biology-class-12-unit-10-chapter-02-biologyin-human-welfare-microbesin-human-welfare-lecture-2-2-sneurfpdlfm

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<h3 id="successlets-recapsuccess"><Success>Lets recap!</Success></h3>
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<p><strong>In our previous lesson of this chapter “Microbes in human welfare”, we discussed the following aspects</strong></p>
<ul>
<li>
<p>Certain characteristics of microbes</p>
</li>
<li>
<p>Usefulness of microbes in our everyday houshold products like curd, fermented dough preparations, fermented food, fermented
sap of palm used as traditional drink “Toddy or Tadí, swiss cheese and roquefort cheese”</p>
</li>
<li>
<p>Harnessing of microbes in industries for commercial production of fermented beverages, antibiotics, organic acids, enzymes and bioactive molecules</p>
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<li>
<p>Role of microbes in sewage treatment</p>
</li>
</ul>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-10-chapter-02-biologyin-human-welfare-microbesin-human-welfare-lecture-2_2-sneurfpdlfm-022-0350.4.jpg"></p>
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<h3 id="successmicrobes-in-production-of-biogassuccess"><Success>Microbes in production of biogas</Success></h3>
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<ul>
<li>
<p>Microbes produces gases as end product during growth and metabolism</p>
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<li>
<p>The type of gas depend on microbes and organir substrate they utilise</p>
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<li>
<p>Yeast produce carbon dioxide as a result of anaerobic respiration</p>
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<p>Certain bacteria growing anaerobically on cellulorie material produce large amount of methane along with $CO_2$ and $H_2$</p>
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<p>These are collectively called Methanogen<br>
<strong>Example-</strong> <em>Methanobacterium</em>, <em>Methanococcus</em></p>
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<li>
<p>These bacteria are also present in the rumen of cattles and help in digestion of cellulosic material present in their food</p>
</li>
</ul>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-10-chapter-02-biologyin-human-welfare-microbesin-human-welfare-lecture-2_2-sneurfpdlfm-029-0622.8.jpg"></p>
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<h3 id="successmicrobes-in-production-of-biogassuccess-2"><Success>Microbes in production of biogas</Success></h3>
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<ul>
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<p>A typical biogas plant consist of a concrete tank (10-15 feet deep) in which bio wastes are collected and a slurry of dung is fed</p>
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<p>A floating cover is placed over the tank</p>
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<p>The plant has an outlet which is connected to a pipe to supply biogas to nearby homes</p>
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<p>The spent slurry is removed through another outlet and may be used as mannure</p>
</li>
</ul>
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<img src="https://imagedelivery.net/YfdZ0yYuJi8R0IouXWrMsA/f9422613-2c88-43bb-1cf3-1de408a14b00/public" width="100%">

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<h3 id="successmicrobes-as-biofertiliserssuccess-1"><Success>Microbes as biofertilisers</Success></h3>
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<ul>
<li>
<p><em>Azospirullum</em> and <em>Azotobacter</em> are free living nitrogen fixing bacteria</p>
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<p>Mycorrhiza are symbiotic association of fungus with roots of higher plants</p>
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<p>These not only help in absorption of phosphorous but also provide resistance to root borne pathogens, tolerance to salinity and drought, and an overall increase in plant growth and development</p>
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<p>Cyanobacteria such as <em>Anabaena</em>, <em>Nostoc</em>, <em>Oscillatoria</em> can fix atmospheric nitrogen, they serve as important biofertilisers in paddy fields they also add organic matter to soil</p>
</li>
</ul>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-10-chapter-02-biologyin-human-welfare-microbesin-human-welfare-lecture-2_2-sneurfpdlfm-02.jpg"></p>
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<h3 id="successlets-discusssuccess-2"><Success>Lets discuss!</Success></h3>
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<p><strong>Question 3.</strong> Find out from magazines or newspapers about any latest research on beneficial aspects of microbes</p>
<p><strong>Answer.</strong> Removal of oil spills,Toxic metals can be converted into non toxic forms</p>
<p><strong>Question 4.</strong> Can you suggest some examples in nature where microbes have proved to be beneficial</p>
<p><strong>Answer.</strong> Nitrogen fixing bacterias,Decomposition of dead and decayed matter by bacteria and fungi</p>
<p><strong>Question 5.</strong> Some of the archaeabacteria are extremophiles. How are they able to survive in such extreme conditions?</p>
<p><strong>Answer.</strong> Because of cell wall structure</p>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-10-chapter-02-biologyin-human-welfare-microbesin-human-welfare-lecture-2_2-sneurfpdlfm-05.jpg"></p>
