Stage 2 Biology – Ecosystems Notes
E11.
The level of human population is a biological and ethical issue
·
Current population over 6 million (7 million in
2011)
o
Placing a huge strain on available resources
o
In developed countries, high standard of living,
but the amount of energy consumed is 20-30 times more than by a person in a
developing country
·
Fossil fuels
o
Most of our energy comes from burning fossil
fuels (coal, gas, oil)
o
Finite – more and more expensive to locate and extract
deposits
o
Alternative sources of energy – sun, wind,
nuclear
§
Disposal of waste
§
Sun and wind need advances in technology
·
Soil/land availability
o
Challenge to provide sufficient food for each
individual
o
Nearly all land that can be cultivated is
already used
o
Removal of native vegetation leads to erosion,
nutrient depletion and high salinity
o
Needs to be a continuation of ecologically
sustainable farming practices and improved crops
§
New wheat and rice resulted in increased yields
§
But now need to use genetic engineering to
develop varieties that are more nutritious and give higher yields with less
input and resistance to pests and diseases and ability to grow in poor soils
·
Water
o
Many areas where fresh water is not available
readily
o
3.4 billion people use around 50 litres per day,
but average Australians use 250-300 litres
o
In India, three children die every minute from
diseases from polluted water; 1/3 of deaths in developing countries
·
Biodiversity
o
20% of world’s biodiversity will be lost in the
next 30 years
o
Organisms are important for food, medicine,
drugs, clothing, maintaining cycling of matter/energy
·
Exponential growth of the human population
o
For 99% of human history, there was no growth,
but the numbers have increased exponentially in the last 1%
o
China and India have almost 40% of the world’s
population
o
Usually populations stabilise at the carrying
capacity
o
Exponential growth occurs as
§
Number of breeding individuals increases
§
Plenty of available resources
(food/water/shelter)
§
Competition increases and resources diminish
§
Predators, disease and waste accumulation keep
numbers in check
o
Humans have extended the carrying capacity with increasing
technology, development of medicine and agriculture
o
Growth of human population is placing huge
demands on resources such as food, water and energy
o
Contraceptives reduce rate of population growth;
environmentalists are being heard more
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