chapter 10 biology Flashcards
what is societal collapse
societal collapse’ is the fall or disintegration of human societies, and has occurred regularly in human history. Two reasons why a society may collapse are environmental problems and failure to adapt to environmental issues.
explanation of the 2 reasons of societal collapse
Environmental problems that have traditionally led to societal collapse include: deforestation and habitat destruction; soil problems (erosion, salinization (the process by which water-soluble salts accumulate in the soil) and loss of soil fertility); water management problems; overhunting (on land and in water); and the effects of introduced species on native species.
why did Easter lslands collapse
Diamond believes that deforestation of the island destroyed the resource base the people depended on, The total deforestation may be related to the statues. trees were used to move the moai, and removal
of the trees led to soil erosion, landslides, crop failures and famine.
factors that may contribute to the weakenrng and collapse of present and future societies:
climate change caused by human activities; build-up of pollutants in the environmen| energy shortages; full human use of the Earth’s photosynthetic capacity.
explain Neolithic revolution
began in the ‘fertile crescent’ in the lViddle East about 10000 years ago, and changed forever the way that humanity interacts with the environment. The development of settled agriculture represents one of the most significant changes in human history, and enabled human populations to start growing.
factors have contributed to an increase in human population:
better healthcare
more nutritious food
cleaner water
better sanitation.
explain the population dynamic in LEDCS and MEDCS
The biggest increase in population is in economically developing countries (LEDCs) rather than in more economically developed countries (lVEDC9. High infant-death rates increase the pressure on women to have more children, and in some agricultural societies parents have larger families to provide labour for the farm and as security for the parents in old age. Lack of access to contraception, through education or medical services, also leads to increased birth rates.However, resource use in many LEDCs is much less than the resource consumption in MEDCs where population growth rates are much lower.
The human effects on the environment can be summarized by the mnemonic A HIPPO’.
agriculture
habitat loss
invasive species
pollution
population growth
over harvesting
what is the effect of invasive species
As humans began to move around the planet they carried with them species that were then deposited in ecosystems where they had not existed before. These ‘alien’ species in many instances became ‘invasive’ (the ‘l’ in ‘A HlppO,) when then they adversely affected endemic (native) species by competing with them, leading to a reduction in the population of endemic species.
lnvasive species can lead to the extinction of the native species: for example, in Hawaii many species of endemic snail (Figure ‘10.11) have been wiped out by the introduction of rats to the islands,
overhunting
has led to a significant reduction in population size of many species. Animals are hunted for food, medicines, souvenirs, fashion (e.g. fur coats), and to supply the exotic pet trade. overhunting of North Atlantic cod in the 1960s and 1970s led to a collapse in fish numbers.
what is pollution
Pollution is contamination of the Earth and atmosphere to such an extent that normal environmental processes are adversely affected. Pollutants, that is to say the factors that cause pollution, are disagreeable, toxic and harmful. all pollutants are contaminents but not all contaminants are pollutants
source of pollution:
agriculture
- Fertilizers, manure, silage
Spreading fertilizers on fields; runoff of manure and silage
Eutrophication - Pesticides
Spraying crops
Pesticides build up in food chains and affect the health of animals
-Salinization
lrrigation ( watering crops)
Accumulation of salts in soils kills plants
source of pollution:
manufacturing industry
- solid waste
disposal of by products and waste - toxic spills and leaks
lndustrial dumping and accidents
source of pollution:
Domestic waste
- Solid domestic waste
Waste in landfill sites
Contamination of groundwater; release of methane - Sewage
Waste from toilets; disposable nappies
Eutrophication; reduced oxygen in water; disease
source of pollution:
Transport
- Runoff from roads
Oil leakages; road drainage
Contamination of grou ndwater, streams and soils
The effects of pollution on human health
air pollution
- headache/ fatigue
Nerve damage
Lead
co - respiratory illness
Particulate
matter
Ozone - cardiovascular illness
so2
no2 - cancer, nausea , gastrointestinal
Volatile organic compounds
The effects of pollution on human health
Water pollution
- headache/ fatigue
- cancer, nausea , gastrointestinal
Bacteria
Paraeites
Chemicals
The effects of pollution on human health
soil contamination
- headache/ fatigue
- cancer, nausea , gastrointestinal
- cardiovascular illness
Pesticides
how were fossil fuels formed?
Fossil fuels were formed over millions of years from the remains of dead plants and animals: coal was formed from dead plant material; oil and gas were formed from dead marine organisms. Power stations use fossil fuels as a source of energy - when fossil fuels are burnt they release elements that have been trapped for millions of years back into the atmosphere.
Fossil fuels contain all the elements that were present in
the living organisms from which the fuels were made, i.e. carbon, hydrogen and oxygen (from carbohydrates, lipids and proteins), and nitrogen (from proteins). Some proteins also contain sulfur.
what oxides are produced when fossil fuels are burnt
- Carbon forms carbon dioxide (CO2) and carbon monoxide (CO) (if the fossil fuel is incompletely burnt)
- Nitrogen forms nitrogen oxides (NOx), such as nitric oxide (NO), nitrogen dioxide (NO22) and nitrous oxide (N2O). Their lifespans tn the atmosphere range from one to seven days for nitric oxide and nttrogen dioxide, to 170 years for nitrous oxide.
- Sulfur forms sulfur dioxide.
what Is the function of carbon monoxide
Carbon monoxide combines with hemoglobin in the blood rather than oxygen, meaning that less oxygen reaches respiring tissues. CO is found in fumes produced when fossilfuels are burnt in vehicles, stoves, boilers, fireplaces, gas ranges or furnaces. CO can build up indoors and poison people and animals who breathe it - in high enough concentrations it can kill as it stops sufficient quantities of oxygen form reaching the brain.
how is acid rain formed?
sulfer dioxide ( so2) + nitrogen oxide ( NOx) from factories and burning fossil fuels get released into the atmosphere forming NOx+H2O nitric acid HNO3 and sulfuric acid SO2+H2o=H2SO4 falling as acid particles and gas, acid snow or acid rain.
what is the effect of acid rain on trees
thinning of crown, direct damage to needles, leaves and bark, gas aerosol and particles , decreased resistance in drought/ disease, shedding of leaves and needles, LEACHING: loss of nutrients in the leaves CA and MG
- tree is weaker by lack of nutrients and excess of poisons
fauiler of seedlings = change in organic life
soil acidification: poisonous heavy metals mobilized = reduced intake of water and nutrients= damage to fine root hairs= nutrients washed away= decomposition slowed down= acidification of top soil
explain eutrophication
overuse of fertilizers to improve crop yields has led to pollution of freshwater resources,
- lncreased nitrogen and phosphorus in the water leads to increased algal growth (an ‘algal bloom’) - nitrogen is used by the algae to make protein, and phosphorus is needed to make cell membranes, DNA and other organic molecules of life.
- The algae block light from reaching lower levels in the lake - aquatic plants below the surface of the lake cannot photosynthesize and so die.
- Algae also die - there is a build-up of dead organic material on the bottom of the lake.
- Bacteria feed on the dead organic matter - they need oxygen to respire and so oxygen levels in the lake decrease (the water become ‘anoxic’).
- The lack of oxygen means that animals in the lake, such as fish, die.
