Chapter 2 - Threats To Biodiversity

Question 1

How do humans directly exploit species for food?

Answer 1

• many species have been over exploited to provide food for humans, e.g, tuna, and cod
• some species have become extinct including the dodo, and great auk

Question 2

How do humans directly exploit species for fashion ?

Answer 2

• animal skins have been used for clothing throughout history. However, certain species have been over exploited for fashion, e.g:
  1) fur coats - leopard, tiger, snow leopard
  2) leather bags and shoes - crocodiles and alligators
  3) feathers from kingfishers, parrots, and ostriches

Question 3

How do humans directly exploit species for pets and entertainment ?

Answer 3

1) pets - parrots, snake, tropical fish
2) zoos - used to be common to collect wild animals for zoos
3) house plants - some tropical exotics and many insectivorous plants are collected in the wild to be sold

Question 4

How do humans directly exploit species for furniture and ornaments ?

Answer 4

1) lots of furniture is made with timber from tropical rainforest trees such as mahogany
2) black piano keys were made from tropical ebony wood and the white keys were made from elephant ivory
3) coral and sea shells have been collected and sold as tourist souvenirs

Question 5

How do humans directly exploit species for traditional medicines ?

Answer 5

1) tigers - different parts are used in the belief they cure a range of problems, for example claws as a sedative or the brain for laziness
2) rhinoceros - the horn is used as a supposed cure for many medical problems from nosebleeds to smallpox
3) seahorse - used to make medicines in the belief that they treat infertility, asthma and baldness

Question 6

What species have been deliberately eradicated from habitats?

Answer 6

1) animals which threaten humans e.g. sharks, or poisonous snakes
2) pathogen vectors e,g. Malaria mosquitos
3) predators of livestock e.g. wolves, lions, seals
4) wild herbivores that eat crops e.g, rabbits and deer
5) forestry pests e.g, wood boring beetles and beavers

Question 7

How do human activities effect the abiotic factor of water availability ?

Answer 7

• land drainage has affected large areas of wetlands as land has been reclaimed and farmland has expanded.
  -over exploitation of groundwater resources can lower the water table in the ground which may cause surface wetland habitats to dry out, making it impossible for wetland species to survive
• water level in tropical rivers may naturally rise and fall with the wet and dry seasons. Sand/river banks that are exposed during the dry season may be important nest sites for water birds

Question 8

How do human activities effect the abiotic factor of dissolved oxygen

Answer 8

• dissolved oxygen levels in water can be reduced by hot water discarded from power stations, or by discharging organic wastes, such as sewage, which deoxygenates the water as it decomposes
• ## reduction in oxygen levels can cause a reduction in the survival of speakers such as fish

Question 9

How do human factors effect the abiotic factor of temperature ?

Answer 9

1) hot effluent water
- an increase in water temperatures can increase the growth rates of aquatic vegetation, providing more food for aquatic animals, or it may increase the rate of decomposition causing deoxygenating

Question 10

How do human factors effect the abiotic factor of pH ?

Answer 10

• mine drainage water and pollutant gases from burning fossil fuels, or smelting metals, can produce acidic conditions
• these denature the cell proteins of exposed tissues. Some organisms or tissues are particularly vulnerable to acidic conditions e.g, fish eggs

Question 11

How do human factors effect the abiotic factor of water turbidity ?

Answer 11

-activities such as ploughing, mining, or dredging may increase water turbidity
- this can reduce light penetration and prevent submerged aquatic plants from photosynthesising.

Question 12

How do human factors effect the biotic factor of pollinators ?

Answer 12

-many plants rely on pollen being transported between their flowers by insects. If the insects were to die out, then the plants would not be able to reproduce.

Question 13

How do human factors effect the biotic factor of food chains ?

Answer 13

• the decline in populations of some species has been caused by the over exploitation of their food by humans, such as puffins which have declined as Sandeep’s have been over fished.

Question 14

How can introduced species cause a decline in population for a native species?

Answer 14

• the grey squirrel was introduced to the uk from North America. In many areas it has out competed f be indigenous red squirrel as it is better adapted to exploit the available food.
• rhododendrons we’re introduced to the UK from Asia because of their ornamental flowers. They are very invasive and shade the grind and prevent the regrowth of native vegetation.
• they also release toxins that inhibit the growth of other plants.

Question 15

How do human activists cause habitat destruction?

Answer 15

1) deforestation
2) ploughing of grassland
3) reservoir creation
4) urban expansion