Paper 2 : Conditions For Life On Earth

Question 1

Formation of earth

Answer 1

Earth formed 4.6Ga

• gravity pulled rock fragments together
• ball of molten rock created due to thermal energy
• surface cooled to form crust

Physical features made earth suitable for development of life

Question 2

Earth’s mass - elements

Answer 2

Mass of earth + force of gravity retain the Earth’s atmosphere

Prevents essential elements from escaping:
-carbon - organic compounds
-oxygen - aerobic respiration
-hydrogen - water
-nitrogen - protein synthesis (AA)

In the early atmosphere these elements were present in ammonia, methane, CO² and water vapour
-important for natural greenhouse
effect and climate control

Question 3

Earth’s mass - water

Answer 3

Mass of earth + force of gravity influence atmospheric pressure
-high enough to prevent liquid
water from boiling