Microorganisms-Friends and Foe Notes

• Beside several kinds of plants and animals, there are other living organisms around us which could not be seen by naked eyes.
• These are called microorganisms or microbes.
• These microorganisms or microbes are so small in size that they cannot be seen with the unaided eye.

Micro organisms as observed under microscope

• Microorganisms are classified into four major groups.

Bacteria:

• They are the smallest and oldest living organisms existing on the earth.
• They are unicellular and prokaryotic organisms
• They have different type of shape like rod- shaped (bacilli), spherical (cocci) and spiral (spirilla).

Bacilli- E. coli:

Cocci- Streptococcus aureus:

Spirilli- Clostridium:

Fungi: