Chapter #19 - Human Influences On The Enviornment Flashcards
1
Q
How has food production changed over time?
A
In the past few hundred years, food production has greatly increased. Of course, we must increase food production to feed our growing population.
2
Q
Why has food production increased?
A
- Agricultural machinery
- Agricultural chemicals
- Selective breeding
- Monocultures
3
Q
How has agricultural machienery increased food production?
A
Development of machinery like tractors and combine harvesters allow farmers to cultivate a larger area of land in a smaller amount of time.
4
Q
What are the different types of agricultural chemiclas?
A
- Chemical fertilisers
- Insecticides
- Herbicides
5
Q
Why would agricultural chemiclas be used?
A
Farmers use chemicals to improve crop growth, to get more yield from the same area of ground.
6
Q
How do chemical fertilisers increase food production?
A
add more mineral ions (eg. Nitrate) to soils
7
Q
How do insecticides increase food production?
A
are sprayed onto crops to kill insect pests that may reduce yields or make the crop look less appealing to buyers.
8
Q
How do herbicides increase food production?
A
are sprayed to kill weeds, which compete with crops for space and therefore limit their growth.
9
Q
Why does selective breeding
A
- Farmers carefully select plants and animals to create new varieties which produce greater yields.
- E.g. Modern wheat varieties produce far more grain per plant than older ones did.
- Selective breeding has produced plants that can grow in poor soils, or are resistant to disease.
- Cattle now produce more meat / milk than they did in the past
- Hens lay more eggs
10
Q
Monoculture
A
an area of ground covered by a single crop, with almost no other species present. (often used in developed countries)
11
Q
What are the advantages of monocultute?
A
- They make sowing, tending, harvesting and sellingmore efficientfor the farmer because:
- Using machinery to tend to a large area of land is faster & more efficient than tending multiple small separate fields.
- A uniform crop is more likely to grow to the same height and ripen at the same time (can be harvested all at once with machinery).
- A large monoculturecan be treated with the same herbicides/pesticides in the same way at the same time.
- A monoculture will producelarge quantities of seeds, fruit, etc. that are all similar in size and quality = easier to sell.
12
Q
What are the main disadvantages of monocultures?
A
- Reduction of biodiversity (the number of different species that live in an area)
- Increase in pests that thrive on large supply of food.
- Reduction in soil fertility
13
Q
How is reduction of biodiversity a disadvantage of monoculture?
A
Only a few species can live where the crop is growing. In natural ecosystems, there are usually manydifferent species (high biodiversity).
14
Q
How is an increase in pests a disadvantage of monoculture?
A
- Increase in pests that thrive on large supply of food.
-
E.g. Leafhoppers feed on rice plants (reducing yields).
-They alsotransfer plant viruses to the rice – spreading disease.
-If a large areahas onlyrice plants,the leafhopper population will thrive.
-Farmers can use pesticides, but this is expensive and kills other insects which are not threats (including those that prey on leafhoppers!)
In many places, leafhoppers have become resistant to insecticides.
-Some farmersgrow rice plants in small sections to try to avoid this.
15
Q
How is a reduction in soil fertility a disadvantage of monocolture?
A
- Farmers often grow the same crop on the same land, year after year.
- The crop plants all need the same mineral ions, so they are depleted from the soil.
- Farmersneed to constantly use fertiliser.
- Or…. grow a mix of different crops / at different times of the year to maintain a mineral balance
16
Q
What are the main methods of livestock production?
A
- extensive livestock production
- intensive livestock production
17
Q
How does intensive livestock production work?
A
large numbers of animals are kept in a relatively small area (common in developed countries).
* Farmers use: high energy food to feed animals
* Farmers regularly use medication to stop disease development
* Animals kept in temperature-controlled buildings to maximise growth
18
Q
How does extensive livestock production work?
A
livestock are kept outside, they graze on grass or are brought cut vegetation to eat. The livestock don’t take too much from the environment, and don’t do too much damage.
19
Q
What are the advantages of intensive farming/ livestock production?
A
- It can help provide more food to people, often at a lower price
- Therefore fewer people go hungry (including those in poverty)
- It takes up less space (land), and therefore perhaps habitats for other species.
20
Q
What are the disadvantagesto intensive farming
A
- Welfare issues for animals suffering in crowded conditions.
- Disease can spread easily among animals.
Insome countries this is dealt with by using a lot ofantibiotics – therefore there is opportunity for antibiotic resistance. - The waste from intensive farming can pollute land and waterways.
Welfare issues for animals suffering in crowded conditions. - Disease can spread easily among animals.
Insome countries this is dealt with by using a lot ofantibiotics – therefore there is opportunity for antibiotic resistance. - The waste from intensive farming can pollute land and waterways.
- Large quantities of watermust be provided. Sometimes thistakeswater from surrounding environment (affecting local species)
21
Q
How are habitats destroyed?
A
- Deforestation
- Mining for minerals
- Polluting
- Removal of species
22
Q
How are habitats destroyes through deforestation?
