ocr f215 ecosystems exam questions

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Suggest environmental conditions that are requited

Climate

Food availability

Enough space/nesting sites

Ammount of predetation

Less interspecific compeition

Less disease

Low environmental resistance

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Explain what is meant by sucession

Natural changes in a species composition

Directional change 

Over a period of time

Reaching a climax community

One sere changes conditions for the next

Started by a pioneer species

Creation of niches

A number of recognisable stages

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Explain what is meant by biodiversity

Different species 

With different alleles

all living together in a habitat/ecosystem

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Outline Ecological, economical and ethical reasons

Ecological

  • Prevents disruption of food chains
  • Maintainance of ecosystem/habitat
  • Independence of species

Economic

  • Importance of large gene pool
  • Some species not yet discovered can be used for medicines
  • Fishing/agricultural purposes
  • Tuourism

Ethical

  • Reduction oin biodiversity due to human activity
  • Moral responsibility to put things right
  • Fix it for future generations
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List why tropical rainforests were destroyed

Wood cut for export/sold

Agricultural reasons eg growing crops/farming

Cleared for towns

Building roads

Space for housess

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Describe the important features of a tropical rain

  • High biodiversity
  • Deforestation reduces biodiversity
  • Decrease in gene pool
  • Acts as a carbon sink
  • Remove CO2 from atmosphere
  • Release CO2 when burnt
  • Less photosynthesis, less O2 produced
  • Transpiration contributes to atmospheric water content
  • Destroys water cycle
  • Rainforests supply crops eg nuts, rubber, fruit
  • Some drugs found only in rainforests
  • Soils become nutrient deficient, cant sustain agriculture without trees
  • Increased risk of soil erosion
  • Moral responsibility
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Explain why biologyical pest control is preferred

Insecticides harmful to other organimsms/ may kill natural predator to pest

Reduces species diversity

Many insecticides long lasting

Bio-accumulate along food chain

Damage to top carnivores, accumulation of herbicide

eg shell thinning

Poisonous to people applying them

Pests can build up resistanc (natural selection)

Run off contaminates water supplies

Residues in food

Pesticides must be repeated

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