21. Human Influences on Ecosystems Flashcards
1
Q
What has increased food supply?
A
Modern technology
2
Q
In what 4 ways has modern technology helped increase food supply?
A
- agricultural machinery
- chemical fertilisers
- insecticides and herbicides
- selective breeding
3
Q
How has agricultural machinery helped increase food supply?
A
Agricultural machinery has replaced humans and improved efficiency due to the ability to farm much larger areas of land
4
Q
How have chemical fertilisers helped increase food supply?
A
Chemical fertilisers improve yields – fertilisers increase the amount of nutrients in the soil for plants, meaning that they can grow larger and produce more fruit
5
Q
How have insecticides and herbicides helped increase food supply?
A
Insecticides and herbicides – these chemicals kill off unwanted insects and weed species, meaning that there is less damage done to plants and fruit lost to insects (insecticides), as well as reducing competition from other plant species (herbicides)
6
Q
How has selective breeding helped increase food supply?
A
Selective breeding – animals and crop plants which produce a large yield are selectively bred to produce breeds that reliably produce high yields
7
Q
What is monoculture?
A
Monoculture farming means that on a given area of agricultural land only one type of crop is grown (eg trees for palm oil grown in Indonesian rainforest)
8
Q
What is a problem with monoculture relating to biodiversity?
A
This large scale growth of a single variety of plant does not happen naturally in ecosystems, where there are usually many different species of plants growing which, in turn, support many species of animals (high biodiversity)
In monocultures, biodiversity is much lower
9
Q
What is a problem with monoculture relating to pests?
A
Another issue with monocultures is the increase in pest populations – if a particular pest feeds on a crop, farming it in large areas repeatedly means there is an ample supply of food for the pest, causing the population to increase
10
Q
What is a problem with monoculture relating to insecticides?
A
Often farmers will spray insecticides onto crops in order to control the pests. This leads to:
harmless insects being killed as well
pollution by pesticides (which are often persistent chemicals which accumulate in food chains)
in many instances where they are used repeatedly for specific pests, the pests may eventually become resistant to them, reducing their effectiveness
11
Q
What is a problem with farming livestock In developed countries?
A
In developed countries, large numbers of livestock are often kept in an area that would not normally be able to support more than a very small number
12
Q
What are these livestock given which is harmful?
A
They are often
- fed high energy foods,
- regularly given medication such as antibiotics as a preventative measure against disease and
- kept in artificially warm temperatures and small spaces that do not allow for much movement
13
Q
What are 3 ecological issues involved with intensive farming?
A
- reduction in biodiversity in areas where large amounts of land are used to graze cattle (as only grass is grown so in effect it becomes a monoculture)
- overgrazing can lead to soil erosion
- large numbers of cattle produce large amounts of methane, a greenhouse gas
14
Q
When does a famine occur?
A
When people do not receive enough food, famine occurs
15
Q
What can cause a famine? (4)
A
- natural disasters, such as drought and flooding,
- increasing population,
- poverty, and
- unequal food distribution
16
Q
What has to happen to food production as population increases?
A
As the global human population increases, food production must also be increased to support the increasing population
17
Q
Why is it bad that the food production industry has to keep increasing?
A
This is a problem as more land is required to grow crops and animals, meaning that deforestation is happening at an increasing rate, and there is also an increasing amount of greenhouse gases emitted from animal production
18
Q
Why is an accumulation of greenhouse gases a problem?
A
Greenhouse gases cause global warming, which is a worldwide issue that leads to increased natural disasters, such as tropical storms and drought, as well as rising sea levels, which floods homes and decreases the amount of habitable land
19
Q
What is the increasing human population doing in relation to habitats?
A
The increasing human population of the planet is causing destruction of many habitats from rainforest to woodland to marine
20
Q
How can habitats be destroyed?
A
Many habitats are destroyed by humans to make space for other economic activities, or by pollution from these activities, and this reduces the biodiversity of these areas
21
Q
Why is it harmful when habitats are destroyed?
A
This interrupts food chains and webs, meaning that more species may die because their prey is gone
22
Q
What are the 3 main reasons for habitat destruction?
A
- clearing land for farming and housing
- extraction of natural resources
- marine pollution
23
Q
How does clearing land for farming and housing contribute to habitat destruction?
A
- crops, livestock and homes all take up a large amount of space
- as there is an increasing population and demand for food, the amount of land available for these things must be increased by clearing habitats such as forests (deforestation)
24
Q
How does extraction of natural resources contribute to habitat destruction?
