Chapter 21 Flashcards
State how modern technology has resulted in increased food production
– agricultural machinery is used to farm larger areas of land and improve efficiency in time
– chemical fertilisers to improve crop yield
– insecticides to improve quality and crop yield
– herbicides to reduce competition with weeds
– selective breeding to improve production by crop plants and livestock, e.g. cattle, fish and poultry
Describe the negative impacts to an ecosystem of large-scale monocultures of crop plants
- Herbicides and pesticides kill plant and insect species that are harmless and can even help the plant
- continous use of these chemicals act as selective agents, resulting in evolution of resistance on weeds, pests and pathogens.
- large scale use of chemical fertilisers can reduce the structure of the soil so it can no longer support biodiversity of soil organisms.
Describe the negative impacts to an ecosystem of intensive livestock production
- a lot of animals in a place can produce a lot of methane which acts as a greenhouse gas.
- the urine and faeces from these animals can be passed to rivers and lakes which causes eutrophication
- waste food from fish farms has serious effects on the surrounding waters
- high densities of fish means pathogens can spread quicker and using pesticides and antibiotics can cause resistance problems
Discuss the social, environmental and economic implications of providing sufficient food for an increasing human global population
Food production requires a lot of land. This means large groups of people have to be displaced from their homes. Using machines to work these farms means rural unemployment. Intensive farming requires a lot of energy which can come from fossil fuels and it requires a lot of investment by big companies which could have gone to the locals.
Discuss the problems which contribute to famine including unequal distribution of food, drought and flooding, increasing population and poverty
Poorer countries do produce enough food for their population, but they need to sell it to other nations to gain foreign currency. Drought and flooding can cause these crops to fail meaning less food but it is mostly due to the lack of transportation of food to people who need it. This may be due to war.
Describe the reasons for habitat destruction
– There is an increased area need for food crop growth, livestock production and housing, so habitats get destroyed to make room.
– extraction of natural resources; digging mines and quarries for the extraction of coal and minerals can destroy the surrounding area/ habitat
– marine pollution; major pollutants such as fertilisers (eutrophication), industrial chemicals and oil from oil ships can damage coral reefs and kill the marine population.
How can humans have negative impacts on habitats?
through altering food webs and food chains
List the undesirable effects of deforestation
It causes habitat destruction, extinction of species, loss of soil, flooding and an increase of carbon dioxide in the atmosphere
Explain the undesirable effects of deforestation on the environment
Soils in certain places are very thin and when the vegetation is removed the soil is easily washed away causing soil erosion, gullies and loss of plant nutrients. Flooding happens more frequently as water runs off the land much quicker and is not absorbed by plants and transpired into the atmosphere. Carbon dioxide is released into the atmosphere as more vegetation is burned and there are less plants to absorb the CO2 for photosynthesis. Habitat destruction by cutting down trees has led to the extinction of species yet to be found and classified.
State the sources and effects of pollution of land and water, e.g. rivers, lakes and the sea
insecticides - It comes from arable and livestock agriculture. It effects the land as it accumulates in food chains; kills harmless species. Can buildup in some shellfish.
herbicides - It comes from arable agriculture and spray drifts kill harmless plants; persist into the environment
nuclear fall-out - It comes from atomic bombs, accidents at nuclear power stations; nuclear tests and it causes death with high exposure; cancers in humans; mutations in non-human species. Radioactive chemicals are found in higher concentrations around costal nuclear power stations.
State the sources and effects of pollution of water (rivers, lakes and the sea)
chemical waste - It is produced by factories and can be fatal to wildlife and humans; can accumulate in humans
discarded rubbish - contains many harmful chemicals that leach from rubbish dumps into the ground. Toxic metals in rubbish can harm marine life.
untreated sewage - It comes from human and livestock waste such as urea, ammonia, protein, carbohydrates, fats and pathogens. It reduces oxygen concentration in rivers and the destruction of freshwater communities
fertilisers - comes from arable agriculture and causes eutrophication in fresh water.
Explain the process of eutrophication of water
- Fertilisers are washed from fields into the waterways by rain. This brings an excess of nutrients into the habitat.
- The nutrients cause plants to grow rapidly, and there is an algae bloom across the surface.
- Algae covers the surface of the water, preventing sunlight from passing through. This means that plants cannot photosynthesise to produce energy so they begin to die.
- As there are less plants to photosynthesise, less oxygen is released into the water. The dead plants are broken down by decomposers, which use up the remaining oxygen from the water.
- The lack of oxygen causes organisms such as fish to die, reducing the biodiversity of the habitat.
Discuss the effects of non-biodegradable plastics in the environment, in both aquatic and terrestrial ecosystems
Non-biodegradable plastics take up a lot of space and can harm nearby animals in the area. Sea life can also swallow the plastic and get sick or even die and some can get entangled in the plastic.
State the sources and effects of pollution of the air by methane and carbon dioxide
Methane comes from the decomposition of vegetation inside or outside organisms such as cows. Carbon dioxide comes from respiration and burning of fossil fuels. These two gases in the atmosphere cause an enhanced greenhouse effect and climate change as they trap the heat of the sun making the earth hotter.
Discuss the causes and effects on the environment of acid rain
Acid rain is caused by nitrogen oxides dissolving in rain water to form nitric acid, and sulphur dioxide dissolving to make sulphuric acid. Acid rain then falls and accumulates in bodies of water and soils, causing a change in pH. This can make mineral ions for plants in the soil to wash away and cause the release of aluminium from the sea bed which is toxic to fish. The acid also corrodes infrastructure and damages tree bark and leaves.
