microorganisms now let's first understand the term microorganisms

microorganisms now let's first understand the term microorganisms
microorganisms now let's first understand the term microorganisms

Welcome we'll start with class eight science the second chapter where we will talk about microorganisms now let's first understand the term microorganisms so let's say when we talk about organisms all of us are included in the category of organism the word micro as soon as it comes that means small ah very small I would say rather which cannot be seen by unaided eyes so I need some kind of aid to help see those objects.

 So what could be those aids those could be lets say a magnifying glass so if it's a kind of little bigger object I can use a magnifying glass to view it in cases where the microorganism is really really small what we use is a microscope so this is an example of microscope you have a mirror here you place your object here that you want to see on a slide and with this which is known as the lens you have different powers of the lens you can see zoom out and see from here what actually the organism looks like.

 So this is what we understand by microorganisms or we also call them as microbes now these microbes can be classified into four categories those are algae fungi bacteria and protozoa besides these four there is another criteria that we consider and that is virus the basic difference between these and viruses virus can survive and multiply only on a living host so it requires let's say a plant and organism on which it can survive and multiply so we have different examples for algae now for like.

 LG is multicellular in nature material can be unicellular now bacteria on the common bacterias you might be familiar with other diseases that are caused by bacteria which are tuberculosis and typhoid one of the major diseases in the then you have fungi now when we talk about fungus let's say you have a bread mold if you keep it for a few days you would see a kind of green growth on the bread piece and that is what is fungus so fungus is again multicellular in nature then you have protozoa a common diseases caused by protozoa malaria and dysentery we'll be discussing these and details now in the next as we said as virus virus requires some kind of living organism or living host on which it could survive now it can be bacteria it could be plant it could be animal or any other organism on which it can survive some of the common ailments which are caused by virus is cold influenza common cold flu so all these are caused by virus again.

 Among the major diseases you have polio which is considered to be eradicated now through the pulse polio program that was released now polio drops occur or polio vaccination polio basically now has vaccination we'll talk more about vaccination in Hawaii so this polio vaccine could be oral or as given as drops or injectable we'll talk about that as well and then you have chickenpox so these are some of the diseases that could be caused by virus the next what we already talked about is the multicellular and unicellular.

 So as we understand if I just mark a single cell we say it's a unicellular if I say there are number of cells which are present here we say it's multicellular so good example of multicellular r.l guy and fungi however unicellular includes some many guy you have protozoa bacteria which are predominantly considered as unicellular all these microorganisms that we have talked about have specific conditions to survive some can live in cold climates some can survive good in warm climate similarly some can some need to depend on other organisms some can survive independently so all these characteristics vary from.

 Organisms to or get microorganisms to microorganisms now microorganisms themselves could be categorized into two categories one are the friendly microorganisms and other are the harmful microorganisms as soon as we name microorganism what it strikes to our mind as diseases so we are all thinking about n number of different diseases so all those are definitely the harmful microorganisms that are present but on the other hand we do have good microorganisms that are present in the body.

 So these microorganisms help or accentuate the process so let's say you have curd now curd or yogurt what we see has a bacteria which is known as lactobacillus now this led to bacillus basically multiplies and as it multiplies if you have seen anytime with the milk you can with a milk and a small amount of curd in it you can have a whole bowl of curd that could be prepared and that's how the multiplication of lactobacillus takes place so bacterias used in lactobacillus bread cake all those are considered as.

 Good bacterias or friendly bacterias similarly in the soil you have the roots of the plant and within the roots you have the nerd use that are present so the leguminous plants which have root nodules have the bacteria which is known as rice opium and this Rhizobium bacteria helps in nitrogen fixation so this nitrogen fixation is again important because in atmosphere we have the nitrogen that is present in the gaseous form or the raw form that's nitrogen we need to convert it into a nitrogenous compound that could be used by the plants and furthered by the animals so let's say you have nitrogen this nitrogen is converted into nitrate nitrite into nitrate and this process of conversion goes through the process of nitrogen.

 Fixing which we will understand in a while in the nitrogen fixation now this was one of the examples where we talked about the friendly bacterias the next is let's say if you're fond of eating South Indian dishes like idli dosa what happens is you require a batter for it and this batter needs to be fermented so this fermentation helps or takes place with the help of yeast and bacteria and therefore we can say yeast or certain bacterias that help in the fermentation are also friendly bacterias so yeast has a capacity to reproduce or multiply at a faster pace and during this process since it's a process of fermentation carbon.

 Dioxide is released and this release of carbon dioxide basically accentuate the process of fermentation and the batter formation similarly if we talk about production of wine you have fermentation that takes place so wine production can go through or can be done by let's say grapes or any other acetic acid or alcohol formation so all these requires basically the process of fermentation so sometimes there are.