A
- natural resources such as wood, stone and metals must be gathered to make different products.
- therefore many trees are cut down, destroying forest habitats. in addition, some resource extraction takes up a large amount of space
- for example: mining, which means that the land must be cleared first
25
How does marine pollution contribute to habitat destruction?
- human activities lead to the pollution of marine habitats
- in many places, oil spills and other waste pollutes the oceans, killing sea life
- in addition, eutrophication can occur when fertilisers from intensively farmed fields enters waterways
- this causes a huge decrease in biodiversity in these areas as most aquatic species living in these waterways die from lack of oxygen
26
What is deforestation?
Deforestation is the clearing of trees (usually on a large scale)
27
How can deforestation be a sustainable practice?
If trees are replaced by replanting it can be a sustainable practise
28
Why does deforestation usually occur?
Generally the trees are being cleared for the land to be used in a different way (for building, grazing for cattle, planting of monocultures such as palm oil plantations etc) and therefore it is not sustainable
29
What is a particularly severe example of habitat destruction?
As the amount of the Earth’s surface covered by trees decreases, it causes increasingly negative effects on the environment and is a particularly severe example of habitat destruction
30
What are 4 undesirable effects of deforestation?
Undesirable effects of deforestation include:
Extinction of species
Loss of soil
Flooding
Increase of carbon dioxide in the atmosphere
31
How is extinction of species an undesirable effect of deforestation?
- forest habitats, especially tropical rainforest s, have a huge range of biodiversity and as habitat is destroyed it causes the loss of large numbers of plant and animal species
- many of these species are only found in these areas therefore will become extinct
32
How is loss of soil an undesirable effect of deforestation?
- tree roots help to stabilise the soil, preventing it from being eroded by rain
- trees will usually take up nutrients and minerals from the soil through their roots
- without trees, nutrients and minerals will remain unused in the soil so will be washed away into rivers and lakes by rain (leaching)
- this loss of soil nutrients is permanent and makes it very difficult for forest trees to regrow, even if the land is not cultivated with crop plants or grass for cattle
33
How is flooding an undesirable effect of deforestation?
- without trees the topsoil will be loose and unstable so will be easily washed away by rain, increasing the risk of flash flooding and landslides
34
How is increase of carbon dioxide in the atmosphere an undesirable effect of deforestation?
- trees carry out photosynthesis during which they take in carbon dioxide and release oxygen
- the removal of significant numbers of trees means less carbon dioxide is being removed from the atmosphere (and less oxygen released)
- when areas of land in forests are cleared for land use, the trees are of ten burned as opposed to being cut down. this releases carbon dioxide (it is an example of combustion), further increasing carbon dioxide levels in the atmosphere and contributing to global warming
35
What types of pollution have human activities caused?
Human activities have led to the pollution of land, water and air
36
What sources can pollution come from?
- industry and manufacturing processes,
- waste and discarded rubbish, - chemicals from farming practices,
- nuclear fall-out,
- untreated sewage
37
What is the source/cause for untreated sewage?
lack of sewage treatment plants in inhabited areas due to poor infrastructure lack of money meaning sewage runs / is pumped into streams or rivers
38
What is the source/cause for chemical waste?
chemicals such as heavy metals ike mercury can be released from factories into rivers and oceans or leach into land surrounding the factories
39
What is the source/cause for discarded rubbish?
much rubbish consists of plastic that is either discarded or buried in landfills
40
What is the source/cause for fertilisers?
runoff from agricultural land applied in too high concentration
41
What is the source/cause for insecticides and herbicides?
sprayed on crops to prevent damage by insects and growth of weeds
42
What is the source/cause for nuclear fallout?
radioactive particles that get into the environment from accidental leakage from nuclear power plants or explosion of a nuclear bomb
43
What is the source/cause for methane?
cattle farming, rice fields, landfills
44
What is the source/cause for carbon dioxide?
produced when fossil fuels are burnt, also released when trees are burnt to clear land for human use
45
What is the effect of untreated sewage on the environment?
provides a good source of food for bacteria which increase rapidly, depleting the oxygen dissolved in the water (as they respire aerobically) and causes death of aquatic organisms such as fish- known as eutrophication
46
What is the effect of chemical waste on the environment?
many heavy metals and other chemicals are persistent- they do not break down and so can build up in food chains (known as bioaccumulation), poisoning the top carnivores
47
What is the effect of discarded rubbish on the environment?
