AP 8th Class Biology Notes Chapter 2 Microorganisms Friend and Foe
→ Algae : A large group of simple non-flowering plants containing chlorophyll but lacking true stem, roots, leaves and vascular tissue.
→ Antibiotics : Substances that can kill bacteria are called antibiotics.
→ Antibodies : Substances that fight against disease causing organism.
→ Bacteria : Organisms not able to be seen except under microscope, found in rotting matter, in air, in soil and in living bodies.
→ Carrier : The animals and insects which carry the disease causing microbes and spread it from one person to another.
→ Communicable diseases : Microbial diseases that can spread from an infected person to a healthy person through air, water, food and physical contact.
→ Fermentation : Conversion of sugars into alcohol.
→ Fungi : Single cellular (or) multicellular organism without chlorophyll that reproduces by spores.
→ Fungi : Single cellular (or) multicellular organism without chlorophyll that reproduces by spores.
→ Lactobacillus : The bacteria that promotes the formation of curd.
→ Microorganism : The living organism that can’t be seen with our naked eye.
→ Nitrogen cycle : A cycle by which amount of nitrogen remains constant in the atmosphere is known as nitrogen cycle.
→ Nitrogen fixation : The process of conversion of atmospheric nitrogen into its usable forms is called nitrogen fixation.
→ Pasteurisation : The process in which milk is heated to about 70°c for 15 to 30 seconds and then suddenly cooled.
→ Pathogen : Disease causing microbes are termed as pathogens.
→ Preservation : Prevention of spoiling of food from the action of micro organisms is called food preservation.
→ Protozoa : A large group of single celled, eukaryotic organisms such as amoebas, ciliates, flagellates and sporozoans.
→ Rhizobium : A symbiotic nitrogen fixing bacteria present in the root nodules of legume plants.
→ Vaccine : Any antigenic preparation used to stimulate the production of antibodies and provide immunity against disease.
→ Virus : Viruses are living only inside the host cell. They are “connecting links between living and non-living”.
→ Yeast : A unicellular fungi, widely used in the process of fermentation.
→ The living organisms around us which are not visible to our naked eye are called as microorganisms.
→ These microbes can live in all kind of environment, ranging from ice cold climate to hot springs and desert to marshy lands.
→ They can be seen in air, water, soil and in bodies of plants and animals.
→ Microorganisms are mainly divided into bacteria, fungi, protozoa and some algae.
→ Viruses are quite different from other micro organisms. They reproduce only inside the host organism i.e., Bacterium, or plant or animal cell.
→ Viruses are considered as connecting link between living and non-living things.
→ Some microorganisms are very useful in our day to day life. They are useful in home, industry and cleaning the environment.
→ Some microbes are useful in the large scale production of medicines and alcohol.
→ Decormposers degrade the organic waste and dead plants and animals into simple substances and cleanup the environment.
→ Some microbes are harmful to us, they cause some serious diseases. They are called pathogens.
→ Protozoans cause diseases like malaria, dysentery.
→ Bacteria cause diseases like t.b. And typhoid.
→ Some microorganisms grow on food and spoil it. It leads to food poisoning.
→ The bacteria called ‘rhizobium’, present in the root nodules of legume plants fixes nitrogen in the soil.
→ Some bacteria present in the soil, fix nitrogen from the atmosphere and convert into nitrogenous compounds.
→ Certain bacteria convert nitrogenous compounds in the soil to nitrogen gas which is released to the atmosphere.
→ Conversion of sugars into alcohol by the help of yeast is called fermentation.
→ Antibiotics are produced from certain fungi like pencillium.
→ Food can be preserved for longer periods by adding salt, oil and sugar.