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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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maintaing a balance in the environment
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

functions of micro organisms in the environment
FUNCTIONS OF MICRO-ORGANISMS IN THE ENVIRONMENT
  • Plant-degraders
  • Micro-regulators of nutrients
  • Regeneration of oxygen
  • Nitrogen transformers
  • Biological control agents

PAGE 10

plant degraders
PLANT-DEGRADERS
  • Cellulose degrading fungi or bacteria clean up dead plants in the environment
micro regulators of nutrients
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
regeneration of oxygen
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
nitrogen transformers
NITROGEN TRANSFORMERS

PAGE 11

  • Nitrifying bacteria change nitrogen into a useable form ie nitrates
biological control agents
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
to do
TO DO
  • TEXTBOOK PAGE 10

LEARNING ACTIVITY 7: KEEPING ENVIRONMENT BALANCED

role of micro organisms in symbiotic relationships
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
escherichia coli and humans
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

slide12

Figure 1: Location of normal microbial flora

bacterial cells in the human flora

escherichia coli and humans1
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
nitrogen fixing bacteria and plants
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

nitrogen fixing bacteria and plants1
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

mycorrhizal fungi and plant roots
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
to do1
TO DO
  • TEXTBOOK PAGE 12

LEARNING ACTIVITY 8: MUTUALISM

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