How the Earth Works: Biosphere Flashcards
Define biogeochemistry.
The study of the chemical, physical, geological and biological processes and reactions that govern the composition of the natural environment.
Give examples of sources of carbon.
- Volcanism & metamorphism
* Respiration (short term)
Give examples of carbon sinks.
- Photosynthesis (short term)
- Air-sea gas exchange (short term)
- Weathering
- Carbonate precipitation
- Organic burial
- Subduction
What is the largest C sink in short time scales?
Photosynthesis.🌱
How is air-sea gas exchange regulated?💨🌊
Concentration gradient of CO2 between the atmosphere and ocean.
Define soil.
Multi-component, multiphase open biogeochemical systems containing living things, solids, water and air.
Define active layer.
Overlaying soil that experiences seasonal freeze-thaw.
Define permafrost.❄️
Subsurface earth materials below 0 to 2C for >2 years.
Define ecosystem.
A community of organisms and their physical environment interacting together as an ecological unit.
What is the Oparin-Haldane hypothesis?
Life arose from chemical reactions that were initiated in a strongly reducing early atmosphere and came to completion in oceans.
What was the Miller-Urey experiment?
- Tested the O-P hypothesis
- Mixture of gases analogous to Earth’s early atmosphere placed in flask
- Powerful electric discharges were set off (lightening)
- Organic compounds produced including amino acids.
What is the RNA World theory?
Unlike O-H hypothesis and Miller-Urey experiment which put emphasis on proteins and amino acids as the precursors for life but this suggests it is RNA.
Where did life begin?
- O-H hypothesis and RNA World suggest surface oceans
* However may be hydrothermal vents.
What evidence is there for life beginning in hydrothermal vents?
More protected from UV, cosmic bombardment and environmental fluctuations
Describe the rise of oxygen.
•Evolution of oxygenic photosynthesis resulted in the formation of the stratospheric ozone layer and intimately lead to the evolution of animals towards the end of the Proterozoic.
