conditions for life on earth

Question 1

how do we know the early conditions on earth?

Answer 1

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

Question 2

how does the ozone protect life?

Answer 2

-produced by chemical reactions involving oxygen and UV light in stratosphere
-filters out harmful UV radiation from sun

Question 3

where did oxygen come from?

Answer 3

-oceans
-CO2 dissolved in water & carbonates were precipitated
-oxygen produced by photosynthetic bacteria then by algae and plants

Question 4

what are some changes in the atmosphere?

Answer 4

-first billion years- intense volcanic activity, released gases that formed early atmosphere, mainly CO2
-water vapour condensed forming oceans
-volcanoes also produced nitrogen

Question 5

what is the composition of the atmosphere?

Answer 5

-78% nitrogen
-21% oxygen
-0.93% argon
-0.04% carbon dioxide

Question 6

what is the goldilocks zone?

Answer 6

life possible, maintain liquid water

Question 7

what is orbital behaviour?

Answer 7

axis=seasons
rotation=daily variations in temp

Question 8

what is the magnetosphere?

Answer 8

caused by molten iron core, deflects ‘solar winds’, prevents biologically damaging radiation reaching earths surface

Question 9

how has transpiration caused environmental change?

Answer 9

-once plants evolved & colonised the land, transpiration returned water vapour to atmosphere & increased rainfall in other areas, making growth of more plant life possible

Question 10

how has carbon sequestration caused environmental change on earth?

Answer 10

-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

Question 11

how has biogeochemical cycles caused environmental damage on earth?

Answer 11

-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.

Question 12

how has atmospheric oxygen caused environmental damage?

Answer 12

• 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

Question 13

what are some reasons for how life on earth caused environmental damage?

Answer 13

1. atmospheric composition
2. biogeochemical cycles
3. carbon sequestration
4. transpiration

Question 14

how does the magnetic field make earth suitable for life?

Answer 14

molten layers beneath crust produce earths magnetic field, deflects ‘solar winds’ & stops biologically damaging radiation reaching earths surface

Question 15

how does speed of rotation make earth suitable for life?

Answer 15

temp of earths surface rise when exposed to sunlight and falls when not

Question 16

how does axis of rotation make earth suitable for life?

Answer 16

at an angle to its orbit around the sun, producing seasons

Question 17

how does the distance from the sun make earth suitable for life?

Answer 17

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

Question 18

how does mass make earth suitable for life?

Answer 18

atmosphere included elements such as carbon,hydrogen, oxygen,nitrogen. atmospheric pressure high enough to prevent all liquid water from boiling

Question 19

what conditions make earth suitable for life?

Answer 19

1.mass
2.distance from sun
3.axis of rotation
4.speed of rotation
5.magnetic field

Question 20

what factors may increase the albedo affect?

Answer 20

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

Question 21

what is the albedo affect?

Answer 21

light surfaces reflect more heat than dark surfaces

Question 22

what does insolation mean?

Answer 22

incoming solar radiation that reaches the surafce

Question 23

why is absorbing UV radiation so important in water?

Answer 23

provides protection to organisms (especially ozone)

Question 24

why is specific heat capacity so important in water?

Answer 24

causes water to warm up and cool down slowly

Question 25

why is ice expansion in freezing water so important?

Answer 25

ice floats and insulates water underneath keeping it warm

Question 26

why is temperature control so important in water?

Answer 26

evaporation of water from skin cools the body down

Question 27

why is transport so important in water?

Answer 27

water is the solvent in blood and sap, transporting dissolved gases, sugars, amino acids

Question 28

why are enzymes so important in water?

Answer 28

control all reaction in living organisms, high temperature= enzyme denature

Question 29

why is water so important?

Answer 29

1. enzymes
2. transport
3. temperature control
4. expansion on freezing
5. high specific heat capacity
6. absorbs UV radiation

Question 30

what is the modern atmosphere mainly made up of?

Answer 30

nitrogen, oxygen, carbon dioxide

Question 31

what was the early atmosphere mainly made up of?

Answer 31

carbon dioxide, methane, nitrogen

Question 32

how does earth have an atmosphere?

Answer 32

due to gravity, which is caused by mass

Question 33

why is the position in the solar system important?

Answer 33

-goldilocks zone
-temperatures are stable
-liquid water

Question 34

how does the magnetosphere protect life?

Answer 34

-deflects harmful solar material coming from the sun

Question 35

explain how the earths tilt leads to seasonal variations

Answer 35

-when the earths axis points towards the sun, it is summer for that hemisphere
-when the earths axis points away, it is winter