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<h3 id="successlets-discuss-textbook-questionssuccess"><Success>Lets discuss textbook questions!</Success></h3>
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<p><strong>Question 1.</strong> Do you think microbes can also be used as source of energy? If yes, how?</p>
<p><strong>Answer.</strong> Microbes present in activated sludge are digested anaerobically to generate biogas which can be used as a renewable source of energy some microbes have been discovered to produce biofuels/biodiesels</p>
<p><strong>Question 2.</strong> Microbes can be used to decrease the use of chemical fertilisers and pesticides. Explain how this can be accomplished?</p>
<p><strong>Answer.</strong> Bacillus thuringienesis,trichoderma,baculoviruses as biocontrol agents and nitrogen fixing bacterias, cyanobacteria, mycorrhiza as biofertilisers</p>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-10-chapter-02-biologyin-human-welfare-microbesin-human-welfare-lecture-2_2-sneurfpdlfm-06.jpg"></p>
<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-10-chapter-02-biologyin-human-welfare-microbesin-human-welfare-lecture-2_2-sneurfpdlfm-07.jpg"></p>
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<h3 id="successlets-discuss-textbook-questionssuccess-1"><Success>Lets discuss textbook questions!</Success></h3>
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<p><strong>Question 3.</strong> Three water samples namely river water, untreated sewage water and secondary effluent discharged from a sewage treatment plant were subjected to BOD test. The samples were labelled A,B and C, but the laboratory attendant did not note which was which.The BOD values of the three samples A,B and C were recorded as 20 mg/ml, 8 mg/ml, and 400 mg/ml,respectively. Which sample of the water is most polluted? Can you assign the correct label to each assuming the river water is relatively clean?</p>
<p><strong>Answer.</strong> Greater the BOD, greater is the pollution so, sample C having 400 mg/ml BOD is untreated sewage sample B having BOD 8 mg ml is river water sample A having BOD 20 mg ml is secondary effluent discharged from a sewage treatment plant</p>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-10-chapter-02-biologyin-human-welfare-microbesin-human-welfare-lecture-2_2-sneurfpdlfm-07.jpg"></p>
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<h3 id="successlets-discuss-textbook-questionssuccess-4"><Success>Lets discuss textbook questions!</Success></h3>
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<p><strong>Question 6.</strong> Arrange the following in the decreasing order (most important first) of their importance, for the welfare of human society.</p>
<p><strong>Answer.</strong> Biogas, citric acid, penicillin and curd</p>
<ol>
<li>Penicillin - antibiotic used to cure many bacterial diseases</li>
<li>Biogas - good source of energy in rural areas</li>
<li>Citric acid - used as preservative for many food items</li>
<li>Curd - good food and easily digested</li>
</ol>
<p><strong>Question-7</strong> How do biofertilizers enrich the fertility of soil?</p>
<p><strong>Answer.</strong> By replenishing the soil with nitrogen phosphorous and other nutrients</p>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-10-chapter-02-biologyin-human-welfare-microbesin-human-welfare-lecture-2_2-sneurfpdlfm-08.jpg"></p>
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<h3 id="successlets-evaluatesuccess"><Success>Lets evaluate!</Success></h3>
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<p><strong>Question 1.</strong> The free living fungus used as a biological control against several pathogens of plants</p>
<ul>
<li><em>Trichoderma</em></li>
<li><em>Penicilliuum</em></li>
<li><em>Frankia</em></li>
<li><em>Saccharomyces</em></li>
</ul>
<p><strong>Question 2.</strong> The excreta of cattle, commonly called ‘gobar’ is rich in</p>
<ul>
<li><em>Rhizobium</em></li>
<li><em>Methanobacterium</em></li>
<li><em>Pseudomonas putida</em></li>
<li><em>Bacillus</em> species</li>
</ul>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-10-chapter-02-biologyin-human-welfare-microbesin-human-welfare-lecture-2_2-sneurfpdlfm-10.jpg"></p>
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<h3 id="successlets-evaluatesuccess-1"><Success>Lets evaluate!</Success></h3>
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<p><strong>Question 3.</strong> Which of the following can be the application of fermentation?</p>
<ul>
<li>Tanning of leather</li>
<li>Curing of tea</li>
<li>Production of wine</li>
<li>All of the above</li>
</ul>
<p><strong>Question 4.</strong> A bioreactor is</p>
<ul>
<li>Hybridoma</li>
<li>Culture containing radioactive isotopes</li>
<li>Culture for synthesis of new chemicals</li>
<li>Fermentation tank</li>
</ul>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-10-chapter-02-biologyin-human-welfare-microbesin-human-welfare-lecture-2_2-sneurfpdlfm-10.jpg"></p>
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<h3 id="successlets-evaluatesuccess-2"><Success>Lets evaluate!</Success></h3>
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<p><strong>Question 5.</strong> High value of BOD shows</p>
<ul>
<li>Water is normal</li>
<li>Water is highly polluted</li>
<li>Water is less polluted</li>
<li>None of these</li>
</ul>
<p><strong>Question 6.</strong> Spirulina is a</p>
<ul>
<li>Edible fungus</li>
<li>Biofertiliser</li>
<li>Biocontrol</li>
<li>Single cell protein</li>
</ul>
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