MICROORGANISMS : FRIENDS AND FOE (CHAPTER-2) 8th Class

These are definitions on chapter 2 (Microorganisms: Friends and Foe) of Class 8

DEFINATIONS:

·         ALGAE – A simple, non-flowering, and typically aquatic plant of a large assemblage that includes the seaweeds and many single-celled forms. ALGAE contain chlorophyll but lack true stems, roots, leaves, and vascular tissue.

·         ANTIBIOTICS- These medicines kill or stop the growth of the disease - causing microorganisms. Such medicines are called ANTIBIOTICS.

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        ANTIBODIES- When a disease- carrying microbe enters our body, the body produces ANTIBODIES to fight the invader.

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         BACTERIA- BACTERIA are prokaryotes, which consists of single cell with a simple internal structure.

·         CARRIER- The insects which transmits pathogens to human is called a CARRIER.

·         COMMUNICCABLE DISEASES- Microbial diseases that can spread from an infected person to a healthy person through air, water, food or physical contact are called COMMUNICABLE DISEASES.

·         FERMENTATION-This process of conversion of sugar into alcohol is known as FERMENTATION.

·         FUNGI- The group of organisms known as the fungi. This group includes the familiar organisms mushrooms, yeasts and molds.

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·         LACTOBACILLUS- LACTOBACILLUS is a bacterium which is present in curd. It promotes fermentation of curd from milk. It converts Lactose sugar into lactic acid to do the fermentation of curd.

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·         MICROORGANISMS- These are other living organisms around us which we normally cannot see. These are called MICROORGANISMS or MICROBES.

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·         NITROGEN FISCATION- The process of converting N2 gas of atmosphere into compounds of N2 is called N2 FISCATION.

·         NITROGEN CYCLE- The circulation of NITROGEN element through living things and non-living environment is called NITROGEN CYCLE.

·         NITROGEN FIXATION- Nitrogen fixation is a process by which nitrogen in the Earth's atmosphere is converted into ammonia (NH₃) or other molecules.

·         PASTEURISATION-  Pasteurised milk can be consumed without boiling as it is free from harmful microbes. The milk is heated to about 70 degree C for 15 to 30 seconds and then suddenly chilled and stored. By doing so ,its prevents the growth of microbes. It is called PASTEURISATION.

·         PATHOGEN-  Some of the microorganisms cause diseases in human beings, plants and animals. Such disease-causing micro-organism are called PATHOGENS.

·         PRESERVATION-  Salts and edible oils are the common chemicals generally used to check the growth of microorganisms. Therefore they are called PRESERVATIVES.

·         PROTOZOA- A phylum or grouping of phyla which comprises the single-celled microscopic animals, which include amoebas, flagellates, ciliates,  sporozoans, and many other forms.

·         RHIZOBIUM- A nitrogen-fixing bacterium that is common in the soil, especially in the root nodules of leguminous plants.

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·         VACCINE- An antigenic substance prepared from the causative agent of a disease or a synthetic substitute, used to provide immunity against one or several diseases.

·         VIRUS-An infective agent that typically consists of a nucleic acid molecule in a protein coat, is too small to be seen by light microscopy, and is able to multiply only within the living cells of a host.

YEAST-A microscopic fungus consisting of single oval cells that reproduce by budding, and capable of converting sugar into alcohol and carbon dioxide.