CBSE Class 8 Science Microorganism Friend And Foe Notes

CBSE Class 8 Science Microorganism Frind and Foe Chapter Notes. Learning the important concepts is very important for every student to get better marks in examinations. The concepts should be clear which will help in faster learning. The attached concepts made as per NCERT and CBSE pattern will help the student to understand the chapter and score better marks in the examinations.

MICROORGANISMS : FRIEND AND FOE

INTRODUCTION
r Microorganisms: The living organisms which cannot be seen by naked eyes and can be seen only through a microscope are called microorganisms or microbes.
• The branch of biology which deals with the study of microorganisms is known as microbiology.
• Father of Microbiology-Louis Pasteur
• The microorganisms include bacteria, fungi, viruses, algae and protozoans. Microorganisms may be unicellular like bacteria, some algae and some fungi and protozoa, or multicellular such as algae and fungi.

OCCURRENCE OF MICROBES
• Microorganisms can survive under all types of environment, ranging from ice cold climate to hot springs and deserts to marshy lands.
• They are also found inside the bodies of animals including humans.
• Some microorganisms grow on other organisms while other exist freely.
• Microbes can live alone, while fungi and bacteria may live in colonies.

MILESTONE IN MICROBIOLOGY
Antony van Leeuwenhoek (1632-1723) born in Holland, was the first person known to have viewed microbes with the help of self designed microscope. He discovered bacteria first, and then red blood cells, yeast in dough, sperm cells and many unicellular organisms. He drew a sketch of each tiny object he viewed and described its source, shape and structure to the best of his understanding.

class_8_science_concept_037

MICROSCOPES
There are two types of microscopes – a light microscope, which is commonly used in a school laboratory and an electron microscope. In a compound (light) microscope one of the two lenses used is as an "eye piece" and the other as an "objective". Eye is kept over the 'eye piece' and the object to be viewed is kept under the 'objective' on a transparent glass plate on the dias or the stage. This way the image of the object being viewed is magnified upto a thousand times.


class_8_science_concept_038

Electron microscope is a special type of microscope that uses beams of electrons instead of light, to provide magnification. Magnetic fields are used to bend the electron beams, just as rays of light are bent by the refractive power of a glass lens. Virus could be identified only through an electron microscope.

REVIEW QUESTIONS
1. What are microorganisms?
2. Define microbiology.
3. ______is known as father of microbiology.
4. Which type of microscope is commonly used in school laboratory?
5. Who is Antony van Leeuwenhoek?

GROUPS OF MICROORGANISMS
(A) Bacteria (B) Virus (C) Algae (D) Fungi (E) Protozoa

BACTERIA
• Bacteria were first observed in rainy water and later in teeth scum by Leeuwenhoek and he called them "animalcule".
• Cohn and Ehrenberg first of all coined the name "bacteria".
• Study of bacteria is known as bacteriology.
• They are basically unicellular but can exist as a chain or group of cells.
Occurrence : Bacteria are ubiquitous i.e., they occur anywhere and everywhere, in water in air, in soil and in all living organisms.
Size : Bacteria are very small organisms which are barely visible under the light microscope. Their sizes vary from 0.2 to 100 μ (micron) (1 micron = 10–6 meter).
1. Smallest bacterium = Haemophilus influenze
2. Largest bacterium = Epulospiscium fishelsoni
3. Longest filamentous bacterium = Beggiatoa mirabilis

class_8_science_concept_039

BACTERIAL CELL STRUCTURE
• Bacteria are unicellular microorganisms.
• They have a primitive cell structure.
• Each bacteria cell has rigid cell wall around it.
• There is no well-developed nucleus but chromatin or nuclear or genetic material or chromosome or DNA is found scattered in the jelly-like granular substance known as cytoplasm present inside the cell. This kind of nucleus is described as incipient nucleus or nucleoid.
 

Please click the link below to download pdf file for CBSE Class 8 Science Microorganism Frind and Foe Chapter Notes.

Tags: 

 


Click to View or Download pdf file
Click for more Science Study Material

Latest NCERT & CBSE News

Read the latest news and announcements from NCERT and CBSE below. Important updates relating to your studies which will help you to keep yourself updated with latest happenings in school level education. Keep yourself updated with all latest news and also read articles from teachers which will help you to improve your studies, increase motivation level and promote faster learning

Board Cancelled Official CBSE Statement

Keeping in view the requests received from various State Governments and the changed circumstances as on date, following has been decided- 1. Examinations for classes X and XII which were scheduled from 1st July to 15th, 2020 stand cancelled. 2. Assessment of the...

Board Exams helpline by CBSE

According to the recent announcement of CBSE, the pending Class 10 and 12 Board exams are going to be held from 01 July to 15 July 2020 in India. Along with this, it has also been decided to resume the free of cost tele-counseling service for students from 9.30 am to 5...

Board Exams Class 10 and 12 Notification by CBSE

Because of the prevailing condition of spread of COVID-19 pandemic in the country, special efforts are required for conducting examinations in a safe manner. As a number of students have shifted from the district of their school to some other district in the country,...

Procedure for correction in Name and Date of Birth

Procedure for correction in Name and Date of Birth in CBSE records Name Change: Applications regarding changes in name or surname of candidates will be considered provided the changes have been admitted by the Court of law and notified in the Government Gazette before...

Board Exams Class 10 and Class 12 Datesheet 2020

CBSE has announced the datesheet for the remaining exams of class 10 and class 12 exams. The exams are going to start in July. The class 10 and 12th board exams will be conducted for the remaining 29 papers from July 1 to July 15, 2020, at various centers nominated by...

×
Studies Today