much rubbish, such as that made from plastic, is non-biodegradable and remains in the environment for hundreds of years. animals also eat the plastic as it breaks into smaller pieces (especially in the ocean) and it can get into food chains this way
48
What is the effect of fertilisers on the environment?
causes algal blooms which then die and provide a good source of food for decomposing bacteria which increase rapidly, depleting the oxygen dissolved in the water as they respire aerobically) and causing death of aquatic organisms such as fish known as eutrophication
49
What is the effect of insecticides and herbicides on the environment?
bioaccumulation, loss of biodiversity, damage to beneficial insects. can build up in soil to toxic concentrations and harm other organisms
50
What is the effect of nuclear fallout on the environment?
some radioactive particles have long half-lives and can remain in the environment for many years. they can cause increased risks of cancer and smaller particles can be carried by winds hundreds of miles from the original site of exposure
51
What is the effect of methane on the environment?
methane is a greenhouse gas which contributes to the enhanced greenhouse effect that is causing climate change
52
What is the effect of carbon dioxide on the environment?
carbon dioxide is a greenhouse gas which contributes to the enhanced greenhouse effect that is causing climate change
53
Why do plastics have such a negative impact on the environment?
Plastics have a large negative impact on both land and water habitats due to their non-biodegradability
54
1. What effects does plastic have on animals in marine habitats?
- Animals often try to eat plastic or become caught in it, leading to injuries and death
55
2. What can plastic release as it breaks down?
As the plastic breaks down it can release toxins that affect marine organisms
56
3. How can plastic enter the food chain?
Once it has broken down into very small particles, it is commonly ingested by animals and enters the food chain
57
How is plastic usually disposed of?
Plastic is generally disposed of by burying in landfills
58
Why is it harmful to dump plastic in landfills?
As it breaks down, it releases toxins into the surrounding soil and as such the land is no good for growing crops or grazing animals and can only be used for building on several decades after burial
59
What chemical substance can be harmful if it reaches a water supply?
Female contraceptive hormones are excreted from the body in urine and then make their way into the water supply, as they are not filtered out by sewage treatment plants
60
What can female contraceptive hormones cause, in aquatic environments?
If they reach male aquatic organisms, such as fish and frogs, which are very sensitive to the hormones, it causes feminisation
61
What is feminisation?
This is where male organisms begin to produce eggs and lose the ability to reproduce
62
Why is feminisation harmful to aquatic organisms?
Consequently, a smaller amount of offspring is produced which can harm the species survival and also disrupts food chains for animals that usually feed off these organisms
63
How can feminisation be harmful to humans?
In addition, these hormones can reduce the sperm count in human males, which causes fertility problems
64
1. What is the first stage of eutrophication? What goes where and what does this cause?
Runoff of fertiliser from farmland enters the water and causes increased growth of algae and water plants
65
2. Why is algal bloom harmful?
eutrophication
The resulting ‘algal bloom’ blocks sunlight so water plants on the bottom start to die, as does the algae when competition for nutrients becomes too intense
66
3. What can happen when lots of aquatic organisms die at once, as a result of eutrophication?
eutrophication
As water plants and algae die in greater numbers, decomposing bacteria increase in number and use up the dissolved oxygen whilst respiring aerobically
67
4. What may be a result of a large amount of bacteria respiring aerobically in a pond?
eutrophication
As a result there is less oxygen dissolved in water, so aquatic organisms such as fish and insects may be unable to survive
68
What creates sulfur dioxide?
Combustion of fossil fuels that contain sulfur impurities creates sulfur dioxide
69
How is sulfur trioxide created?
Sulfur dioxide is released into the atmosphere where it combines with oxygen to form sulfur trioxide
70
What forms acid rain?
Sulfur trioxide dissolves in water droplets in clouds and forms acid rain
71
What gases can cause acid rain?
- sulphur dioxide
| - oxides of nitrogen
72
What release sulphur dioxides and oxides of nitrogen into the air?
- burning of fossil fuels
| - combustion of petrol in car engines
73
What are 5 effects of acid rain?
1. Damage to leaves, killing plants
2. Acidification of lakes, killing animals
3. Increased risk of asthma attacks and bronchitis in humans
4. corrosion of stonework on buildings
5. release of aluminium from the soil into lakes that are toxic to fish
74
What are 3 possible solutions for acid rain?
1. changing the power stations from coal and oil to renewable energy sources
2. using 'scrubbers' in power station chimneys to remove sulphur dioxide
3. using catalytic converters in car exhausts to convert oxides of nitrogen to harmless nitrogen
75
What is a greenhouse gas?
