State true or false. If false, correct the statement.

Citrus canker is transmitted by insects.

1. Introduction to Microorganisms:

(i) Microorganism is the organism which is too small that they cannot be seen through the naked eye. They can be seen with the help of a microscope.

(ii) Microbiology is the science that deals with the study of microorganisms.

(iii) Microorganisms can be studied under five categories. They are Virus, Bacteria, Fungi, Algae, and Protozoa.

2. Virus:

Virus shows both living and non-living characteristics. It contains genetic material (DNA or RNA) and protein.

3. Bacteria:

(i) Bacteria is a prokaryotic, single-celled organism. 

(ii) According to the shape of their cells, bacteria are of four major types: Bacillus (Bacillus anthracis), Spirilla (Helicobacter pylori), Cocci (Streptococcus pneumoniae), and Vibrio (Vibrio cholera).

(iii) According to the number and arrangement of flagella, bacteria are classified into five major types. They are Monotrichous, Lophotrichous, Amphitrichous, Peritrichous and Atrichous.

4. Fungi:

Fungi is a eukaryotic, non-photosynthetic, spore-forming organism. They range from single-celled organisms (e.g. Yeast) to very complex multicellular organisms (e.g. Mushroom). 

5. Algae:

Algae is a single-celled or multicellular eukaryotic, photosynthetic organism. Examples: Chlamydomonas and Spirogyra.

6. Protozoa:

(i) Protozoa is a eukaryotic, single-celled organism that usually lacks chlorophyll. Examples: Amoeba, Paramecium, Euglena and Plasmodium.

(ii) Euglena is a special organism that possesses characteristics of both plant and animal microorganisms.

7. Uses of Microorganisms in Medicine:

(i) We obtain antibiotics and vaccines from microbes.

(ii) Antibiotics is a substance produced by living organisms that inhibits or kills microorganisms such as bacteria. 

(iii) Alexander Fleming was the first person to discover the antibiotic Penicillin in the year 1928.

(iv) A vaccine is a biological preparation that provides immunity to a disease.

(v) Edward Jenner was the first person to discover a smallpox vaccine.

8. Uses of Microorganisms in Agriculture:

In agriculture, microorganisms are used as a natural fertilizer, nitrogen fixation, biocontrol agents, etc.

9. Uses of Microorganisms in Industry:

In industry, microorganisms are used in sewage treatment, production of biogas, production of alcohol and wine, retting and tanning process.

10. Uses of Microorganisms in Daily life:

In daily life, microorganisms are used in the preparation of curd, cottage cheese, bread, etc. 

11. Harmful Microorganisms:

(i) In the human intestine, microorganisms help in digestion of food and fight against harmful disease-causing organisms.

(ii) Tuberculosis, cholera, common cold, malaria, amoebic dysentery, rabies, anthrax, foot and mouth disease, etc., are a few examples of diseases caused by microorganisms in animals.

(iii) Citrus canker and potato blight disease are a few examples of diseases caused by microorganisms in plants.

12. Microbes in Food Process:

Preservation of food can be done by drying, heating, salting or by adding sugar, chemicals or by freezing and pasteurization.

13. Prions:

A prion is a mutated form of a usually harmless protein.

14. Virions:

A virion is an entire virus particle consisting of an outer protein shell called a capsid and an inner core of nucleic acid (RNA or DNA).