Micro organisms in the environment
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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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MICRO-ORGANISMS IN THE ENVIRONMENT

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Micro organisms in the environment

MICRO-ORGANISMS IN THE ENVIRONMENT

ABBOTTS COLLEGE


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


Micro organisms in the environment

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


Micro organisms in the environment

  • THE END


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