Conditions for Life on Earth

Question 1

What are the 5 conditions that allowed life to develop on Earth?

Answer 1

• Distance from the Sun
• Insolation
• Orbital behaviour
• Magnetosphere
• Atmosphere

Question 2

How did distance from the Sun allow life to develop on Earth?

Answer 2

Provides a suitable temperature range on Earth which maintains liquid water and allows for photosynthesis

Question 3

How did insolation allow life to develop on Earth?

Answer 3

Provides a suitable temperature range on Earth due to its atmospheric behaviour

Question 4

How did orbital behaviour allow life to develop on Earth?

Answer 4

Earth’s orbit and its rotation and tilt on its axis controls daily and seasonal variations in insolation and therefore temperature

Question 5

How did the magnetosphere allow life to develop on Earth?

Answer 5

Deflects harmful solar radiation which could be biologically damaging

Question 6

How did the atmosphere allow life to develop on Earth?

Answer 6

Earth’s mass and gravitational force retains an atmosphere which provides gaseous resources and maintains liquid water (due to pressure and temperature)

Question 7

In which 4 ways did early life on Earth cause environmental change?

Answer 7

Biogeochemical cycles
Oxygen production
Ozone layer
Carbon sequestration

Question 8

How did biogeochemical cycles cause environmental change?

Answer 8

Linked cycles prevent the build-up of waste products and the shortage of resources

Question 9

How did oxygen production cause environmental change?

Answer 9

Early photosynthesisers such as cyanobacteria produced oxygen which allowed for organisms to develop using aerobic respiration

Question 10

How did the ozone layer cause environmental change?

Answer 10

Reactions between oxygen and UV in the stratosphere created the ozone layer which protects Earth from harmful UVC and UVB radiation

Question 11

How did carbon sequestration cause environmental change?

Answer 11

Photosynthetic organisms reduced atmospheric CO2 levels which reduced the greenhouse effect

Question 12

What are the 5 examples of proxy data to determine past conditions on Earth?

Answer 12

• Historical data
• Coral reef analysis
• Pollen analysis
• Dendrochronology
• Ocean and lake sediment analysis

Question 13

How does historical data help determine past conditions on Earth?

Answer 13

Sources such as ships logs, diaries and news articles provide information about the weather and climate at the time

Question 14

How does coral analysis help determine past conditions on Earth?

Answer 14

The density of a coral reef changes due to temperature and the presence of carbon for the CaCO3 structure

Question 15

How does pollen analysis help determine past conditions on Earth?

Answer 15

Pollen grains can be used to determine which types of plants were present in the past

Question 16

How does dendrochronology help determine past conditions on Earth?

Answer 16

Thick tree rings indicate warmer, wetter years whereas thin tree rings indicate colder, drier years

Question 17

How does ocean and lake sediment analysis help determine past conditions on Earth?

Answer 17

Pollen and other fossilised organisms can be found in sediments which may only be present in certain climates

Question 18

What are the limitations of proxy methods?

Answer 18

• Historical data may be subjective
• Trees do not grow in all climates
• Coral is only present in specific climates
• Many areas lack data collection

Question 19

What are the 3 examples of improved methods to determine conditions on Earth?

Answer 19

• Ice-core analysis
• Satellite imagery
• Weather balloons

Question 20

How can ice-cores help determine past conditions on Earth?

Answer 20

Thick layers of ice indicate warmer, wetter years whereas thin layers of ice indicate colder, drier years

Question 21

How can ice-core isotope analysis help determine past conditions on Earth?

Answer 21

The ratio of O-16 to O-18 can be measured using advanced scientific equipment to determine past climates, as O-18 is a heavier isotope and will evaporate at a higher rate during warmer years

Question 22

What are the advantages of improved methods?

Answer 22

• Collection of long-term data sets
• Electronic monitoring systems
• Improved carriers (e.g. weather balloons)