1. Conditions for Life on Earth

Question 1

features of earth that created suitable conditions for life

Answer 1

mass
distance from the sun
axis or rotation
speed of rotation
magnetic field

Question 2

mass

Answer 2

mass of earth was great enough to stop gases escaping into space. gases like carbon, hydrogen, oxygen, and nitrogen.

Question 3

distance from the sun

Answer 3

the light emitted from the sun and the distance from the sun were suitable to produce temperatures on earth that would be suitable for life. being too close or too far from the sun prevented liquid water

Question 4

axis of rotation

Answer 4

at an angle to its orbit around the sun which produced seasonal variations in conditions as the earth orbits the sun

Question 5

speed of rotation

Answer 5

the temperature of the earths surface rises when it is exposed to sunlight and falls when it is not. 24 hour rotation prevents temperature extremes

Question 6

magnetic field

Answer 6

molten layers beneath the crust produce the earths magnetic field that deflects the ‘solar wind’ and prevents biologically damaging radiation reaching the earths surface.

Question 7

early conditions on earth that allowed life to develop

Answer 7

presence of liquid water
temperature range
atmospheric gases
solar insolation

Question 8

factors affecting presence of liquid water

Answer 8

solvent water
transport within organisms
temperature control
anomalous expansion on freezing
high specific heat capacity
aquatic habitats
absorbtion of UV radiation

Question 9

temperature range

Answer 9

most areas of earth have temperatures between 0°C to 35°C, so most areas are warm enough to have liquid water but not hot enough to denature proteins

Question 10

atmospheric gases

Answer 10

carbon dioxide for photosynthesis and the synthesis of carbohydrates, proteins, and lipids

nitrogen for protein synthesis

Question 11

solar insolation

Answer 11

sunlight provides the energy for photosynthesis. The heat produced by the absorption of sunlight provides the energy that drives the water cycle and warms the earths surface and the oceans.

Question 12

how life on earth caused environmental change

Answer 12

atmospheric oxygen
carbon sequestration
biogeochemical cycles
transpiration

Question 13

atmospheric oxygen

Answer 13

once all the iron had reacted with oxygen, the surplus dissolved oxygen built up in the oceans. Much of this was released into the atmosphere where concentrations started to rise about 2.45 billion years ago

Question 14

more atmospheric oxygen

Answer 14

oxygen in the atmosphere absorbed UV light, producing a dynamic equilibrium of reactions involving O3, O2, and O. Absorption of UV light made life on earths surface possible. The time period we yeh oxygen was building up lasted until about 540m years ago

Question 15

carbon sequestration

Answer 15

carbon dioxide is a greenhouse gas and helps to retain heat energy in the atmosphere. photosynthetic organisms, photoautotrophs, absorbed carbon dioxide, some of which was stored in geological sediments such as carbonate rocks and fossil fuels

Question 16

biogeochemical cycles

Answer 16

as a greater variety of organisms evolved, inter-connected biological processes developed which produced biogeochemical cycles. these meant that relatively small amounts of some nutrient elements could support life over long periods of time without the resources becoming depleted.

Question 17

transpiration

Answer 17

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