A
We cut down vegetation to use the land for farming/building houses/roads. (Deforestation)
23
Q
How are habitats destroyed through mining?
A
We damage habitats through mining for materials like metal ores, sand, gravel, fossil fuels.
The mine destroys the habitat by removing soil & vegetation
And water flowing away from the mine can be toxic. It can enter soil & rivers
24
Q
How are habitats destroyed by polluting?
A
We add pollutants to land and water, that kill organisms living there and therefore change the habitat.
25
Give an example of how habitats are destroyed when key species are removed.
Collecting live corals from coral reefs endangers the whole ecosystem.
Corals contain tiny photosynthetic algae, which are the start of every food chain on a coral reef.
26
Deforestation
the cutting down of large numbers of trees
27
Why do humans do defprestation>
* Use wood for fuel
* Use wood for building
* Use land for agriculture
28
What are is the concequence of rainforest deforestation?
* can lead to species extinction if there is not enough habitat / resources for the species to reproduce.
* soil erosion
* water cycle dissruption
* social economics and politics
29
What is special about rainforests?
Rainforests are places with extremely high biodiversity. Many species living in one place.
30
What is the process and concequence of soil erosion?
* When rainforest is cut down, the soil under the trees is exposed to rain.
* The soil in rainforests is thin, and therefore quickly washes away. Especially without plants roots to help it bind together.
* This soil erosion makes it very difficult for the rainforest to grow back again.
* The soil can be washed into rivers, filling them with soil and causing flooding.
31
What is the process and concequence of chnages in the water cycle due to deforestation?
* Trees use a lot of rainwater to take up by their roots and eventually transpire.
* If trees are gone, the rain runs off the soil and into rivers – much less goes back into the atmosphere as water vapour.
* Air becomes drier = less rain falls = people struggle to grow crops
32
What is a factor that prevents deforestation from being dtopped/
**Social economics & politics**
* Most tropical rainforests are in developing countries, some of which where people are generally poor.
* Cannot expect someone who is poor yet needs to produce food to feed their family not to clear land for agriculture.
… unless you can offer an alternative, which is what some charities and NGOs aim to do (provide options for other sources of food production and income)
*In some places, the government may be the main driver behind deforestation. (lobbying)*
33
Pollution
adding something to the enviornment that harms it.
34
What are the sources of pollution?
* greenhouse gases and climate change
* Eutrophication
* Plastics
35
Greenhouse gases
gases such as carbon dioxide and methame that trap heat within the atmosphere.
36
The greehouse effect
the heating effect on the Earth of trapping heat by greenhouse gases. Note: this is natural and useful, without it Earth would be too cold for any life.
37
How does the greenhouse effect occure?
1. CO2 allows shortwave radiation from the sun to pass through the atmosphere.
2. It is absorbed by the ground and emits longer wavelength, infrared radiation.
3. CO2 does not let all of this type of radiation pass through, therefore much of it is trapped in our atmosphere.
38
What is ir called when greenhouse gas levels are increasing more?
enhanced greenhouse effect - more pf the long wave radiation is trapped by the atmostphere - so climate is changing.
39
What are the sources of GHGs?
* increased use of fossil fuels
* Deforestation
* Methane
40
Why is there an increase in use of fossile fuels?
Because of the industrial revolution (fuel for cars, trains, planes).
41
Why is deforestation a source of GHGs?
leaves fewer trees to remove CO2 from the atmosphere. Also, combustion of wood.
42
Why is methane a source of GHGs?
Methane is produced by farming. It is released by bacteria that break down organic matter in:
* The mud of rice paddies
* The stomachs of animals that chew cud (cows, sheep)
* Some insects
* Methane is also produced by decomposers in decaying rubbish and landfill sites.
43
What are possible ways to reduce methane emissions? (Solutions)
* Throwing away less rubbish
* Collecting methane to use for fuel (burning methane does release CO2 but it has less of an effect on trapping heat in our atmosphere than methane does)
44
What is the concquence of increasing methane levels in the atmostphere?
As the concentration of CO2 and methane increases, the mean temperature on earth increases.
45
What are the effects of the enhanced greenouse effect?
* Sea levels rising
* More Extreme Weather Events
46
What are the concequences of sea levels rising?
* ice caps in the Artic and Antartica melting
* Thermal expansion - as the temp of a liquid increases, its volume increases.
47
How does a higher temperature cause more extreme weather events?
more energy in the atmosphere. This can lead to different wind patterns and weather systems.
48
What are the concequences of more extreme weather events?
* stronger hurricains and cyclones
* droughts happens more aften and last longer (can cause forest fires and affect wildlife)
* greater rainfall and flooding
* too many variables for scientists to fully understand/predict this
49
Solutions to enhanced greenhouse effect
Obviously --- reducing GHG emissions
50
What actions are bing made to reduce GHGs emissions?
* Agreements have been made by countries to try to do this, but they are difficult to implement.
