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Questions and Answers
Which of the following correctly describes a feature of the nitrogen biogeochemical flow?
What is the main form in which phosphorus is commonly found?
Which type of feedback amplifies the initial input, continuing in one direction?
What phenomenon serves as an example of a positive feedback loop in climate change?
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In the short-term carbon cycle, which process returns carbon dioxide back to the atmosphere?
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Which component acts as the largest reservoir for carbon?
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How does weathering of rocks influence atmospheric carbon dioxide levels?
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What role do keystone species play in ecosystems?
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What is the primary role of nitrogen-fixing bacteria in the nitrogen cycle?
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Which process directly results in the atmospheric nitrogen being converted into nitrate in the nitrogen cycle?
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In which environment do methanobacterium typically release methane gas?
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What significant event is associated with the increase of oxygen in Earth's atmosphere 2.3 billion years ago?
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Which of the following reservoirs holds the largest percentage of nitrogen on Earth?
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Which of the following is a method through which nitrogen is fixed naturally, aside from bacteria?
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What effect does anoxia have on the carbon cycle?
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Which of the following compounds can plants directly access as nitrogen sources?
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Which gas contributes the least to the Greenhouse Effect due to its properties?
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What effect does longwave radiation have on carbon dioxide?
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Which method of heat transmission involves the movement of warm air to cooler regions?
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How does the uplift of the Himalayas affect the carbon cycle?
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What significant shift in climate conditions happened over the last 50 million years?
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Which gas is noted for having nine different types of vibrations, contributing to its impact on the greenhouse effect?
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What is the role of chemical weathering in the long-term carbon cycle?
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Which of the following is NOT a method by which heat is transmitted?
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Study Notes
Planetary Boundaries
- Nitrogen is the biogeochemical flow that has been surpassed in planetary boundaries
Phosphorus Cycle
- Important for freshwater systems
- Mostly found in rocks as phosphates
Feedback
- Negative feedback counters initial input (e.g. body temperature regulation through sweating and shivering)
- Positive feedback amplifies initial input (example: melting permafrost releasing methane and CO2, further increasing temperatures)
- Keystone species are crucial for the health of an ecosystem
Carbon Cycle
- Carbon has 4 electrons in its outer shell allowing for easy bonding, especially with itself
- Carbon forms chains, creating glucose, and is found in rocks and shells as calcium carbonate
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Short-term carbon cycle:
- CO2 in the atmosphere is absorbed by photosynthesis and released through cellular respiration, decomposition, and animal waste
- Human activities have moved coal, a long-term carbon store, into the short-term cycle
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Long-term carbon cycle:
- Carbon is stored in sedimentary rocks as the largest reservoir
- Weathering of rocks removes carbon dioxide from the atmosphere
- Keeling Curve: Shows seasonal variations in CO2 concentrations
Anoxia (No Oxygen)
- Leads to carbon sequestration due to lack of decomposition
- Photosynthesis by organisms like duckweeds removed CO2 from the atmosphere, resulting in an 80% drop
Ultraviolet Radiation
- Higher energy radiation is more damaging
- UV-C is the most damaging, but the Ozone layer protects us
- The Ozone layer was created by photosynthesis as a byproduct
- Great Oxygenation Event (2.3 Billion Years Ago) initiated the formation of the Ozone
Key Events in Earth's History
- First producers, cyanobacteria
- Aerobic eukaryotes
- Plastid endosymbiosis
- Algae
- Cambrian explosion
- Land plants
Great Rusting Event
- Occurred when iron reacted with oxygen
Archaea
- Ancient bacteria found in Yellowstone
- Deep-sea mining threatens archaea biodiversity
Methane
- Produced in landfills, rice fields, and oxygen-deprived areas
- Released by methanobacterium archaea
Mass Extinctions
- Not excessive in Earth's history
Interacting Spheres
- Hydrosphere: Liquid and frozen water
- Lithosphere: Earth's mantle, crust, and core
- Atmosphere: Gases around air
- Biosphere: All living organisms
Soil
- A mix of inorganic and organic matter
Reservoirs
- Different capacities for holding things (e.g., money in a bank, nitrogen in the atmosphere)
Nitrogen
- Most limiting nutrient for food production
- 78% of the atmosphere is Nitrogen (N2)
- Nitrogen-fixing bacteria (e.g., in legume roots) break the triple bond of N2 converting it to ammonia (NH4)
- Plants can only access nitrates (NO3) and ammonia (NH4)
- Cyanobacteria are also nitrogen-fixing!
Fluxes
- Rates of exchange between reservoirs (e.g., gallons per year)
Nitrogen Cycle
- Nitrogen fixation: Atmospheric nitrogen (N2) converted to ammonium (NH4+) or nitrate (NO3-) by nitrogen-fixing bacteria, lightning, and industrial processes
- Nitrification: Ammonium (NH4+) is oxidized to nitrate (NO3-) by nitrifying bacteria
Carbon Dioxide
- Vibrates, absorbing and re-radiating longwave radiation
- Oxygen and Nitrogen do not absorb longwave radiation
- Methane has 9 different vibration modes, absorbing more longwave radiation
- Greenhouse Effect: Water vapour absorbs IR wavelength range, while Nitrogen and Oxygen have little to no absorption
Heat Transmission
- Radiation: Heat transfer through electromagnetic waves
- Conduction: Heat transfer through direct contact
- Convection: Heat transfer through the movement of fluids
Greenhouse Effect
- Certain atmospheric components contribute to the Greenhouse Effect, absorbing and re-emitting longwave radiation
Long-Term Carbon Cycle and Climate
- The amount of heating affects long-term climate
- Tectonic plate movement influences the rate of carbon release from the Earth's interior
- Uplift of the Himalayas 50 million years ago increased chemical weathering, pulling more carbon into the slow carbon cycle
- This shift resulted in the transition from a warm Cretaceous period to a glacial Pleistocene period, effectively resetting Earth's thermostat
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Description
This quiz covers key concepts from environmental science related to biogeochemical cycles, including the nitrogen and phosphorus cycles, carbon cycles, and feedback mechanisms in ecosystems. Understand how these cycles impact freshwater systems and the planet's boundaries. Explore the roles of keystone species and the significance of feedback in environmental stability.