human impact on the environment

Question 2

species extinction

Answer 2

the death of the last individual
of a species capable of
reproduction.

Question 3

endangered species

Answer 3

one that is at risk of becoming extinct throughout all or a significant portion of its range.

Question 4

what human activities result in biodiversity crisis and why

Answer 4

Human activities such as deforestation, agriculture, over shing, pollution,
forestry, mining and urban expansion have all resulted in widespread habitat
destruction, resulting in a biodiversity crisis as species compete for resources.

Question 5

why have many species become endangered and extinct

Answer 5

Many species are becoming endangered and some have become extinct because of habitat destruction or through hunting and collecting, e.g. ivory.

Question 6

what is species extinction caused by

Answer 6

• Changes in climate which reduce vegetation and decreases atmospheric
  oxygen levels.
• Human activity, e.g. the dodo bird was indigenous to Madagascar and
  Mauritius, but habitat destruction and hunting by sailors resulted in the
  bird’s extinction by 1662.

Question 7

how are endangered species classified

Answer 7

Species are classi ed according
to their vulnerability to extinction: critically endangered, endangered, and
vulnerable.

Question 8

name three threatened species

Answer 8

• mountain gorillas
• giant pandas
• polar bears

Question 9

describe why species are at risk due to natural selection

Answer 9

• Requires mutations in the gene pool to confer a selectiveadvantage.
• Where species cannot adapt to changes in their habitats fast enough due to insufi cient mutations they can become threatened or extinct.

Question 10

describe why species are at risk due to habitat destruction

Answer 10

• E.g. deforestation and hedgerow removal. Hedgerows contain many different plant species supporting a wide variety of animal life,
• but their removal to allow for larger elds to accommodate agricultural
  machinery and the subsequent loss of wildlife corridors has reduced species
  numbers and affected food chains.

Question 11

describe why species are at risk due to pollution

Answer 11

• E.g. PCBs (polychlorinated biphenyls) were manufactured ascoolants and have since been banned due to their toxicity and carcinogenic nature.
• They are still found in the environment close to manufacturing sites.

Question 12

why are species at risk due to oil

Answer 12

• Oil is shipped worldwide to meet our energy needs, but accidents at sea
  have led to the discharge of millions of gallons of crude oil,
• e.g. Exxon Valdez ran aground off Alaska in March 1989 discharging oil into the
  estuary.
• In February 1996 the Sea Empress ran aground off the coast of Milford Haven in Pembrokeshire, spilling oil into the Cleddau Estuary endangering sea birds and marine life.

Question 13

why are species at risk due to overfishing and collecting

Answer 13

e.g. for food (bush meat), as exotic pets,
fashion, traditional medicine (tiger bone and rhino horn), and for souvenirs
and ornaments (turtle shell, ivory).

Question 14

why are species at risk

Answer 14

• natural selection
• habitat destruction
• pollution
• oil
• overhunting and collecting
• overfishing and agricultural exploitation
• competition from introduced species

Question 15

why does competition from introduced species cause species to be at risk

Answer 15

e.g. north American signal cray sh
was farmed in the UK but some escaped and now outcompete the
native cray fish.

Question 16

conservation

Answer 16

the protection, preservation management and restoration of natural habitats and their ecological communities to enhance biodiversity.

Question 17

what does conservation involve

Answer 17

Conservation involves the management of habitats to enhance biodiversity, and is important for a number of reasons:

Question 18

why is conservation important

Answer 18

• Ethical reasons: we have a responsibility to preserve the environment, not
  damage it.
• Possible medical uses: many drugs have been extracted from plants, e.g.
  quinine from Cinchona bark used to treat malaria, some chemotherapy
  drugs have a plant origin, and presumably many are yet to be discovered.
• Maintaining a healthy gene pool helps future-proof populations against
  environmental changes.
• Agriculture has selectively bred crops from wild varieties. In future, we
  may need to look at wild varieties to select suitable alleles to grow crops in
  harsher environments.

Question 19

seed and sperm banks

Answer 19

gene banks, protecting the genes from economically important or threatened
plants and animals.