 Fermentations that could be done in the home by using yeast as one of the major sources sometimes they require a large-scale production so these large-scale commercial wineries would go for commercial production of yeast similarly you have the breaking down or conversion of sugar into alcohol and this process is again taking place by the process of yeast or by the use of east and finally you have the fermentation and formation of alcohol now as we said you have bacterial growth or microorganisms.

 Growth now microorganisms as we said could be classified and a different hand hits one of this is bacterium to cut the growth of these bacteria you need something that can destroy these bacterias and those are antibacterial these antibacterial drugs could be in the name of antibiotics or in the Gendry of antibiotics so these antibiotics base really stop the growth of microorganisms good examples of entropy antibiotics include streptomycin tetracycline rocks a cyclin so all those are basically antibiotics the first antibiotic was discovered by Alexander Fleming the name of the antibiotic was penicillin and this is sometimes a.

 Kind of direct question that is asked for your examinations nowadays we have lots of news of developing antibiotic resistance and avoiding the use of antibiotics and livestock's because it affects the growth of the livestock so antibiotics are in controversies these days what we can see now unnecessary use of antibiotics again can be harmful for the body and antibiotics as we said protect us from bacterial growth so antibiotics do not have any action in case of virus attacks so for virus you need any viral drugs not antibiotics.

 So let's see if you are suffering from influenza a common cold which is viral borne the role of antibiotics would not be would not be feasible or antibiotics won't prove or give fruitful results the next test vaccines now what happens in the vaccines so you have antibodies that are developed in the body and these antibodies basically protect us from the various diseases so once you have the disease that invents the body you have intimate antibodies that develop and these antibodies basically try to protect us from those diseases and this process is known as vaccination the first or the initial vaccination was developed for smallpox by.

 Edward Jenner and now smallpox has been eradicated worldwide how the eradication of smallpox has been done is through ring vaccination so what basically happens is you have a person who is exposed you have the primary ring where you have the exposure and then you have the secondary exposure areas so all those regions are basically vaccinated so person who is being affected in the chain or in the ring is basically vaccinated however when we talk about mass vaccine.

 V vaccine every person independent of the exposure criteria so for different diseases you have different approach so let's say polio you had a kind of mass vaccination that took place for all the kids however for small pox you have ring vaccination that helped to eradicate the smallpox the next is cleaning the environment so we have the microorganisms that also have an important role in cleaning the environment by using or the decay and the decompose material should be consumed by them or broken by them into simpler forms.

 So degrading or degenerating all the harmful substances into the atmosphere or the environment is essential our microorganisms play an important role for those now as we have talked about the benefits of microorganism so far there are definitely drawbacks these drawbacks come as harmful microorganisms so numerous disease that you have heard typhoid malaria joined us so all those are basically caused by one or the other microbes so let's talk about some of them first of all any disease which is caused by microorganism basically spoils the person's health spoils the food that a person is consuming or the skin of an animal let's say.

 So the leather of an animal so all those are known as pathogens now there are various mikroorganisation DS could spread from one person to another so if a disease is spreading from one person to another we say it's a communicable disease on the other hand if a person is suffering from disease but that disease cannot be spread to other persons we say it's a non communicable disease because it's not directly affecting or spreading to other people so let's say influence our common cold are all viral and these are communicable diseases easily being spread from one person to another by simple cough or cold

 So you have various carriers for different diseases so let's say you have female and a Phyllis that carries the parasite for basically the Plasmodium that's causing malaria so similarly you have ATS that lead to ding you so you have various insects animals that are the scarier of the diseases or as intermediate hose to lead to our disease so let's say I have a a garbage here and on this garbage you have a fly that sits in a house fly that sits in now this house fly picks up the germs and goes to an open food now this open food when consumed by a person would lead to it illness and that's how you have the cycle of disease that occurs.

 So unexposed food is harmful that's why we say uncovered food should not be consumed so these are some of the important things that we need to understand now here we have a table where we have the major diseases the organisms that lead to those diseases are how they are transmitted what are the preventive measures for those so let's say cholera typhoid TB all these are bacterial diseases on the other hand polio chicken pox measles these are viral diseases you have malaria which is protozoa disease are caused by protozoa now most of the diseases are spread by air however you have cholera which is spread by.

 Water or food you have polio that could be spread by water so you have hepatitis A that is spread by water so the mode of transmission the organism that leads to these diseases and the disease's are indeed important for you now similar to the diseases that we human being have animals do have diseases so interacts is one of the common diseases that are seen in cattle zorbo mines now anthrax is caused in human as well as the cattle population it's caused by bacteria similarly you have a foot and mouth disease in the organ and this foot-and-mouth disease is caused by virus so these were the diseases in animals now as.