A greenhouse gas is a gas that absorbs infrared radiation from the Sun so it remains trapped in the Earth’s atmosphere
76
Why are greenhouse gases important?
This is important to ensure Earth is warm enough for life
77
Why are high levels of greenhouse gases dangerous?
however if levels of these gases in the atmosphere increase it leads to an increase in the greenhouse effect which causes the Earth’s average temperature to rise
78
What are 5 examples of greenhouse gases?
- Water vapour
- Carbon dioxide
- Methane
- Nitrous oxides
- CFCs
79
1. What is emitted from where that enters the earth's atmosphere?
(greenhouse effect)
The Sun emits rays that enters the Earth’s atmosphere
80
2. What happens to the suns rays once they enter the earth's surface? (3 options)
(greenhouse effect)
1. The heat bounces back from the Earth’s surface
2. Some heat is reflected back out into space
3. Some heat is absorbed by greenhouse gases and is trapped within the Earth’s atmosphere – this is normal
81
3. What can the greenhouse effect cause and how?
However, as the levels of greenhouse gases in the atmosphere rise due to human activities the Earth’s average temperature rises beyond normal (an enhanced greenhouse effect), causing global warming or climate change
82
What are 6 consequences of global warming due to an enhanced greenhouse effect? (brief)
- ocean temperatures increase
- extreme weather
- loss of habitats
- decrease in biodiversity
- increase in migration of species
- spread of pests and disease
83
Why is it bad if ocean temperatures increase?
Ocean temperatures increase which causes melting of polar ice caps / rising sea levels / flooding / coral bleaching
84
What causes extreme weather and what are examples?
Increasing temperatures can cause extreme weather like super storms, flooding, droughts
85
What can extreme weather events cause?
These extreme weather events can lead to changes in or loss of habitats
86
How can global warming lead to a decrease in biodiversity?
This means that there will be a decrease in biodiversity as food chains are disrupted and extinction rates increase
87
What is a sustainable resource?
A sustainable resource is one which is produced as rapidly as it is removed from the environment so that it does not run out
88
What are examples of non-renewable resources and why?
Some resources, such as fossil fuels (coal, oil and natural gas), are non-renewable because what we use cannot be replaced
89
What do we need to do in order not to run out of fossil fuels?
These resources, once used, cannot be produced anymore and so they need to be conserved by reducing the amount we use and finding other, sustainable resources to replace them
90
How are fossil fuels used? 2
Fossil fuels are being used as an energy source in increasing amounts
In addition, they are the raw materials for many other products we make
91
What substances are made from fossil fuels?
almost all plastics that are made start with oil as a raw material
92
What substances can be reused and recycled?
Some products, especially those made from paper, plastic, glass or metal, can be reused and recycled
93
Why is reusing and recycling substances good?
this reduces waste in the environment and reduces the amounts of raw materials and energy needed to make new products
94
What resources can be maintained and how does this help with sustainability?
Some resources, such as forests and fish stocks, can be maintained – enabling us to harvest them sustainably so that they will not run out in the future
95
What is sustainable development?
Sustainable development is defined as development providing for the needs of an increasing human population without harming the environment
96
What is the problem with sustainable development?
When developing the way in which we use resources to manage them sustainably, we have to balance conflicting demands
97
What 3 conflicting aspects need to be taken into account when trying to develop sustainably?
- needs of local people vs large companies
- needs of Human Resources vs needs of animals and plants
- needs of the current and future population
98
What are the conflicting demands of local people vs large companies?
the need for local people to be able to utilise the resources they have in their immediate environment with the needs of large companies to make money from resources such as forests and fish
99
What are the conflicting demands of Human Resources vs animals and plants?
the need for balancing the needs of humans for resources with the needs of the animals and plants that live in the areas the resources are taken from (preventing loss of habitat and extinction)
100
What are the conflicting demands of current vs future population?
for example if we harvest all the fish we need to feed people now, this might lead to overfishing which would deplete stocks for future generations
101
What is very important for development to occur sustainably?
For development to occur sustainably, people need to cooperate at local, national and international levels in the planning and management of resources
102
What supplies can forests provide? 2
Forests are needed to produce paper products and provide wood for timber
103
Where is most of the world's paper produced?
Much of the world’s paper is now produced from forests which replant similar trees when mature trees are cut, ensuring that there will be adequate supply in the future
104
What types of wood takes a long time to grow and why are they so desirable?
