CBSE CLASS 12 -LAKSAY PROGRAMME

  • Organisms live around us which we cannot see with naked eye are called Microorganisms or microbes.
  • Microscope is required to see these microbes.
  • They live in all type of environments ranging from ice cold climate to hot springs, and deasert to marshy land.
  • They are also ground inside the bodies of animals and human beings.
  • Some microbes are helpful for human and animal while some are causing for disease .
  • The disease causing microbes are called pathogen.

Microorganisms called categorized into four groups:

  1. Bacteria : They are vey small,single called microorganisms. They don't have well defined nucleus and other sub cellular components. Ex. lactobecillus, Ribozium
  2. Fungi: They are large group of organism which don't have chlorophyll and do not perform photosynthesis. Ex. Yeast,mold,aspergilis,pencillium etc
  3. Protozoa : They are single called microorganism and classified as animals. Ex. Amoeba, paramicium, entaemoeba, plasmodoum etc.
  4. Algae : They are large group of plant like organism which have chlorophyll and perform photosynthesis. Ex: chlamydomonas, spirogyra, blue green algae etc

Viruses

  • Viruses are also microscopic but have different characteristics than microorganisms.
  • They reproduce only when inside the cell of host organism.Host organism may be a bacterium, plant or animal.

Is virus a microorganisms?

Viruses are microscopic parasites .It is much smaller than bacteria. Viruses behave like living organism when it is inside the host body otherwise Viruses behave like non living so the terms microorganisms doesn't included Viruses.

Diseases caused by :

  • Viruses- cold ,influenza (flu),cough, polio,chicken pox
  • Protozoa- Dysentery and malaria
  • Bacteria- typhoid, tuberculosis,diphtheria
  • Fungi- ringworm, athlete's foot
  • All microorganisms are not harmful ,some of them are brnificial.
Examples
  1. Ribozium bacteria helps for nitogen fixation in ligmanous plant and enrich the soil fertility.
  2. Lactobacillious bacteria permits formation of curd.It multiples and convert milk into curd.
  3. Bacteria are also involved in making cheese,pickle and many other food items.
  4. Yeast a kind of fungi are helpful in making bread.
  5. Microorganisms are used on large scale for commercial production of alcohols.
  6. Microoranisms are souce of many drug such as Antobiotic tablet,injections of penicillin .
  7. Some microorganisms decompose the organic waste and dead plant and animal into simple substance and help to clean the environment.

Vaccine

  • A mild form of disease that is injected into person or an animal's blood using a needle in order to protect the body against that disease.
  • When disease carrying microbes enters our body,the body produced antibodies to fight the invader.The body also remember how to fight against microbes if they enter again.
  • The antibodies remains in the body and we are protected against disease causing microbes.
  • Edverd Jenner invented the vaccine of small pox in 1798.
  • Diseases : Any things that disturbed ease is called disease.
Sources of pathogen entering in body
  1. Air
  2. Water
  3. Food
  4. Direct contact with infected person
There are two kind of disease.
  1. Communicable disease
  2. Non communicale disease

Communicable disease:

It spread from infected per to healthy person.
Examples: Chlora,common cold,chicken pox,tuberculosis

Non communicale disease

A non communicale disease is a disease that can not transmit from infected body to healthy body.
Ex. Diabetes, herpertention, heart disease etc
There are insects and animal which act as carrier of disease causing bacteria .

Examples
  1. House fly
  2. Anopheles mosquito carries parasite of materia called Plasmodoum
  3. Female aedes mosquito act as carrier of dengu virus.

Food preservation

Food preservation can be done by adding following chemicals in food.

  1. Salt
  2. editable oil
  3. Sodium benzoate
  4. Sodium metabisulphate
  5. Vinegar

Pasteurization

Pasteurization is a method to preserve milk, in which the milk is heated to about 700C for 15 to 30 seconds and then suddenly chilled and stored. By doing so, it prevents the growth of microbes. This process was discovered by Louis Pasteur. It is called pasteurization.

The person who started this techquie was Louis Pasteur.

Nitrogen Fixation

The process of converting nitrogen gas of the atmosphere or air into compounds of nitrogen(which can be used by the plants)is called nitrogen fixation. The nitrogen gas is the free nitrogen whereas nitrogen compounds are said to be fixed(converted into nitrogen compounds).