human influences on ecosystems

Question 1

why has food production increased

Answer 1

• improved machinery
• fertilizers
• insecticides
• herbicides
• artificial selection and genetic modification

Question 2

reasons for food shortages

Answer 2

Fast increase in population

Increasing use of crops for fuel

Decrease of farming = Climate change/Urbanization

Question 3

what is famine

Answer 3

Wide spread scarcity of food

Question 4

main causes of famine

Answer 4

The rapid rate of population increase

Long term climatic change

Soil erosion and desertification

Economic pressure

Unequal distribution of food

Drought

Flood

Question 5

what is monoculture

Answer 5

the continuous production of one type of crop that is often genetically uniform.

Question 6

negative impacts of monoculture

Answer 6

If a natural disaster were to occur, the whole crop could be wiped out.

If pests & disease attacked crop, it could harm it easily

Using large fields and pesticides reduces the variety of species. This hinders biodiversity.

Question 7

negative impacts of intensive livestock production

Answer 7

Welfare issues for the livestock

Diseases can spread easily among them

Waste can pollute land and waterways nearby

Question 8

reasons for habitat destruction

Answer 8

Increased area for food crop growth, livestock production and housing

Extraction of natural resources

Marine pollution

Through altering food webs, and food chains, humans can have a negative impact on habitats

Question 9

effects of deforestation

Answer 9

Reduced biodiversity/destroys habitats/extinction

Loss of CO2 fixation, thus increase in CO2, thus global warming

Soil erosion: tree roots cannot retain soil, goes into rivers making the water dirty & causes blockages, soil becomes less fertile

Flooding: usually 75% of water is absorbed by foliage, root systems or evaporates. After deforestation water, accumulates in valleys

Question 10

examples of water and air pollution

Answer 10

Chemical waste and sewage in rivers results in water not being drinkable and eutrophication can occur

Sulphur dioxide dissolves in rain, causing acid rain which increases acidity of lakes and leaches aluminium out of the soil

Question 11

effects of acid rain

Answer 11

The fishes’ gills are damaged, eventually killing them. This is fixed by adding calcium hydroxide (slaked lime)

Destroys top of trees and aluminium damages tree roots = dead tree, important nutrients leached away

SO2 poses health hazards for humans (asthma sufferers)

Damages limestone buildings and sculptures

Fewer crops can be grown on an acidic field (fixed by adding lime)

Question 12

pollution due to pesticides

Answer 12

Insecticides (kill insects): meant to kill insects which eat crops, but can kill other, useful insects such as bees which are pollinators, or by bioaccumulation (the increase in dose of toxin from one level of the food chain to the next)

Herbicides (kill weeds): can be harmful to animals which eat the plants

Question 13

effects of nuclear fall out

Answer 13

Radioactive particles are sprayed into the atmosphere in a nuclear accident or bombing;

These particle “rain” back to earth from clouds, sometimes far from the accident site;

The radioactivity damages DNA and causes cancer and radiation illness at every level of the food chain.

Question 14

effects of non-biodegradable plastics

Answer 14

Choke birds, fish and other animals

Fill up the animals’ stomachs so that they can’t eat food

Collect in rivers, and get in the way of fish

Question 15

acid rain causes and effects

Answer 15

Caused by sulphur dioxide (burning fossil fuels) and nitrogen oxides (nitrogen reacting hot engines), as they dissolve and cause acid rain

Damages trees and plants, and kills fish and other river life

Question 16

prevention of acid rain measures

Answer 16

Prevention: catalytic converters, in factories slaked lime neutralizes these acidic oxides and use of flue-gas desulfurization

Question 17

negative impact of female contraceptive hormones in water courses

Answer 17

Reduced sperm count in men and feminisation of aquatic organisms

Question 18

what is eutrophication

Answer 18

when water plants receive too many nutrients.

Question 19

process of eutrofication

Answer 19

Fertilisers put in soil by farmers

Fertilisers with nitrates / detergents with phosphates leach into rivers and lakes after rain

Water plants grow more than usual

They block sunlight and kill plants underneath

They die and sink to bottom

Bacteria/fungi decompose remains using the O2 and decreasing the O2 concentration

Fish and other creatures die from oxygen starvation

Question 20

what is a sustainable resource

Answer 20

one which is produced as rapidly as it is removed from the environment so that it does not run out

Question 21

what is sustainable development

Answer 21

development providing for the needs of an increasing human population without harming the environment

Question 22

what does sustainable development require

Answer 22

Management of conflicting demands

Planning and co-operation at local, national and international levels

Question 23

how can resources be maintained

Answer 23

Some resources can be maintained, limited to forests and fish stocks.

They can be sustained using:

Education

Legal quotas

Re-stocking

Question 24

water as a natural resource

Answer 24

used to grow food, keep clean, provide power, control fires and to drink. We get water constantly through rainfall but we are using up planet’s fresh water faster than it can be replenished.

Question 25

fossil fuels as a natural resource

Answer 25

need to be conserved as they will soon run out, they should be therefore replaced with green forms of energy.

Question 26

recycling of water

Answer 26

water from sewage can be returned to environment for human use by sanitation and sewage treatment

Question 27

recycling of paper

Answer 27

sent to special centres where it is pulped to make raw materials for industry

Question 28

recycling of plastic

Answer 28

fossil fuels, bottles
→
fleece clothing

Question 29

recycling of metal

Answer 29

mining takes a lot of energy so recycling saves energy

Question 30

why do species and habitats need to be conserved

Answer 30

Organisms have value in themselves (ethical value)

Value to medicine (new molecules from exotic plants = new drugs)

Genetic resources are useful to humans as well and are lost when species disappear (DNA for genetic engineering)

Each species has its role in its ecosystem; if it is removed, then the whole ecosystem could collapse

Question 31

how do species become endangered

Answer 31

climate change, habitat destruction, hunting, pollution and introduced species

If the population size drops, variation decreases

Question 32

how can endangered specied be conserved

Answer 32

monitoring and protecting species and habitats, education, captive breeding programmes and seed banks

Conservation programmes include:

reducing extinction

protecting vulnerable environments

maintaining ecosystem functions, by nutrient cycling and resource provision, e.g. food, drugs, fuel and genes