Human Impact on the Environment (DONE)

Question 1

What is extinction?

Answer 1

The complete loss of a species

Question 2

How may a species become extinct or endangered?
(6 marks)

Answer 2

• Natural selection
• Loss of habitat due to deforestation
• Overhunting/Overfishing by humans
• Competition
• Pollution
• Population too small/ lack of genetic biodiversity to ensure a healthy and viable increase in number

Question 3

Why is extinction a concern?

Answer 3

• Reduction in gene pool
• Losing potential useful genes (such as disease resistance)
• Source of food
• Potential medicines from plants

Question 4

What is deforestation?

Answer 4

The complete loss of trees due to human activity in a defined area.

Question 5

What are the consequences of deforestation?
(6 marks)

Answer 5

• Soil erosion
• Lowland flooding
• Desertification (drought)
• Habitat loss
• Decrease in biodiversity
• Climate change due to increase atmospheric CO2

Question 6

What is slash and burn (deforestation technique)?
(4 marks)

Answer 6

• Used to produce more fertile soil
• Land is exposed to wind/heat/water
• Leaching of nutrients
• Harsh environments to recolonise

Question 7

What is logging (deforestation technique)?
(3 marks)

Answer 7

• Timber for building/clearing areas for building
• Results in increased usage of machinery
• Loss of habitats

Question 8

Describe coppicing (forest management)

Answer 8

• Tree trunks are cut at their base, leaving a stool
• New shoots grow from the stool, which can be harvested at different diameters

Question 9

What are the benefits of coppicing?
(6 marks)

Answer 9

• Increases biodiversity
• Provides a variety of habitats
• New stems grow more rapidly than saplings
• Lifespan of tree extended
• Large machinery not used
• Forest floor receives more light

Question 10

What is sector felling?
(4 marks)

Answer 10

• Long rotation time
• Leaving forest areas for years before harvesting due to time for species to grow
• Don’t harvest adjacent sectors to prevent constant migration
• Never cut central area

Question 11

What is selective cutting?
(3 marks)

Answer 11

• Trees of high significance/value are cut down
• Leaves a gap in forest to allow light to penetrate
• Young trees/other plant species grow quickly and fill gap

Question 12

Describe good treefarming practices.
(5 marks)

Answer 12

• Plant trees optimal distances apart to reduce competition
• Replanting/protected areas to conserve species
• Control of pest/disease to increase yield
• Controlled timber cutting
• Protection of native woodland

Question 13

What is monoculture?

Answer 13

When genetically identical crops are grown on a massive scale in a defined area.

Question 14

What are the problems associated with monocultures?
(4 marks)

Answer 14

• Provide only one type of habitat, which reduces
  biodiversity
• Reduce soil fertility as roots grow to the same length and extract minerals from the same depth
• Increases the need for chemical fertilisers
• Overuse of pesticides to control the spread of pests and diseases

Question 15

What are the problems associated with overgrazing?
(4 marks)

Answer 15

• Causes soil compaction
• Reduces air spaces
• Inhibits nitrogen fixing and nitrifying bacteria leading to loss of soil fertility
• Water unable to penetrate compacted soil and grass growth is inhibited

Question 16

What is overfishing?

Answer 16

The rate at which fish harvesting exceeds the rate of reproduction

Question 17

What are the issues associated with overfishing?
(3 marks)

Answer 17

• Depletion of fish stocks
• Fish populations too low to recover (no longer viable)
• Impacts food chain and ecosystem (loss in biodiversity)

Question 18

Describe the method of drift netting that commercial fishing employs use.

Answer 18

A net, suspended from floats is stretched between two boats. Thousands of miles of nets are set and non-target species are often caught.

Question 19

Describe the method of trawling that commercial fishing employs use.

Answer 19

Weighted (with heavy iron beams) nets are dragged across the ocean floor. This methods catched everything and damages the ocean floor, decimating habitats for many miles.

Question 20

Describe methods that are used to preserve fish stocks/ reduce overfishing.
(6 marks)

Answer 20

• Exclusion zones enables fish populations to recover
• Fishing quotas give total allowable catches set for each species
• Regulation of mesh sizes allow smaller fish to escape and avoids young fish being caught to enable them to grow to breeding size.
• Fishing seasons
• Reduction in fishing fleets/number of days spent at sea
• Landing size regulation so undersized fish cannot be landed for sale

Question 21

What is conservation?

Answer 21

The planned preservation, protection, management and restoration of natural habitats and their ecological communities (biodiversity).

Question 22

How can conservation be achieved?
(7 marks)

Answer 22

• Sperm/seed banks
• Protecting habitats (e.g. SSSIs and Nature Reserves)
• Rare breed societies (breeding programs)
• Restricting trades internationally(CITES)
• Legislation
• Species reintroduction
• Ecotourism which aims to educate, conserve and contribute to local economies

Question 23

What is fish farming?

Answer 23

Large-scale, intensive farming where fish are bred and matured in enclosed ponds.

Question 24

What are the problems associated with fish farming?
(7 marks)

Answer 24

• Rapid spread of disease and parasites due to high density of farmed population
• Overuse of antibiotics and pesticides which can enter food chain
• Bioaccumulation causing reduced fertility at higher trophic levels
• Eutrophication caused from nitrogenous waste pollution
• Feed made from other fish = waste of resources
• Escape of farmed fish can carry disease and outcompete native species for resources
• Alter genetic characteristics of wild fish should farmed fish escape

Question 25

What is an environmental impact assessment?

Answer 25

A process for identifying the positive and negative environmental effects of proposed developments.

Question 26

What should an environmental impact assessment include?
(3 marks)

Answer 26

• Description of the site and proposed project
• Description of the abiotic and biotic factors
• Mitigations - ways of limiting the environmental damage and maintaining biodiversity

Question 27

What are planetary boundaries?

Answer 27

They define the safe operating space for humanity. Once exceeded all boundaries, Earth may no longer be able to support a human population.

Question 28

What are the 9 planetary boundaries and have they been crossed/avoidable/not quantified/avoided?

Answer 28

• Biodiversity/Biosphere integrity YES
• Climate change YES
• Nitrogen/Biogeochemical flow YES
• Land use YES
• Fresh water use AVOIDABLE
• Ocean acidification AVOIDABLE
• Ozone depletion AVOIDED
• Atmospheric aerosols NOT QUANTIFIED
• Introduction of novel entities/chemical pollution NOT QUANTIFIED

Question 29

Explain each planetary boundary.

Answer 29

• Biodiversity > Habitat destruction/ extinction rate increased. Loss of useful genes
• Climate change > Disruption to the carbon cycle. Release of CO2 on massive scale
• Nitrogen > Disruption of nitrogen cycle. Water logged or compacted soils. Eutrophication
• Land use > More landed used for large population. Monocultures
• Fresh water use - Climate change and chemical pollution. Desalination
• Chemical pollution > SO2 and NO2. Radioactive materials and plastics. New technologies and materials
• Aerosol > Air pollution by microscopic particles by combustion of fossil fuels. Respiratory problems, reduced photosynthesis. Reflection of sunlight from SO4 and absorption of sunlight from soot
• Ocean acidification > Increasing due to atmospheric carbon dioxide conc also increasing. CO2 dissolves in water. Damages fish gills.
• Ozone boundary > CFCs banned as they cause ozone depleting free radicals.