 We know all living organisms have susceptibility to certain diseases so plant are also living organisms now they are also susceptible to diseases now what could be the kind of diseases in the plants so diseases in the plant the common ones could be rust on the weak that's caused by fungi then you have the citrus canker commonly on the citrus fruits now in the citrus fruit categories we put lemons oranges so all those whole fruits which are basically citrus would be considered under citrus foods and citrus fruits have a disease which is known as citrus canker this is caused by bacteria then you have on okra that's ladyfinger you have the yellow bean Mo's act that occurs and this is a viral disease or a viral disorder that could.

 My basically it's through a microorganism which is viral so these are some of the diseases that are caused by cause on to the plants so as we can see be it any living organisms human plants or animals all of them are susceptible to micro organisms these micro organisms sometimes could be useful sometimes could be harmful so that's how we understand this concept now what happens is sometimes to protect the living.

 Organism what we need to use a certain chemical so let's say there is an infection on the plant what do you need to do is you need to use certain chemicals insecticides pesticides in order to curve the growth of insects and basically curve the growth of microorganisms on that plant so that's how we try to control those however these killing chemicals or these chemicals could not be consumed by human beings so human beings what we try to do is we try to preserve the food at the first go and if not then we would try to use certain medicines to get well if you are affected by certain diseases so one is prevention one is cure so prevention occurs before the cause of disease and basically after the disease is caused you have to take certain medicines and get or get cured of so what we are talking about now is preservation or prevent prevention.

 So when I say prevention we are trying to prevent the disease itself now what do we do in that case let's say I have a bulk of food with me I have raw mangoes so if I keep those open for 10 days will they remain they will be spoiled and if I can consume that then there could be food poisoning that could be caused and I could get ill so raw mangoes if kept for 10 days would not remain as such but on the other hand I have created a pickle now and I keep this pickle for 10 days two months two years it remains as it is how is it possible this is possible by use of preservatives now what kind of preservatives do.

 We use there are various ways of using a preservatives we commonly commonly household preservatives when we talk about our salt and sugar so with salt and sugar you basically can preserve the things for at least a few days or few months so let's say for preservation of meat fish Amla raw mangoes and Tamblyn you use salt you use sugar for making jams jellies squashes so sugar basically reduces the moisture content and increases the shelf life that's the number of days the thing can remain fresh the next is.

 Chemical methods so there are chemical preservatives indeed which are edible so all chemicals are not edible certain chemicals which can consumed and which are basically authorized by the FSSA eye in India can be consumed so those let's say are sodium benzoate benzoate and sodium metabisulfite they are used in jams and squashes and once these are put into the prism these are put into jams squashes are as preservatives the shelf-life of the item increases similarly oil and vinegar is a good source of preservation.

 So pickle as you can see mostly most of the pickle you would see have a lot of oil the reason is that with this layer of oil bacteria cannot grow and multiply in that environment so all the vegetables fruits fish and meat what do you want to keep for long you need to oil it off or use vinegar similarly hot and cold treatment so boiling kills the germ that is a well-known fact and lower temperature does not promote the growth of microorganisms so either of those techniques are used for as preservation the last important one is pasteurization pasteurization is mostly done for milk so what we do is a rapid heating and a rapid cooling.

 So pasteurization basically occurs in to form the low temperature long time that is sixty two point five degrees for thirty minutes and then you have high temperature short time that 72 degree for 15 second and then freeze it so what we do is we basically pasteurize it so such a certain high temperature for a very short duration or a low temperature for a long duration would lead to pasteurization and kill the harmful bacteria is from the sample that you have and finally go to storage and packing is one of the methods by using airtight containers airtight seal vacuum bags you can increase the shelf life now talking a we.

 Have already talked about all these the next important thing that we need to focus on is nitrogen fixation as we saw in atmosphere the highest constituent of the gas that is found is nitrogen nearly 78% of the gaseous nitrogen now this 78% of the gas that is present is nitrogen this in atmosphere occurs as gassy in a gaseous form this needs to be converted into nitrogenous compound that could be consumed by plants and animals.

 So this starts with the root node use of the leguminous plants where you have the Rhizobium bacteria that occurs and you have the nitrogen fixation cycle that takes place now what happens is let's say you have the nitrogen this nitrogen is converted into nitrate nitrite into nitrate the process of conversion of to nitrate occurs where bacteria nitrosomonas and I tried to nitrate by nitrobacter so that is something very very important to understand and once you have this conversion process that's clear you can understand how in the soil as you can see in this diagram you have the compounds of nitrogen nitrogen that are present in the.

 Soil those are taken up by the plants absorbed by the animals and finally you have the atmospheric nitrogen that's released fix through lightning thunder and nitrogen fixation bacterias and ultimately comes back to the soil so that's how you have the process of nitrogen cycle that occurs in the atmosphere and we have already talked about how the nitrogen fixation takes place and the various bacterias the blue-green algae which are responsible for fixation of nitrogen also a lightening helps in the fixation of atmospheric nitrogen so these are some of the key points that we have taken from today's lecture stay tuned for more updates and science we'll be bringing more important lectures for you have a great day ahead

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