Revision Notes for CBSE Class 12 Biology Chapter 10 (Microbes in Human Welfare) - Free PDF Download
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Section–A (1 Mark Questions)
1. Name two alcoholic drinks produced in each of the following ways.
(i) By distillation
(ii) Without distillation.
Ans. (i) Whisky, brandy, rum by distillation
(ii) Wine, beer without distillation
2. What are statins? Name the microorganism that produces this substance. How is it medically important?
Ans. Statins are produced by yeasts named Monascus purpureus and are bioactive molecules. They have been commercialized as agents that aid in lowering the blood cholesterol levels. It competitively inhibits the action of the enzymes that synthesize cholesterol.
3. How do mycorrhizae function as biofertilizers? Explain with examples.
Ans. In Mycorrhiza, fungi are associated with the roots of plants. Many members of genus Glomus form mycorrhiza. This fungal symbiont absorbs water and minerals like phosphorus from the soil and provides them to the plant.
4. Give any two microbes that are useful in biotechnology.
Ans. Bacillus thuringiensis and Escherichia coli
5. Name
(i) an immune immunosuppressive agent.
(ii) microbe used in production of swiss cheese
Ans. (i) Cyclosporin A
(ii) Propionibacterium shermanii.
Section–B (2 Mark Questions)
6. How was penicillin discovered?
Ans.Penicillin was the first antibiotic that was discovered by Alexander Fleming in 1928. He returned from a holiday to find mould growing on a Petri dish of Staphylococcus bacteria. He noticed the mould seemed to be preventing the bacteria around it from growing. He soon identified that the mould produced a self-defence chemical that could kill bacteria. He named the substance penicillin.
7. What is the chemical nature of biogas? Name an organism which is involved in biogas production?
Ans. It is made up of methane (50-70%) , carbon dioxide (30-40%) with traces of nitrogen, hydrogen sulphide and hydrogen. Biogas producing bacteria are collectively called methanogens, and one such common bacterium is Methanobacterium.
8. What are biofertilizers? Give two examples.
Ans. Biofertilizers are microorganisms which bring about nutrient enrichment of soil by enhancing the ability of nutrients to crops. The microorganisms which are biofertilizers are bacteria, cyanobacteria (blue green algae) and mycorrhizal fungi.
9. Why are cyanobacteria considered useful in paddy fields?
Ans. In paddy fields, cyanobacteria serve as an important bio- fertilizer. Blue green algae not only add organic matter to the soil but also increase its fertility.
10. Why are flocs important in biological treatment of waste water?
Ans. Flocs are masses of bacteria associated with fungal filaments to form mesh-like structures. Flocs digest most of the organic material from the sludge. Thus, floc helps in reducing the BOD (Biochemical Oxygen Demand) of the effluent. This helps in further treatment of sludge.
11. What roles do enzymes play in detergents that we use for washing clothes? Are these enzymes produced from some unique microorganisms?
Ans.Lipase is used in detergent formulations because it helps in removing oily stains from laundry. Lipases are obtained from microorganisms like Candida lipolytica and Geotrichum candidum.
PDF Summary - Class 12 Biology Microbes in Human Welfare Notes (Chapter 10)
Microbes are beneficial as well as detrimental to the welfare of human beings.Microbes are utilized in many ways for human beings as explained below-
Microbes in vaccination and antibiotics/microbes in industrial products
The different products that are useful for humans are synthesized by microbes. The most common product obtained from microbes is beverages and antibiotics. For large-scale production and use of microbes in industries, The special vessels are referred to as fermenters for the use of microbes on large scale in industries.
Fermenters
Fermented Beverages are as old as civilization and are used in wine, whisky, brandy, etc. Saccharomyces cerevisiae commonly known as brewer’s yeast is the most common microbe used for fermentation. It has been used for fermenting malt-based cereals and fruit juices to produce ethanol. Different alcoholic drinks are produced based on the type of fermentation and raw material used. The drinks produced by distillation of the fermented broth are Whisky, brandy, and rum whereas wine and beer are produced through distillation.
