Chapter 1 - Conditions For Life On Earth Flashcards
(31 cards)
In what ways is water essential for all living organisms? (5 ways)
Transport Temperature control Physiological solvent Expansion on freezing High specific heat capacity
State the early conditions on earth that allowed life to evolve
Large amounts of water
Appropriate temperature range
Suitable ambient gases
Light and radiation from the sun
Explain why water is important for transport in living organisms
Water is a solvent in the blood and sap. It transports oxygen, carbon dioxide, sugars, amino acids, waste products and mineral nutrients etc.
Why is water important for temperature control?
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
What is meant by the term ‘physiological function’?
Any substance that is involved in chemical reactions in a living organism has a physiological function
What is ‘specific heat capacity’?
The measure of the amount of energy that is needed to heat up a particular mass of material through a particular temperature rise.
Why can water be described as having a ‘high specific heat capacity’?
Water warms up and cools down slowly, helping to moderate the rate and size of temperature changes
Why is it useful for water to expand on freezing?
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
Why is an appropriate temperature range important for life on Earth?
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
What is thermopile can bacteria and where is it typically found?
Bacteria that can withstand much higher temperatures, sometimes over 80C. Thermophilic bacteria is found around hot volcanic vents and springs
Within what temperature range are most bacterias found?
0-40C
Give an example of an ambient gas found on earth
Oxygen
Carbon dioxide
Nitrogen
Define ‘ambient gases’
The surrounding environmental gases that are available to organisms
Define ‘atmosphere’
The gases that surround the earth
What is the importance of sunlight for living organisms?
Provides the energy for photosynthesis
Why is UV radiation harmful to earth?
It can be absorbed by cells and cause cells to become mutated and cancerous
What about the position of the earth in the solar system important and what can be affected by it?
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
What is transpiration?
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
How has atmospheric oxygen brought about environmental change on earth?
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.
What does the presence of oxygen in the environment rely on?
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
Define ‘photolysis’
The splitting of molecules by light, including the splitting of water molecules in the early atmosphere, producing oxygen
What reaction takes place in order to produce ozone?
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.
What role does ozone play?
Provides protection against radiation from the sun, such as UV by absorbing it
What chemical makes up ozone?
O3
