5.2a Carbon Cycle

02/05/2013 § Leave a comment

It’s really all about recycling. While energy is transferred and moved around, it is lost sometimes. Nutrients, however, can be used again and again by being recycled. There are three stages that make up the pattern of nutrient cycles. First, autotrophs absorb inorganic matter and convert it into organic compounds, e.g. converting nitrate into amino acids. Secondly, consumers obtain that organic matter by eating the autotroph or eating other consumers. Finally, the dead organic matter is released by excrement or other waste material, or the animal simply dies. The organic matter left behind is then externally digested by saprotrophs and ingested by detritivores, nature’s two decomposers. This returns the nutrients back to their reserves for the next round.

Okay, so the greenhouse effect! We learned it last year but, come on, you can’t expect us to remember the things we learned a year ago. A greenhouse takes light and warms up solid surfaces, which then warm the air. This is why greenhouse gases are quite warm, similar to how cars get warm during the summer. This is how we can live on the earth, because the amount of carbon dioxide, methane, NOX and sulfur dioxide in the atmosphere keep the planet warm. Of course, the additional something-hundred-thousand ppm of CO2 (it’s probably more than that, though) that humans have been putting into the air has turned the greenhouse effect into global warming, which is the rising temperature on earth.

Essay Questions (got a long way to go)

  1. Outline what is meant by the trophic level of an organism with three examples from one named habitat. (4 max)
  2. Compare the ways in which autotrophic, heterotrophic and saprotrophic organisms obtain energy. (6 max)
  3. Draw a labelled sigmoid population growth curve. 4 marks
  4. Explain the factors that cause a population to follow the sigmoid ( S-shaped) growth curve. (8 max)
  5. Apply the concept of carrying capacity to the struggle for survival resulting from overproduction of offspring. (5 max)
  6. Outline the international system used for naming species of living organisms. (4 max)
  7. Discuss the definition of the term species. (8 max)
  8. Name the levels and the specific taxa in the hierachy of classification using humans as an example. (2 max)
  9. Describe the relationship between the rise in the concentration of atmospheric carbon dioxide and the enhanced greenhouse effect. 5 marks
  10. Outline the consequences of a global temperature rise on arctic ecosystems. 6 marks
  11. Outline the precautionary principle. 5 marks
  12. Outline the structural differences which characterize bryophytes, filicinophytes, coniferophytes and angiospermophytes. 9 marks
  13. List the structural differences between bryophytes and angiospermophytes. 5 marks
  14. Briefly explain Darwin`s theory of evolution. 4 marks
  15. Outline five types of evidence which support the theory of evolution by natural selection. 6 marks
  16. Outline one modern example of observed evolution by natural selection. 2 marks
  17. Explain the evidence from homologous anatomical structures that supports the theory of evolution. 6 marks
  18. Outline how antibiotic resistance in bacteria can arise in response to environmental change. 5 marks
  19. Antibiotic resistance in bacteria is an example of evolution in response to environmental change. Using another example, explain how an environmental change can lead to evolution. 8 marks



Page 185, nutrient cycles

1. Deduce what the “above ground” compartment consists of in an ecosystem. —> The above ground compartment in an ecosystem consists of trees, grass, animals, water.

2. State which biome has the largest “above ground” compartment. —> equatorial forest

3. Explain why it is difficult to grow crops in an area where equatorial forest has been cleared of its vegetation. —> The equatorial forest consists mostly of above ground areas where crops can grow. If the equatorial forest is cleared of its vegetation, then about 75% of the forest will have disappeared, and soil and root isn’t good enough nor is it sufficient to help crops grow.

4. State the name of the process carried out by decomposers and detritus feeders that releases CO2 into the atmosphere. —> recycling? Ingestion?

5. Suggest why most of the nitrogen in a tundra ecosystem is in the soil. —> Most of the nitrogen in a tundra would be in the soil because more than 80% of the tundra is made up of soil.

6. Explain why warming due to climate change might cause a release of CO2 from tundra soil. —> Climate change could cause a release of CO2 from the tundra soil because the heat causes it to leave the soil (?). The energy from the sun rays would hit the tundra and since the soil is abundant in nitrogen, the nitrogen reacts to the light, perhaps gets excited, and becomes too much for the tundra to hold only in the soil.

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