Antibiotics are chemical substances produced using microbes against any disease-causing microbe. Penicillin, the first antibiotic discovered was obtained from mold is referred to as Penicillium notatum. For the treatment of different diseases like Whooping cough, leprosy, diphtheria, plague, etc antibiotics are required.
Some Antibiotics Produced by different Bacteria
For the production of certain chemicals like alcohols, enzymes, organic acids, etc, microbes are used. For example, Acetobacter aceti is used to produce acetic acid, Aspergillus niger is used to produce citric acid and Lactobacillus is used to produce lactic acid. Lipase enzymes can also be prepared using microbes. Streptokinase is produced by the bacterium Streptococcus which is very useful in removing clots from the blood vessels of patients who have undergone myocardial infarction leading to heart attack, thus acting as a ‘clot buster’. An immunosuppressive agent known as cyclosporin A is obtained from the fungus known as Trichoderma polysporum is used during organ transplant.
Microbes in Household Products
Lactobacillus is the bacterium found in curd that is used to convert milk into curd.
Lactic acid is produced from Lactobacillus, which partially digests milk protein and coagulates it to form curd.
A small amount of curd is needed as an inoculum in milk to begin the curd-making process.
Curd is a rich source of Vitamin B12.
Fermentation is the process of converting sugar into alcohol without the presence of oxygen.
Louis Pasteur discovered the process of fermentation.
Dough used in food items such as idli, dosa, etc., is formed by the action of bacteria, which are responsible for the fermentation of the dough, resulting in the production of carbon dioxide.
The dough used for making bread is fermented by yeast called Saccharomyces cerevisiae.
Cheese is produced by fermenting bacteria called Propionibacterium shermanii.
Different types of cheese have unique texture, taste and flavor, which are based on the types of microbes used in the fermentation process.
Roquefort cheese is ripened by growing a selected fungus on it, which provides it with a specific flavor.
Microbes in Sewage Treatment
The human excreta is a major component of this wastewater. This municipal wastewater is also called sewage. Large amounts of organic matter and microbes are present inside it. To minimize the pollution, the excreta should be treated before release. To treat the sewage, heterotrophic bacteria which are naturally present in wastewater are required. It takes place in two stages-
Primary Treatment
Secondary Treatment.
Sewage Treatment
Primary Treatment-
It is the manual removal of small and large particles through filtration and sedimentation that begins the process of primary treatment. Firstly, sequential filtration removes debris. Then the soil and small pebbles are removed by sedimentation. leftover over known as effluent is taken for secondary treatment.
Secondary Treatment or Biological Treatment
The principal effluent is sent via enormous aeration tanks, allowing aerobic bacteria to develop into flocs. These microorganisms devour the majority of the organic materials in the wastewater as they grow. This greatly reduces the effluent's BOD (biochemical oxygen demand). BOD is a measure of the amount of organic matter in water. The higher the BOD of wastewater, the more it is polluting.
After greatly reducing the BOD of sewage water, the effluent is fed into a settling tank where the bacterial 'flocs' are allowed to settle. This type of silt is known as activated sludge.
A portion of this sludge is poured back into the aeration tank to act as an inoculum.
The residual sludge is poured into enormous tanks known as anaerobic sludge digesters.
Bacteria produce a combination of gases during digestion, including methane, hydrogen sulphide and carbon dioxide. These gases combine to make biogas.
The secondary treatment plant's effluent is often discharged into natural water bodies such as rivers and streams.
Microbes in Gobar Gas Formation
Biogas is a mixture of different gases; methane percentage is the highest. Some bacteria, which grow anaerobically on cellulosic material, produce a large amount of methane along with CO2 and H2. These bacteria which produce methane as a result of anaerobic respiration are collectively called methanogens. is An example of methanogenic bacteria is Methanobacterium.
