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MICRO-ORGANISMS IN THE ENVIRONMENT

MICRO-ORGANISMS IN THE ENVIRONMENT. ABBOTTS COLLEGE. MAINTAING A BALANCE IN THE ENVIRONMENT. PAGE 9. Most micro-organisms are harmless or extremely useful Play a role in keeping eco-systems stable They give the environment a better chance to survive changes or threats

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MICRO-ORGANISMS IN THE ENVIRONMENT

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  1. MICRO-ORGANISMS IN THE ENVIRONMENT ABBOTTS COLLEGE

  2. MAINTAING A BALANCE IN THE ENVIRONMENT PAGE 9 • Most micro-organisms are harmless or extremely useful • Play a role in keeping eco-systems stable • They give the environment a better chance to survive changes or threats • The web of life heavily depends on these organisms with their huge biodiversity • Ensure environmental stability • Responsible for a wide range of vital functions in the environment Chapter 4

  3. FUNCTIONS OF MICRO-ORGANISMS IN THE ENVIRONMENT • Plant-degraders • Micro-regulators of nutrients • Regeneration of oxygen • Nitrogen transformers • Biological control agents PAGE 10

  4. PLANT-DEGRADERS • Cellulose degrading fungi or bacteria clean up dead plants in the environment

  5. MICRO-REGULATORS OF NUTRIENTS • Nutrients like carbon, nitrogen, phosphorus and sulphur are recycled in the environment • Saprotrophic bacteria and fungi are called microregulators because they break down the remaining organic matter from dead organisms into carbon dioxide and nutrients • Protozoan protists are micro-regulators in marine ecosystems • The nutrients eg nitrates and phosphates are absorbed by land plants and algae for growth

  6. REGENERATION OF OXYGEN • Micro-organisms play a vital role in keeping the level of oxygen at 21% in the atmosphere • Cyanobacteria (bacteria which can photosynthesise) and phytoplankton are vital oxygen generators • They replace about 50% of all used oxygen

  7. NITROGEN TRANSFORMERS PAGE 11 • Nitrifying bacteria change nitrogen into a useable form ie nitrates

  8. BIOLOGICAL CONTROL AGENTS • Micro-organisms can act as natural enemies of pests, pathogens and weeds eg fungus which destroys Port Jackson willow • This keeps the environment healthy and balanced

  9. TO DO • TEXTBOOK PAGE 10 LEARNING ACTIVITY 7: KEEPING ENVIRONMENT BALANCED

  10. ROLE OF MICRO-ORGANISMS IN SYMBIOTIC RELATIONSHIPS PAGE 11 • Symbiosis is a close relationship between different species • There are three types of symbiosis • Mutualism (both species benefit) • Parasitism (one benefits and the other is harmed) • Commensalism (one benefits the other is not harmed) • Examples of symbiosis • E coli and humans • Nitrogen fixing bacteria and plants • Mycorrhizal fungi and plant roots

  11. Escherichia coli and humans • An example of mutualism • Harmless strains of Escherichia coli (E. coli), a bacterium, are found in the colon as part of of the normal gut flora • Human flora are micro-oganisms (bacteria and fungi) that inhabit the human body • Some are useful for the human host • The majority have no beneficial or harmful effect Chapter 4

  12. Figure 1: Location of normal microbial flora bacterial cells in the human flora

  13. Escherichia coli and humans • In this mutualistic relationship: • Bacteria benefit by obtaining glucose and other nutrients from the undigested food remains in the colon • Humans benefit by gaining Vitamin K needed in the process of blood clotting • And protection against the growth of pathogenic bacteria within the gut

  14. Nitrogen-fixing bacteria and plants PAGE 11 • Nitrogen fixation is necessary to convert atmospheric nitrogen into forms that living organisms can use • Lightning can also cause nitrogen fixation • But most is done by symbiotic bacteria like Rhizobium • Rhizobiumlives in root nodules of legumes (peas and beans) Nodules formed where Rhizobium bacteria infected soybean roots Rhizobiumleguminosarum nitrogen fixing bacteria. Chapter 4

  15. Nitrogen-fixing bacteria and plants • Rhizobium benefits by gaining glucose and other nutrients, as well as a favourable habitat, from the plant • The plant benefits by gaining ammonia, produced by the bacterium from gaseous nitrogen and hydrogen • The plant uses the ammonia to make amino acids, which form proteins • As a result nitrogen from the atmosphere is fixed into organic material which results in plant growth Rhizobiumleguminosarum

  16. MYCORRHIZAL FUNGI AND PLANT ROOTS PAGE 12 70 – 80% of all plants have mycorrhizae The fungi send out hyphae to increase surface area of the plant roots • Fungus gets glucose from the plant • Plant gets: • an increased surface area for water and nutrient absorption • Protection against pests and disease

  17. TO DO • TEXTBOOK PAGE 12 LEARNING ACTIVITY 8: MUTUALISM

  18. THE END

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