* Many countries are moving towards renewable energy (eg, wind and solar), but still some countries rely heavily on coal.
51
How do many aquatic organisms carry out aerobic respiration?
They use dissolved oxygen in the water.
52
What substances can pollute water and what does this cause (vauge)?
Fertilizers and untreated sewage: can reduce the amount of dissolved oxygen in water
**also...**
slurry from farm animals, or from pits where grass is rotted to make silage
53
What is leaching?
The process by which rainwater carries unused fertilizer from fields into nearby water bodies.
54
Eutrophication
a chain of events caused by the addition of extra plant nutrients to water, resulting in a decrease in the concentration of dissolved oxygen available for organisms that require it for aerobic respiration.
55
Detail the process of eutrophication - due to fertilizers
1. Fertilizers contain nitrates and phosphates (that help plants grow)
2. When these ions enter water, the algae and green plants grow more.
3. This may cover the water, blocking out light from lower levels.
4. Plants at lower levels may die.
5. Decomposer bacteria benefit from all of the producers dying.
6. The bacteria breed rapidly.
7. More bacteria = more respiration = more dissolved oxygen used up.
8. Soon there is very little oxygen
left for other organisms (eg. fish)
56
Detail eytrophication in general?
1. Farmers use fertilisers containing nitrate (soluble) and phosphate ions to encourage crop growth
2. Rain causes fertilisers to leach into lakes and rivers (leaching = carrying of fertilizer into rivers)
3. Fertiliser encourages algae growth (algal bloom), which form a thick layer on the surface of the water
4. Producers (plants) at the bottom of the lake/river do not receive sunlight and die
5. There is increased decomposition, decomposers (e.g. bacteria) use up more oxygen due to increased respirtion.
6. Not enough oxygen levels in the water due to decomposition so fish and all organisms die due to lack of oxygen
57
Slurry
A cause of eutrophication from farm animals or from pits where grass is rotted to make silage.
58
What substances are found in untreated sewage?
Faeces, urine, detergents, etc.
59
What happens when untreated sewage enters a water body?
It provides a good food source for aerobic bacteria.
60
Does untreated sewage cause algae to grow?
No, it supports bacteria, not algae growth.
61
What effect does the increase in aerobic bacteria have on the water?
Bacteria population grows, oxygen levels decrease.
62
What is the term for the process where oxygen levels drop due to increased bacterial activity?
Eutrophication
63
What are some solutions to reduce the effects of eutrophication?
64
Why should sewage be treated before being released into the environment?
To prevent nutrients and pollutants from causing eutrophication.
65
Why is it unrealistic to completely stop using fertilizers?
Because they help produce more food and increase farmers' profits.
66
How can farmers reduce the environmental impact of fertilizer use?
By not using too much fertilizer.
67
When should farmers avoid applying fertilizer?
Before rain is forecasted, to prevent leaching.
68
Where should fertilizers not be used?
Near streams or rivers, to avoid runoff into water bodies.
69
What is one benefit of using organic fertilizers like manure?
They do not contain nitrates that are easily leached from the soil.
70
How do organic fertilizers reduce the risk of eutrophication?
They release nitrates more gradually, lowering the chance of immediate pollution
71
Can organic fertilizers still contribute to pollution over time?
es, if overused, they can still cause long-term pollution.
72
What are plastics?
Plastics are human made materials, usually made from fossil fuels.
73
non-biodegradable
not able to be broken down by decomposers. Therefore they just accumulate.
74
What are the problems of non-biodegradable plastics?
* **Dangers to sealife**
Eg. Turtles eat plastic, accidentally thinking it is jellyfish (their prey).
It collects in their stomachs, unable to be broken down by enzymes, and they eventually die.
* **Dangers to land and aquatic life**
Animals get trapped in plastic – eg. bags wrap around their bodies, killing them.
Hermit crabs might choose plastic as a new home, instead of a shell – they could get trapped.
75
What does conservation do?
It protects biodiversity, as well as useful recources.
76
Sustainable resource
one that is produced as rapidly as it is removed from the environment (so it does not run out).
77
What methods can be used to use forests sustainably?
* Governments can refuse to grant licenses to companies who cut down forests
* selective-felling
* coppicing
* replanting new trees after cutting old ones
* education about importance of forests
* legal protection of parts of forests
78
What is coppicing?
cutting down trees to about 1m, from which they will grow back. This can be done over a cycle of many years, to different parts of the forest at a time.
79
Why is it hard for governments to refuse forest cutting grants liscenses?
governments can make a lot of money by granting those licenses.
80
What is selective felling?
instead of cutting all the trees down in an area, only cutting down a small portion of the trees at a time. The remaining trees maintain the soil, and habitat for other species
81
What is the con of using selective felling as a way to sustainibally use forests?
building access roads to do this
People working in the forest disturb the habitat
82
what is the problem with repkanting trees after cutting old ones as a way to sustainably manage forests?
Primary forest = forest that has never been cut down = highly valuable and supports biodiversity = should be conserved.
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