Gobar Gas Production
Microbes as Biocontrol Agents
Biocontrol is defined as the use of biological methods to control plant diseases and pests. Conventionally, pesticides and insecticides are being used for the control of diseases and pests. Hence, these chemicals are extremely toxic and harmful.
Biological Control of Pests and Diseases.
Bacillus thuringiensis (Bt) is a bacterium used as a biocontrol agent against insects/pests.
The endotoxin produced by Bt paralyses the gut of the insect/pest that consumes it.
Bt cotton is an example of a plant-produced biocontrol agent.
Trichoderma is a fungus used to control plant pathogens.
Baculoviruses are pathogens of insects and other arthropods used as biocontrol agents.
Most of the baculoviruses belong to the genus Nucleopolyhedrovirus and are ideal for narrow-spectrum actions.
Baculoviruses have no negative impacts on other organisms like plants, mammals, birds, and fish, or even on non-target insects.
Some microbes are used as bio-fertilizers.
Rhizobium is a gram-negative bacterium found in leguminous plants that helps in nitrogen fixation.
Different Biocontrol Agents
Microbes in the Human Body
Microbes colonize different parts of the human body including the skin, gut, and reproductive tract.
The most important microbes in the human body are the Gut Microflora.
The stomach microflora includes Streptococcus, Staphylococcus, etc., which are able to survive in the acidic conditions of the stomach.
The intestinal flora belongs to Enterobacteriaceae, which is required for the process of digestion and absorption, leading to increased efficiency and utility of the gut.
Certain microbes prevent the colonization of other harmful microbes and also secrete substances necessary for food digestion.
In recombinant DNA technology, viruses are used as a vector for the transmission of a required gene.
Microbes as Biofertilizers
Excess use of chemicals and their harmful effects have led farmers to switch to organic farming.
Organic farming uses biofertilizers, which are organisms that enrich the soil's nutrients.
Biofertilizers contain bacteria, fungi and cyanobacteria.
Rhizobium bacteria are found in leguminous plants and are required by plants in the absorption of nitrogen.
Other bacteria that fix nitrogen are Azospirillum and Azotobacter.
Fungi form a symbiotic relationship with roots of higher plants and absorb phosphorus from the soil and pass it to the plant.
Cyanobacteria are autotrophic microbes that fix atmospheric nitrogen, making them an important biofertilizer, especially in paddy fields.
Cyanobacteria like Anabaena, Nostoc, and Oscillatoria are widely distributed in both aquatic and terrestrial environments.
Blue-green algae add organic matter to the soil to increase its fertility.
Important Information
Microbes play a vital role in the Earth's biological system.
Not all microorganisms are pathogenic. Some of the microbes play an important role in human health.
Yoghurt is fermented milk. It is produced through the bacterial fermentation of milk.
Sewage refers to municipal wastewater and human excreta.
Living organisms are found in biofertilizers.
Microbes in Human Welfare: Class 12 Biology Chapter 10 Revision Notes Summary
The 10th chapter of this syllabus focuses on how different microorganisms help humans to prepare food products, treat waste material, manufacture medicines, etc. This chapter explains how these microorganisms can be so helpful for humans. Let us take a quick look into the overview of the revision notes Class 12 Biology Chapter 10 and how to understand and learn these concepts.
Microbes are organisms that cannot be seen with our naked eyes. They can be found almost anywhere. From a highly-acidic environment to a hyper-thermal ecosystem, you will find microbes adapting and surviving in all. There are bacteria, fungi, viruses, prions, and viroids. Moving further in Class 12 notes Microbes in Human Welfare, you will find how microbes are used in households to make certain kinds of food. For instance, milk is converted into curd using lactic acid bacteria. Fungi such as yeast are used to make bread from the wheat dough. In fact, the steps of making such things with the aid of microbes are fascinating. You will also learn how the environmental conditions actually control the formation of such microbes in these mediums.