Tropical hardwoods such as teak and mahogany take many years to regrow but are highly desirable for furniture
105
How has using growing wood for timber become more sustainable? (industrial)
Using these types of wood has now been made more sustainable due to the introduction of several schemes designed to monitor logging companies and track the wood produced (eg the Forestry Stewardship Council)
106
How has using growing wood for timber become more sustainable? (societal)
Education helps to ensure logging companies are aware of sustainable practices and consumers are aware of the importance of buying products made from sustainable sources
107
What 3 factors need to be controlled in order to control fish stocks sustainably?
- Controlling the number of fish caught each year (quotas)
- Controlling the size of fish caught
- Controlling the time of year that certain fish can be caught
108
Why does the size of fish caught need to be monitored?
to ensure there are enough fish of a suitable age for breeding remaining
109
Why does the time of year the fish are caught need to be monitored?
to prevent large scale depletion of stocks when fish come together in large numbers in certain areas to breed
110
What 2 other factors are important in order to control fish stocks sustainability?
- restocking
| - educating fisherman
111
How does restocking help to sustain fish stocks?
breeding and keeping offspring until they are large enough to survive in their natural habitat then releasing
112
How does educating fishermen help to sustain fish stocks?
Educating fishermen as to local and international laws and consumers so they are aware of types of fish which are not produced sustainably and can avoid them when buying fish
113
1. What does the demand increase for as the human population increases?
sewage
As human population grows, the need for fresh water increases
114
2. Where does a significant amount of water we consume go?
sewage
A significant amount of water we consume is used to flush away human waste (sewage) into pipes
115
3. Where do the pipes carry the sewage to?
sewage
The pipes carry the sewage and water to treatment plants
116
4. What happens in treatment plants?
sewage
the organic waste is removed and the water cleaned so it can be returned to natural water sources without causing eutrophication
117
5. Where is crude sewage passed through and what does this do?
sewage
Crude sewage flows through a screen in which large materials like paper and sticks are trapped so they can be removed and burned
118
6. Where is the sewage passed though after screening?
sewage
The sewage is passed slowly through channels where grit and other heavy particles picked up along the way settle to the bottom
119
7. What happens to the grit that settles along the bottom of the channel?
sewage
the grit is later washed and returned to the land
120
8. Where do the channels lead to?
sewage
The channels lead into sedimentation tanks
121
9. What happens in sedimentation tanks?
sewage
the solid material settles on the bottom as sludge and the liquid part, called effluent, remains on top
122
10. What happens to the sludge?
sewage
The sludge is removed by pumping it into tanks where anaerobic bacteria decompose it
123
11. What do the bacteria in the tanks produce and what is done with this?
sewage
often the bacteria produce methane which can be collected and used as an energy source for the plant
124
12. What is the effluent treated with? What does this do?
sewage
The effluent (liquid) is treated with aerobic bacteria to remove any organic waste in it
125
13. What is added to the effluent once it is treated with aerobic bacteria? What does this do?
sewage
treated with chlorine to kill the bacteria
126
14. After being treated with chlorine, where does the effluent go?
sewage
At this point it is clean enough to return to natural water systems or be passed on to a second treatment plant where it is processed further to make it pure enough to reuse as drinking water
127
What are endangered species at risk of?
An endangered species is at risk of becoming extinct
128
What does it mean if a species is endangered?
the population of the species may fall below a critical level
129
What 5 factors may cause a species to become endangered?
```
hunting
climate change
pollution
loss of habitat
introduction of non-native species that outcompete native species
```
130
What 4 conservation measures can endangered species be helped by?
- education programmes
- captive breeding programmes
- monitoring and legal protection of the species and of their habitats
- seed banks
131
What are seed banks? What do they store and why?
seed banks as a conservation measure for plants – seeds of endangered plant species are carefully stored so that new plants may be grown in the future
132
What may cause a species to be at risk of extinction, biologically speaking?
A species may be at risk of becoming extinct if there is not enough genetic variation in the population
133
Why is a lack of genetic variation a cause of extinction?
as random changes in the environment may quickly cause extinction because the remaining organisms are all very similar and may not have the adaptations to survive such changes
134
What is a moral reason for conservation programmes?
reducing extinction rates of both plant and animal species
135
What is a cultural reason for conservation programmes?
keeping damage to food chains and food webs to a minimum and protecting vulnerable ecosystems (eg the rainforests)
136
What is a scientific reason for conservation programmes?
protecting our future food supply and maintaining nutrient cycles and possible sources of future medical drugs and fuels
