conditions for life on earth Flashcards
how do we know the early conditions on earth?
data gaps
-lack ancient historical data
-limited coordination between researchers
-lack data collection in many areas
proxy data
-limited reliability
-reliance on proxy data
equipment issues
-lack sophisticated equipment
-inability to measure many factors
how does the ozone protect life?
-produced by chemical reactions involving oxygen and UV light in stratosphere
-filters out harmful UV radiation from sun
where did oxygen come from?
-oceans
-CO2 dissolved in water & carbonates were precipitated
-oxygen produced by photosynthetic bacteria then by algae and plants
what are some changes in the atmosphere?
-first billion years- intense volcanic activity, released gases that formed early atmosphere, mainly CO2
-water vapour condensed forming oceans
-volcanoes also produced nitrogen
what is the composition of the atmosphere?
-78% nitrogen
-21% oxygen
-0.93% argon
-0.04% carbon dioxide
what is the goldilocks zone?
life possible, maintain liquid water
what is orbital behaviour?
axis=seasons
rotation=daily variations in temp
what is the magnetosphere?
caused by molten iron core, deflects ‘solar winds’, prevents biologically damaging radiation reaching earths surface
how has transpiration caused environmental change?
-once plants evolved & colonised the land, transpiration returned water vapour to atmosphere & increased rainfall in other areas, making growth of more plant life possible
how has carbon sequestration caused environmental change on earth?
-CO2 helps retain heat energy in atmosphere
-photosynthetic organisms, photoautotrophs,absorbed CO2,some stored in carbonate rocks & fossil fuels
-reduction in atmospheric carbon dioxide levels, prevents long term temp rise
how has biogeochemical cycles caused environmental damage on earth?
-greater variety of organisms evolved, inter-connected biological processes developed, producing biogeochemical cycles
-meaning small amounts of some nutrient elements could support life over long periods of time.
how has atmospheric oxygen caused environmental damage?
- iron reacted with oxygen in oceans, surplus then dissolved oxygen built up in oceans
-oxygen in atmosphere absorbed UV light, producing dynamic equilibrium of reactions involving O3,O2,O
-time where oxygen was building lasted until 450m years ago
what are some reasons for how life on earth caused environmental damage?
- atmospheric composition
- biogeochemical cycles
- carbon sequestration
- transpiration
how does the magnetic field make earth suitable for life?
molten layers beneath crust produce earths magnetic field, deflects ‘solar winds’ & stops biologically damaging radiation reaching earths surface
how does speed of rotation make earth suitable for life?
temp of earths surface rise when exposed to sunlight and falls when not
how does axis of rotation make earth suitable for life?
at an angle to its orbit around the sun, producing seasons
how does the distance from the sun make earth suitable for life?
light emitted from sun and distance were suitable to produce temp on earth for life. time taken for earth to rotate on axis produced day/night cycles, minimising excessive heating or cooling
how does mass make earth suitable for life?
atmosphere included elements such as carbon,hydrogen, oxygen,nitrogen. atmospheric pressure high enough to prevent all liquid water from boiling
what conditions make earth suitable for life?
1.mass
2.distance from sun
3.axis of rotation
4.speed of rotation
5.magnetic field
what factors may increase the albedo affect?
1.positive feedback-earths temp drops, ice sheets grow, causing more heat to reflect and ice sheets expand further. more ice=less radiation
2.smaller distance from the equator, therefore warmer
what is the albedo affect?
light surfaces reflect more heat than dark surfaces
what does insolation mean?
incoming solar radiation that reaches the surafce
why is absorbing UV radiation so important in water?
provides protection to organisms (especially ozone)
why is specific heat capacity so important in water?
causes water to warm up and cool down slowly
why is ice expansion in freezing water so important?
ice floats and insulates water underneath keeping it warm
why is temperature control so important in water?
evaporation of water from skin cools the body down
why is transport so important in water?
water is the solvent in blood and sap, transporting dissolved gases, sugars, amino acids
why are enzymes so important in water?
control all reaction in living organisms, high temperature= enzyme denature
why is water so important?
- enzymes
- transport
- temperature control
- expansion on freezing
- high specific heat capacity
- absorbs UV radiation
what is the modern atmosphere mainly made up of?
nitrogen, oxygen, carbon dioxide
what was the early atmosphere mainly made up of?
carbon dioxide, methane, nitrogen
how does earth have an atmosphere?
due to gravity, which is caused by mass
why is the position in the solar system important?
-goldilocks zone
-temperatures are stable
-liquid water
how does the magnetosphere protect life?
-deflects harmful solar material coming from the sun
explain how the earths tilt leads to seasonal variations
-when the earths axis points towards the sun, it is summer for that hemisphere
-when the earths axis points away, it is winter
