Gaia hyp

Question 1

earliest evidence of life

Answer 1

• ALH8400,1 meteorite fell to earth 20myr in the Arctic

- the structures inside the meteorite were biogenic, fossilised cells

Question 2

what does the Gaia hyp explain?

Answer 2

all organisms and their inorganic surroundings on earth are closely related to form a single and self-regulating complex system, maintaining the conditions for life

Question 3

what did Lovelock do to be able to say that life is involved in ocean salinity regulation?

Answer 3

constructed evaporation lagoons

Question 4

how do oceans get rid of salt?

Answer 4

• chemical exchange with newly forming ocean crust at mid-ocean ridges and removal of water in hydrous form and sediments at subduction zones can remove elements from water

Question 5

what is the goldilocks zone?

Answer 5

solar systems that have planets with water

Question 6

what is the habitable zone?

Answer 6

a narrow zone in which liquid water can exist on the surface

Question 7

what is the faint young sun puzzle?

Answer 7

• suggests atmospheric greenhouse must have been greater in the past because:
• science suggests the sun was 30% less bright 4.5 gyr ago

Question 8

what is the Urey/ Ebelman reaction

Answer 8

silicate weathering

Question 9

equation for silicate weathering

Answer 9

silicate weathering
CaSiO3+2CO2+H2O -> Ca2+ +2HCO3- +SiO2
carbonate deposition 
Ca2+ +2HCO3- -> CaCO3+CO2+H2O
net result
CaSiO3+CO2 -> CaCO3 + SiO2

Question 10

what broadens the habitable zone?

Answer 10

silicate weathering -ve feedback