Question 20

what are the four main conservation methods

Answer 20

• legislation
• captive breeding programmes
• education
• ecotourism

Question 21

what are the three types of legislation

Answer 21

• Annually, international wildlife trade is estimated to be worth billions of
  dollars. CITES (the Convention on International Trade in Endangered Species) agreement is enforced by strict customs controls, backed up by fines and
  even jail sentences, but it is difficult to enforce because not all countries have
  signed up, and it is very difficult to police or catch the smugglers involved.
  ■ The EU Habitats Directive prevents collection of some birds’ eggs, and
  reduces the picking of wild owers and over shing.
  ■ Establish protected areas, e.g. Sites of Special Scienti c Interest (SSSIs), and
  nature reserves, e.g. Gower coast.

Question 22

what are the four types of captive breeding programmea in zoos and botanic gardens

Answer 22

• Seed banks hold seeds from rare and traditional varieties in controlled
  environments, to protect against extinction of species.
  ■ Sperm banks store sperm from threatened species and are used in captive breeding to ensure genetic variety within populations.
  ■ Rare breed societies maintain older less commercial varieties.
  ■ Species reintroduction has been used successfully following captive
  breeding programmes to reintroduce species back into the wild, e.g. the red
  kite has been reintroduced back into mid-Wales.

Question 23

describe how education is a form of conservation

Answer 23

• Education through WWF (World-Wide Fund for Nature) and the Countryside Commission, which are responsible for raising awareness.
• The Countryside Commission is also responsible for establishing nature reserves.

Question 24

how is ecotourism a form of conservation

Answer 24

• Ecotourism, e.g. safaris, provides education and raises money to fund
  local conservation efforts by employing local people.
• This way, species have
  more value alive so there are clear incentives to conserve.

Question 25

ecotourism

Answer 25

responsible travel to natural areas that
conserves the environment and improves the well-being of local people.

Question 26

monoculture

Answer 26

the cultivation of a single species of crop

Question 27

what is agricultural exploitation and what are it’s problems

Answer 27

• This refers to the way in which food production has had to increase in
  efficiency and intensity to maximise crop yields in order to feed a growing
  population.
• Agricultural exploitation causes conflict between conservation and the need to mass produce food.
• Following World War II, larger elds
  were created by removing hedgerows to allow for larger machinery, which
  led to the loss of habitat for many organisms and reduced biodiversity.
• Farmers also employed monoculture by growing a single species of crop, e.g.
  wheat, to further increase yields, as all plants required the same nutrients,
  and harvesting was easier.

Question 28

what are the disadvantages of monoculture

Answer 28

■ It reduces biodiversity as there is only one habitat.
■ It provides an ideal environment for pests, so pesticides and herbicides have
to be used.
■ Farming reduces the ow of recycling of nutrients as when plants die and
decompose their constituent elements are returned to the soil, but farmers
often remove crop residue and therefore minerals from the soil.
* Farmers have to add inorganic fertilisers to their elds to increase nutrient content.
* This can cause eutrophication of waterways.

Question 29

what are farmers doing to prevent agricultural exploitation

Answer 29

Farmers are encouraged through the use of subsidies, where they are paid to manage their farms to increase biodiversity.

Question 30

what are the causes of deforestation

Answer 30

■ Use of land for agriculture for both subsistence farming and cash crops, e.g.
■ Palm oil
■ Soya bean
■ Biofuels
■ Cattle ranching
■ Timber extraction.

Question 31

what are the consequences of deforestation

Answer 31

• Habitat loss increases causing a reduction in biodiversity.
• Soil erosion increases as tree roots no longer bind soil, so rainfall on
  exposed slopes can remove top soil.
• Increase in sedimentation, as top soil is removed from upper slopes
  and deposited downstream by rivers, increasing the risk of ooding.
  Soil quality and structure deteriorates as there is no humus added to it
  from trees.
• Climate change due to reduced carbon dioxide uptake during
  photosynthesis.
• Less transpiration by trees reduces the amount of water vapour returning
  to the atmosphere, which reduces the amount of rainfall.
• Loss of plant species and potentially valuable plant chemicals that could be
  used to treat disease.
• Desertification.

Question 32

soil erosion

Answer 32

the removal of topsoil, which contains valuable nutrients.