Conditions for Life on Earth Flashcards
What are the 5 conditions that allowed life to develop on Earth?
- Distance from the Sun
- Insolation
- Orbital behaviour
- Magnetosphere
- Atmosphere
How did distance from the Sun allow life to develop on Earth?
Provides a suitable temperature range on Earth which maintains liquid water and allows for photosynthesis
How did insolation allow life to develop on Earth?
Provides a suitable temperature range on Earth due to its atmospheric behaviour
How did orbital behaviour allow life to develop on Earth?
Earth’s orbit and its rotation and tilt on its axis controls daily and seasonal variations in insolation and therefore temperature
How did the magnetosphere allow life to develop on Earth?
Deflects harmful solar radiation which could be biologically damaging
How did the atmosphere allow life to develop on Earth?
Earth’s mass and gravitational force retains an atmosphere which provides gaseous resources and maintains liquid water (due to pressure and temperature)
In which 4 ways did early life on Earth cause environmental change?
Biogeochemical cycles
Oxygen production
Ozone layer
Carbon sequestration
How did biogeochemical cycles cause environmental change?
Linked cycles prevent the build-up of waste products and the shortage of resources
How did oxygen production cause environmental change?
Early photosynthesisers such as cyanobacteria produced oxygen which allowed for organisms to develop using aerobic respiration
How did the ozone layer cause environmental change?
Reactions between oxygen and UV in the stratosphere created the ozone layer which protects Earth from harmful UVC and UVB radiation
How did carbon sequestration cause environmental change?
Photosynthetic organisms reduced atmospheric CO2 levels which reduced the greenhouse effect
What are the 5 examples of proxy data to determine past conditions on Earth?
- Historical data
- Coral reef analysis
- Pollen analysis
- Dendrochronology
- Ocean and lake sediment analysis
How does historical data help determine past conditions on Earth?
Sources such as ships logs, diaries and news articles provide information about the weather and climate at the time
How does coral analysis help determine past conditions on Earth?
The density of a coral reef changes due to temperature and the presence of carbon for the CaCO3 structure
How does pollen analysis help determine past conditions on Earth?
Pollen grains can be used to determine which types of plants were present in the past
How does dendrochronology help determine past conditions on Earth?
Thick tree rings indicate warmer, wetter years whereas thin tree rings indicate colder, drier years
How does ocean and lake sediment analysis help determine past conditions on Earth?
Pollen and other fossilised organisms can be found in sediments which may only be present in certain climates
What are the limitations of proxy methods?
- Historical data may be subjective
- Trees do not grow in all climates
- Coral is only present in specific climates
- Many areas lack data collection
What are the 3 examples of improved methods to determine conditions on Earth?
- Ice-core analysis
- Satellite imagery
- Weather balloons
How can ice-cores help determine past conditions on Earth?
Thick layers of ice indicate warmer, wetter years whereas thin layers of ice indicate colder, drier years
How can ice-core isotope analysis help determine past conditions on Earth?
The ratio of O-16 to O-18 can be measured using advanced scientific equipment to determine past climates, as O-18 is a heavier isotope and will evaporate at a higher rate during warmer years
What are the advantages of improved methods?
- Collection of long-term data sets
- Electronic monitoring systems
- Improved carriers (e.g. weather balloons)