On proceeding further in NCERT Class 12 revision notes Biology Chapter 10 solution, you will find out how microbes are used in various industrial processes. They are used for fermentation, enzyme production, antibiotic manufacturing, bioactive molecule manufacturing, organic acid production, etc. The types of microbes are different for different purposes. In fact, they can be genetically altered to make more productive new strains. A lot of examples are explained in the notes that will help you answer the specific questions in the exercise and exams. In this section, you will also find out how many eminent scientists have utilized microbes to create history by preparing something path-breaking. Alexander Fleming found penicillin, the mother of all antibiotics we have today in simple bread molds. Since the advent of penicillin, we have managed to control many diseases to a huge extent.
On proceeding further, we will also learn how microbes are used for sewage treatment. Microbes in huge numbers can reduce the amount of waste a human settlement releases every day. It helps us to manage our wastes and keep the environment clean. By studying this section in Microbes in Human Welfare Class 12 Biology revision notes, you will understand how these microorganisms play a significant role in sewage treatment and waste management. In this section, you will also learn how sewage treatment is done in modern civilization and how microbes save the day.
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FAQs on Microbes in Human Welfare Class 12 Notes CBSE Biology Chapter 10 (Free PDF Download)
1. How do microbes help us?
Microbes do not always cause diseases. Some are used to make food, manufacture medicines, and treat wastes. We should learn the good microbes that help us in these ways in Chapter 10 Class 12 Biology revision notes.
2. How microbes are used to manage waste?
If you refer to Class 12 revision notes Chapter 10, you will find out how researchers are looking for better strains of microbes to treat sewage and human waste. We are also looking for organic ways to clean rivers and rejuvenate freshwater bodies to eradicate the water crisis in the modern world.
3. What is the benefit of studying Class 12 Chapter 10 Biology using Vedantu’s revision notes?
Chapter 10 "Microbes In Human Welfare" is engaging. Students usually find Biology as a very relevant subject and this chapter is the same. It contains a detailed explanation of the topic. When students revise for their exams, they do not have the time and energy to go through such lengthy texts. Class 12 Chapter 10 Revision Notes come in handy at such a time. These notes by Vedantu are prepared by highly competent teachers and are beneficial for exams preparations. These notes are available at free of cost on the Vedantu app and on the Vedantu website.
4. What are microbes in human welfare?
Several microscopic organisms are of extreme benefit to human beings. There are several real-time applications of microbes. Microbes are helpful for human welfare in the following areas:
In household products: Eg. Lactic acid bacteria in milk
In Industrial Products: Eg. In fermented beverages, antibiotics, enzymes, etc.
In Sewage Treatment: Eg. help in reducing BOD
In Production of Biogas: Eg. Methanogens
As Biocontrol Agents: For controlling pests and diseases
As Biofertilizers: Used in organic farming
5. Is “Microbes in Human Welfare” important for NEET?
Chapter 10 teaches students various significant uses of microscopic organisms. Microbes are used in various household items, industries, and processes for human benefit. This chapter has some important concepts that are often asked in NEET examinations. Thus, students should memorize this chapter well. Moreover, it is a fairly simple chapter as compared to other chapters of Class 12 Biology. Hence it can be a highly scoring chapter. Students can refer to important questions from this chapter for NEET visit the page NEET Microbes in Human Welfare Important Questions.
6. Which microbes play a beneficial role in our stomach by checking the growth of disease-causing organisms?
Lactic acid bacteria or LAB helps in restricting the growth of disease-causing microbes in our stomach. It works by inhibiting the growth of spoilage agents. This is the bacteria responsible for turning milk into yoghurt. Probiotic products are sold widely in the markets today for promoting good gut health. These also contain useful microbes like LAB. Therefore, we can see that microbes can be very beneficial for our health as well.
7. What is “toddy”?
A southern Indian fermented drink is referred to as "Toddy". It is made by fermenting fresh sap from palm trees. The sap from palm trees contains natural yeast which leads to the fermentation process converting its glucose into alcohol. In the southern parts of India, “toddy” is a popular drink and workers often drink it at the end of their day. So, we see that yeast is another microbe that is used in fermenting drinks, leavening bread, etc.