The Conditions For Life On Earth

Question 1

How long ago did earth form?

Answer 1

4.6 billion years ago

Question 2

Why was mass important for for life?

Answer 2

Prevented most gases from escaping into space

Atmospheric pressure was high enough to prevent all liquid water from boiling

Question 3

What are the essential elements for life?

Answer 3

Carbon
Hydrogen
Oxygen and nitrogen

Question 4

How were the essential elements found on early earth?

Answer 4

Methan
Ammonia
Carbon dioxide

Question 5

Why is water vital?

Answer 5

General physiological solvent in most biological reactions
Transport
Temperature regualtion
For aquatic/ early life

Question 6

Why is distance from the sun important?

Answer 6

Produces temperatures suitable for life
Too close or far would mean there would be no liquid water
The time taken to produce night and day cycles was fast enough to reduce extreme temperatures

Question 7

Why is the axis of rotation important?

Answer 7

The angle at which earth orbits the sun produces easonal variations

Question 8

Why is speed of rotation important?

Answer 8

24hr period of rotation reduces temperature extremes

Question 9

Why is magnetic field important?

Answer 9

Deflects solar winds and prevents biologically damaging radiation reaching earths surface

Question 10

Why is solvent water important

Answer 10

General physiological solvent

Most chemical reactions in living organisms involve reactants dissolved in water.

Question 11

Why is water important for transport in organisms

Answer 11

Water is the solvent in the blood and sap where it transports dissolved gases, sugars, amino acids, mineral nutrienst and waste products.

Question 12

Why is water important for temperature control?

Answer 12

Evapouration of water abosorbs heat causing temperatures to decline

Question 13

Why is it important that water anomalously expands on freezing

Answer 13

Water is most dense at 4*c so water that is cooler than this floats, stopping the convection currents that may have cooled the whole water body

Question 14

Why is it imporant that water has a high heat capacity

Answer 14

Water warms and cools down slowly which helps to moderate the rate and size of temperature change

Question 15

What aquatic habitats does water provide?

Answer 15

Rivers
Oceans 
Seas 
Marshes 
Lakes
Ponds

Question 16

Why is it important that water absorbs UV

Answer 16

Protected living organisms in the oceans before the ozone layer developed which absorbed UV in the stratosphere

Question 17

Why was temperature range important?

Answer 17

Most areas of earth have temperatures between 0-35*c so most areas are warm enough to have liquid water but not hot enough to denature proteins

Question 18

Why is carbon dioxide important?

Answer 18

Photosynthesis

Synthesis of carbohydrates, proteins and lipids

Question 19

Why is nitrogen important

Answer 19

Protein synthesis

Question 20

Why is solar insolation important

Answer 20

Sunlight provides the energy for photosynthesis
Heat produced by sunlight drives the water cycle and warms the surface and oceans
Amount abosrbs depends on albedo
Composition of the atmosphere controls how much infrared is aborobed and converted to heat

Question 21

What is the albedo of a surface?

Answer 21

It’s reflective power or lack there of

Question 22

What are Archaea?

Answer 22

Photosynthetic algae

Question 23

When did Archaea form?

Answer 23

2.7 billion years ago

Question 24

Why are Archaea important?

Answer 24

Had the ability to photosynthesise and produce oxygen as waste.

Question 25

How did oxygen get into the atmosphere?

Answer 25

Oxygen reacted with iron in the oceans until all reaactions had taken the place then a surplus of O2 was released into the atmopshere 2.45 billion years ago

Question 26

Why was it important for oxygen to be in the atmopshere?

Answer 26

Aborobed UV light producing a dynamic equillibirum of reactions with O3, O2 and O
Important as made life on the surface possible

Question 27

What was the period of oxygen period bulid up called?

Answer 27

Proterzoic ended 540million years ago

Question 28

Why is carbon sequestration important?

Answer 28

Photosynthetic organims, photoautotrophs absorbed CO2 some of which is stored in geological sediments and fossil fuels
This help reduce long term temperature rise

Question 29

How much brighter does the sun get every 1 billion years?

Answer 29

10%

Question 30

Why are biogeochemical cycles important?

Answer 30

Meant relatively small amounts of some nutrient elemnts could support life over long periods of time without resources being depleted

Question 31

Why was tranpiration important?

Answer 31

Transpiration returned water vapour to the atmosphere and increased rainfall in other areas making more plant growth possible

Question 32

What can a radioisotope composition be used for

Answer 32

Used to date samples such as the ratio of carbo-12 to carbon-14
Oxygen-18 to oxygen-16 used to estimate past temperatures
Compostion of past atmopshere analysed from bubbes in ice cores