Conditions for life on earth

Question 1

How is an atmosphere retained on earth?

Answer 1

By the mass of the earth and gravity

Question 2

How is liquid water maintained on earth and why is this important?

Answer 2

Atmospheric pressure stops water from boiling.
Water is important as it is the physiological solvent in which most biological reactions take place.

Question 3

What does the atmosphere provide?

Answer 3

Gaseous resources, CO2, CH4, NH2

Question 4

What does the distance from the sun allow on earth

Answer 4

A suitable amount of insolation which produced suitable temps for earth.

Question 5

What is incoming insolation controlled by?

Answer 5

Surface albedo, infrared absorption and the atmosphere

Question 6

What is the axis of rotation of earth and what does it produce?

Answer 6

The axis of rotation is at an angle to its orbit around the sun, it produces seasonal variations.

Question 7

What does the speed of rotation of earth allow?

Answer 7

The 24hr period of rotation stops temperature extremes

Question 8

How is the magnetic field/magnetosphere produced and what does it do?

Answer 8

Produced by the earths molten core.
The magnetic field deflects solar wind and prevents damaging radiation from reaching the earth.

Question 9

When did life first develop on earth?

Answer 9

3.5 billion years ago

Question 10

How did liquid water allow life to develop?

Answer 10

As a solvent for chemical reactions.
Transport of dissolved gases, nutrients etc in blood and sap.
Temperature control, High SHC
Aquatic habitats
Absorbed UV radiation before the ozone developed which protected aquatic organisms

Question 11

How was oxygen first produced?

Answer 11

Photosynthetic bacteria in the oceans developed the ability to photosynthesise and release oxygen.

Question 12

How did oxygen get into the atmosphere?

Answer 12

All the oxygen being produced by photosynthetic bacteria reacted with iron in the oceans.
Once all the iron had reacted, surplus oxygen built up and diffused into the atmosphere

Question 13

What did oxygen in the atmosphere do?

Answer 13

Oxygen absorbed UV light in the stratosphere producing O, O2 and O3.
O3 is ozone and so the build up of this allowed life to develop on earth as less UV radiation was reaching earth.

Question 14

What happened after the ozone developed?

Answer 14

Anaerobic organisms died out or they developed a way to aerobically respire and lived on land. Includes photoautotrophs and animals

Question 15

What did the photoautotrophs do once developed on land?

Answer 15

They absorbed CO2, this reduced the levels of CO2 in the atmosphere and therefore a temperature rise

Question 16

What is CO2?

Answer 16

Carbon dioxide, it is a GH gas so it helps retain heat in the atmosphere

Question 17

What did the colonisation of plants allow?

Answer 17

Transpiration where water vapour was returned to the atmosphere and increased rainfall allowing more plants to grow.

Question 18

What did a greater variety of organisms evolving allow?

Answer 18

Allowed inter-connected systems and biogeochemical processes to develop.

Question 19

What do biogeochemical cycles do?

Answer 19

They prevent the build up of wastes and stop shortages of resources.

Question 20

What are the limitations of early methods of measuring climate?

Answer 20

Lack of historical data
Proxy data not being reliable as it can be subjective
Lack of scientific equipment
Lack of data collection in certain areas
Proxy data- pollen grains, dendrochronology,

Question 21

What are some improved methods to measure climate change?

Answer 21

Using scientific equipment/electronic monitoring equipment
Gas analysis of ice cores
Satellites
Remote monitoring equipment for areas not accessible

Question 22

How can ice cores be analysed for past climate conditions?

Answer 22

Analysing the air bubbles in ice cores to detect the isotopes of oxygen and composition of atmosphere.
More O18 compared to O16 indicates the temperature was lower.
Analyse for methane, CO2.
If the ice layers are thick it indicates a colder temperature as more snow fall.

Question 23

What satellites take data on the environment?

Answer 23

CLOUDSAT- measures clouds to measure precipitation, uses a radar and takes photos.
CALIPSO- Uses laser light from a lidar, it takes global measurements of atmospheric particles to monitor the climate

Question 24

How do we know if there is significant change in climate?

Answer 24

Rapid or unusual change

Question 25

How are pollen grains monitored for data?

Answer 25

Particular species of preserved pollen grains in lakes can indicate the climate by using radio-carbon dating on the organic matter