Exam 1 Study Guide: Ecosystems II - Cycling of Elements/Nutrients Flashcards
Describe the movement of water in the hydrological cycle.
Evaporation, transpiration, condensation, precipitation, infiltration, runoff, groundwater flow, and sublimation
Where is most of the water on Earth found? Recognize the small percentage of freshwater relative to other sources.
Oceans: 96.5% saltwater
Groundwater: 30.1% freshwater
Ice caps + glaciers: 68.7% freshwater
surface water: 0.3% freshwater
What drives the hydrological cycle?
Solar energy for evaporation and transpiration. Gravity for precipitation, runoff and groundwater flow.
What are Anthropogenic effects on the hydrological cycle?
Land use like deforestation and urbanization. Water management like dams and groundwater extraction. Climate change and pollution too.
Describe the movement of carbon in the carbon cycle.
Photosynthesis, respiration, consumption, decomposition, fossil fuel formation, and combustion.
Distinguish carbon sinks from sources. Give examples for each.
- Carbon Sinks: Absorb more carbon than they release. Examples: Forests, oceans, soils.
- Carbon Sources: Release more carbon than they absorb. Examples: Burning fossil fuels, deforestation, respiration.
What are two fundamental processes associated with the carbon cycle? How might increasing atmospheric carbon dioxide change the rate of these processes?
Photosynthesis and respiration. Increased CO2 could increase photosynthesis initially and increase respiration from increased temp.
Describe the movement of nitrogen in the nitrogen cycle.
Nitrogen fixation, nitrification, assimilation, consumption, ammonification, dentrification
Why is nitrogen important to life? Consider the building blocks for phenotypes
It’s a key component of proteins which are important for building tissues. And nucleic acids (DNA + RNA).
Distinguish between the different types of nitrogen. Focus on where different forms of nitrogen are found.
N2: atmospheric, makes up 78% of atmosphere, unusable by most organisms directly
Ammonia(NH3)/Ammonium(NH4+): found in soil, produced by nitrogen fixation, usable by plants
Nitrites(NO2-): found in soil, product of nitrification
Nitrates(NO3-): found in soil, product of nitrification, primary form of nitrogen taken by plants
Organic nitrogen: in living organisms and decaying matter
Define denitrification, assimilation, mineralization, and nitrification
Denitrification : some bacterial converts nitrates back to N2 releasing it to the atmosphere
Assimilation: plants take up nitrates/ammonium and incorporate nitrogen into organic materials.
Mineralization: organic matter is broken down by decomposers and convert it back into ammonium - available for plants to use.
Nitrification: ammonia/ammonium in converted to nitrites and then nitrates - usable by plants
Where are significant nitrogen pools?
Atmosphere - nitrogen gas
Soil - organic matter, ammonium, nitrates, nitrites
Oceans - dissolved N2
Living organism
Describe the movement of phosphorus in the phosphorus ‘cycle.
released through weathering, uptake in the soil, consumption, decomposition, sedimentation. No atmospheric part
Why is phosphorus important to life?
Key components of DNA, RNA, ATP, phospholipids
What are natural sources of phosphorus? Anthropogenic sources?
Natural: weathering of rocks and volcanic activity
Anthropogenic: fertilizers, sewage, industrial waste, agricultural runoff
What are significant phosphorus pools?
Rocks and sediments, soil, oceans, living organisms
Explain eutrophication and ‘dead zones.’
Eutrophication: excess nutrients enter water bodies causing algal blooms.
Dead Zones: when algae dies their decomposition consumes large amounts of oxygen which creates dead zones where aquatic life cannot live.
Compare and contrast nutrient cycling in terrestrial and aquatic ecosystems. What processes help nutrients move in ecosystems?
Similarities: Both rely on decomposition to recycle nutrients from organic matter back to usable forms. Both involve uptake by primary producers and transfer through food webs.
Differences: nutrient forms, terrestrial cycles involve more vertical movement, aquatic has horizontal. Terrestrial system are better at retaining nutrients. Terrestrial systems have plants with mostly roots, aquatic systems have diverse primary producers.
