The diagram shows the factors & the ‘players’ that affect the condition of an ecosystem <ul><li>A) Explain how either fact...
What did the examiners say? <ul><li>Whilst this question was by far the most popular, it yielded a frequently mediocre per...
<ul><li>3(a) In general 3(a) was done much more successfully than 3(b) with some good knowledge of both factors and player...
<ul><li>In 3(b) many candidates performed less effectively for a number of reasons. Firstly answers were overlong for 3(a)...
<ul><li>Many factors affect the condition of marine coral reef ecosystems. Corals are made of fragile polyps which live in...
Next? <ul><li>Write an answer for section 3 b) based upon tropical or boreal forests. Use the model answer to decide what ...
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Qu 3 2006 Paper 4

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Question, examiners comment & model answer -conservation of global biomes

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Qu 3 2006 Paper 4

  1. 2. The diagram shows the factors & the ‘players’ that affect the condition of an ecosystem <ul><li>A) Explain how either factors or players shown can affect the condition of named ecosystems (12) </li></ul><ul><li>B) With reference to one named global ecosystem, assess its value as a provider or goods & services </li></ul>
  2. 3. What did the examiners say? <ul><li>Whilst this question was by far the most popular, it yielded a frequently mediocre performance especially for forests. Marine ecosystems, especially coral reefs provided some outstanding responses. </li></ul>
  3. 4. <ul><li>3(a) In general 3(a) was done much more successfully than 3(b) with some good knowledge of both factors and players (some candidates unfortunately did both, or a hybrid answer) well linked to ecosystem conditions. Successful answers (see below) supported their statements with examples, brief case studies, and precise data, for example on the impact of climate change and natural catastrophe on coral reefs. In this section examples could be taken from across the range of ecosystems, but it was important that both positive and negative impacts were considered. </li></ul>
  4. 5. <ul><li>In 3(b) many candidates performed less effectively for a number of reasons. Firstly answers were overlong for 3(a) and there were many instances of truncated 3(b) answers. Secondly the question required a global ecosystem and this is not Korup,or Souffrière reef in St Lucia. Thirdly candidates were very confused about the value of goods and services with some very weak statements such as that rain forests don’t actually provide any/or many services!... Don’t you dare!!!!!!!! </li></ul>
  5. 6. <ul><li>Many factors affect the condition of marine coral reef ecosystems. Corals are made of fragile polyps which live in symbiosis with algae and are therefore very susceptible to damage. Natural conditions affect coral reefs as corals need very specific conditions for survival – warm water >20°C and shallow, clear, nutrient free water <30m deep. Global warming affects corals in three ways: increased temperatures cause coral to expel their zoozanthellae, causing bleaching and death eustatic sea level rise drowns corals and mangrove forests which offer protection to corals increased carbon dioxide concentration. El Niño Southern Oscillation can have similar effects with the periodic increase in sea temperatures in some areas. Corals are also susceptible to hurricane damage where large waves and high winds physically ‘batter’ corals and cause damage. Social and economic conditions can affect coral condition – large populations require more coastal resources which may result in overfishing of coral reefs, damaging food chains. A larger population will also create more waste ie effluent and sewage which makes the sea water murky, making it difficult for coral algae to photosynthesis. Sewage can also lead to eutrophication. The amount of pollution also depends on economic activities and Science and Technology. Coastal industry may release large amounts of effluent. This is a particular problem along the reef on the east coast of Tanzania where an increase in industry but no pollution control due to lack of technology has resulted in pollution of the reef, particularly around Marsia Island. Coastal developments, such as hotels in the enclaves of the Caribbean, also worsen the pollution problem twofold. Mangrove forests are cleared to allow for coastal developments. Mangroves naturally intercept pollutants and sediments which will make clear water murky. Runoff from roads is greater after mangrove deforestation, damaging coral ecosystems. The hotels also add pollutants and sewage causing major deterioration, especially after tropical storms lead to flash floods on deforested hillsides such as Tropical Storm Debbie in St Lucia. Resource extraction from corals is coral mining, for construction and the tourist souvenir/aquarium trade. This activity is damaging the coral reefs and is a particular problem in Sri Lanka. Hydrocarbon extraction from corals is also a problem as they are used as an alternative fuel source. Political stability influences coral condition as do illegal activities such as cyanide fishing and dynamite fishing damage the food chain and coral structure, a major problem in Dar-es-Salaam, Tanzania. Alternatively stable political situations can lead to the development of conservation programmes and investment in education (SNMA St Lucia). Tourism is a major cause of coral damage. Anchor damage, litter, diving, selective fishing and boat pollution worsen water quality and damage corals, a particular problem in dive hot spots such as Molokai in Hawaii. Where human activity has damaged corals they are more susceptible to predation by Crown of Thorn Starfish. It is believed that Crown of Thorn Starfish prosper in polluted water as they feed on corals – a major problem in the barrier reef. </li></ul>
  6. 7. Next? <ul><li>Write an answer for section 3 b) based upon tropical or boreal forests. Use the model answer to decide what to include & how much detail to write in. </li></ul>

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