconds before midnight') |
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Mutations
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- Good or bad change in DNA
- Natural Selection ("Survival of the Fittest"): Ability to survive environmental change and pass on one's genes to fertile offspring --> Adaptive Traits |
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Coevolution
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Species evolve together to the benefit of both species
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Rapid Change
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Hybridization --> two different species reproduce (i.e. mules)
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Ecological Niches
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Role of the organism in the ecosystem
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Fundamental Niche
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Full range of chemical, biological, and physical resources available to an organism
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Realized Niche
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The part of the fundamental niche the organism occupies
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Specialist Species
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Narrow niche
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Generalist Species
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Broad niche
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Stabilizing Selection
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Favors intermediate populations
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Disruptive Selection
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Favors extreme forms of the population
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Speciation
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Population splits up and different environmental conditions lead to different selective pressures and evolution into two different species
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Geographic Isolation
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Leads to reproductive isolation --> Allopatric Speciation
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Background Extinction
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Occurs because environmental conditions change
--> Estimated 1 to 5 species per year goes extinct per 1 million species |
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Mass Extinction
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Occurs when extinction rates exceed background extinction rates
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Figure 4-14 (p.95)
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- Recombinant DNA: Genetic material of two organisms
- Transgenic Plants: Plants with new traits |