Chapter 1 - Conditions For Life On Earth

Question 0

In what ways is water essential for all living organisms? (5 ways)

Answer 0

Transport 
Temperature control 
Physiological solvent 
Expansion on freezing 
High specific heat capacity

Question 1

State the early conditions on earth that allowed life to evolve

Answer 1

Large amounts of water
Appropriate temperature range
Suitable ambient gases
Light and radiation from the sun

Question 2

Explain why water is important for transport in living organisms

Answer 2

Water is a solvent in the blood and sap. It transports oxygen, carbon dioxide, sugars, amino acids, waste products and mineral nutrients etc.

Question 3

Why is water important for temperature control?

Answer 3

The evaporation of water from the skin can be used to control the body when it is too hot. Heat can also be transported in the blood, for instance from the core of the body to the skin to increase heat loss

Question 4

What is meant by the term ‘physiological function’?

Answer 4

Any substance that is involved in chemical reactions in a living organism has a physiological function

Question 5

What is ‘specific heat capacity’?

Answer 5

The measure of the amount of energy that is needed to heat up a particular mass of material through a particular temperature rise.

Question 6

Why can water be described as having a ‘high specific heat capacity’?

Answer 6

Water warms up and cools down slowly, helping to moderate the rate and size of temperature changes

Question 7

Why is it useful for water to expand on freezing?

Answer 7

As ice floats it can keep very cold air above the ice separate from the water below, which prevents the water from cooling as much as it would have without the ice. This prevents lakes in cold areas from freezing solid in winter

Question 8

Why is an appropriate temperature range important for life on Earth?

Answer 8

Temperature ranges on earth allow water to exist in three different states. Most areas on earth are above 0C which allows water to be present as a liquid. Most enzymes require liquid water as a solvent and denature at higher temperatures

Question 9

What is thermopile can bacteria and where is it typically found?

Answer 9

Bacteria that can withstand much higher temperatures, sometimes over 80C. Thermophilic bacteria is found around hot volcanic vents and springs

Question 10

Within what temperature range are most bacterias found?

Answer 10

0-40C

Question 11

Give an example of an ambient gas found on earth

Answer 11

Oxygen
Carbon dioxide
Nitrogen

Question 12

Define ‘ambient gases’

Answer 12

The surrounding environmental gases that are available to organisms

Question 13

Define ‘atmosphere’

Answer 13

The gases that surround the earth

Question 14

What is the importance of sunlight for living organisms?

Answer 14

Provides the energy for photosynthesis

Question 15

Why is UV radiation harmful to earth?

Answer 15

It can be absorbed by cells and cause cells to become mutated and cancerous

Question 16

What about the position of the earth in the solar system important and what can be affected by it?

Answer 16

Distance from the sun - controls light levels and temperatures
Daily rotation - controls the duration of day and night therefore the range of temperatures
Tilted axis - controls seasonal variations on earth
Molten layers beneath the crust - produce the Earth’s magnetic field, which deflects harmful radiation coming from the sun

Question 17

What is transpiration?

Answer 17

The loss of water by evaporation from the stomata of the leaves. Water is absorbed through the roots and travels up through the xylem in the shoots. From there, it evaporates as water vapour through the stomata

Question 18

How has atmospheric oxygen brought about environmental change on earth?

Answer 18

Oxygen is a reactive element. The concentration of oxygen declined as it combined with other elements such as the oxidation weathering with elements such as iron on the surface of exposed rocks.

Question 19

What does the presence of oxygen in the environment rely on?

Answer 19

Processes that continually replace it as others remove it. Oxygen is released by photolysis of water and photosynthesis of photosynthetic plants which release much larger amounts of oxygen

Question 20

Define ‘photolysis’

Answer 20

The splitting of molecules by light, including the splitting of water molecules in the early atmosphere, producing oxygen

Question 21

What reaction takes place in order to produce ozone?

Answer 21

Oxygen absorbs UV radiation from the sun which causes the oxygen molecules to split. This produces monatomic oxygen (consisting of one atom) that reacts with diatomic oxygen to produce ozone. Ozone develops as the reaction continues.

Question 22

What role does ozone play?

Answer 22

Provides protection against radiation from the sun, such as UV by absorbing it

Question 23

What chemical makes up ozone?

Answer 23

O3

Question 24

How has atmospheric carbon dioxide brought about environmental change on earth?

Answer 24

Carbon dioxide is an essential greenhouse gas and helps to retain heat in the atmosphere. Without it, earth would be too cold for life to exists. However, excessive carbon dioxide can cause temperatures to rise too much.

Question 25

How is carbon dioxide released into the atmosphere naturally?

Answer 25

Volcanoes

Question 26

How have living organisms helped to regulate carbon dioxide levels?

Answer 26

Removing carbon dioxide through processes such as photosynthesis. The carbon is stored in fossil fuels and carbonate rocks such a limestone and chalk

Question 27

Explain how the water cycle has brought about environmental change on earth

Answer 27

Heat energy from the sun causes water from the sea to evaporate. This may be carried over land where it falls as rain and flows back into the sea. Most rain falls relatively close to the coast by transportation by plants returns water vapour to the atmosphere so it can be blown further inland.

Question 28

Why is transpiration important for plants?

Answer 28

It is important in the cooling of plants and in the upward transport of dissolved minerals

Question 29

That are the three spheres that make up the biosphere

Answer 29

Atmosphere
Hydrosphere
Lithosphere

Question 30

What is the term given to ‘all living things on earth’?

Answer 30

Biosphere