Microbes are present everywhere even where no other life-form may occur. These are numerous, including viruses, bacteria, protozoa, fungi, viroids, prions, and other microscopic species. They can be pathogenic but play a major role in human welfare. Microbes have wide production for research and the development of various useful products in laboratories or at the industrial scale. 

• Microbes in Human Welfare comes under the chapter of Biology and Human Welfare
• In the NEET Biology Syllabus, Biology and Human Welfare carries a total weight of about 3 to 4%. 
• Microbes in Human Welfare can have a maximum of 3 questions in NEET. 

The syllabus includes other more relevant topics than Microbes in Human Welfare, and it mandates that students pay closer attention to them. Nevertheless, Microbes in Human Welfare is probably the simplest chapter in the syllabus of NEET 2021. You can get a decent score in this chapter with proper planning, and improve your total score in the NEET Biology segment.

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Microbes in Human Welfare - Household Products 

• Curd: The Lactobacillus bacteria makes lactic acid, which thickens the milk protein partially. It is also involved in increasing the level of vitamin B12. Such bacteria also appear in the intestines and monitor the development of other microbes.

• Fermented dough: For making delicacies of South India like dosa and idli. Bacteria ferment the dough because of the CO2 production.

• Bread: Bread-making using the Saccharomyces cerevisiae yeast is very common. 

• Toddy: Fermentation of the palm sap produces it.

• Other food: Soybeans, fish and bamboo shoots are fermented with microbes to produce various delicacies.

• Cheese: Various types of cheese that have different tastes and texture are made using particular microorganisms. 

Examples:

• Swiss cheese with big holes: Propionibacterium shermanii
• Roquefort cheese: Penicillium roqueforti
• Camembert cheese: Penicillium camemberti

Sample Question 

Question: Which of the following make big holes in Swiss cheese?

(a) a bacterium that produces methane gas

(b) machine

(c) a fungus that lets out a lot of gases during metabolic activities

(d) bacterium that produces large quantities of carbon dioxide

Ans: (d)

Check  Detailed NEET Biology Exam Pattern

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Microbes in Human Welfare - Industrial Products 

Microorganisms are grown in fermenters for industrial-scale output. Commercial making of numerous alcoholic drinks, antibiotics, and chemicals. 

Fermented Beverages 

• Since ancient times, saccharomyces cerevisiae (Brewer's yeast) finds it usage in producing alcoholic drinks from malted cereals and fruit juices. 

• Different types of drinks are made based on the raw material and fermentation methods used. For example, without distillation, wine and beer; and with distillation, whiskey, rum, and brandy.

Antibiotics and Vaccines 

• Penicillin was the first antibiotic.

• Discovered by Alexander Fleming, it was made from the fungus Penicillium notatum. Howard Florey and Ernest Chain extracted the antibiotic and developed it.

• It was used for treating American troops during World War II. For their research in 1945, Florey, Chain and Fleming won the Nobel Prize. 

A lot of antibiotics have been developed ever since. Examples include: 

• These days, there are several synthetic antibiotics produced. 
• Microorganisms produce vaccines that prevent weakened or attenuated disease from their surface proteins or toxins. Our body gets involved in acquiring immunity from the specific pathogen. 
• Edward Jenner created the very first smallpox vaccine.
• Several vaccines are produced for viral diseases. Example are Polio, Measles, DPT, Pneumococcal, Hepatitis-A and B, Influenza

Chemicals and Enzymes 

Several organic acids and chemicals are formed using microorganisms. Examples include: 

• Citric acid: Aspergillus niger

• Acetic acid: Acetobacter aceti

• Lactic acid: Lactobacillus

• Butyric acid: Clostridium butylicum

• Ethanol: Saccharomyces cerevisiae

Enzymes are often formed by microorganisms and are utilized for different purposes commercially.

• For example, Streptococcus creates an enzyme called streptokinase that is genetically engineered and used to eliminate clots from the blood vessels as a clot-buster. 

• Lipases: These are used in detergents and oily stain removal processes.

• Proteases and pectinases: These are used for the clarification of bottled juices.

• Several bioactive molecules are developed and can be used for different purposes. 

• Cyclosporin A: It was developed by the Trichoderma polysporum (fungus). It is an immune system suppressor, used in patients with organ transplants. 

• Statins: They are made with Monascus purpureus (yeast). It reduces cholesterol levels in the blood by inhibiting cholesterol synthesis.

Sample Question 

Question: Which among the given is the most common substrate that is utilized in distilleries for ethanol production? 

(a) Soya meal

(b) Molasses

(c) Ground gram

(d) Cornmeal

Ans: (b)

Must Read: 

• NEET Study Notes for Ecosystems
• NEET Study Notes for Human Health and Disease

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Microbes in Human Welfare - Sewage Treatment 

• Until disposal, it is essential to control wastewater, because it comprises organic matter and pathogenic bacteria. For this effect, sewage treatment plants (STPs) are used. For this, microbes (heterotrophic) that are naturally found in sewage water are utilized. 

• Primary treatment: Filtration and sedimentation are carried out in the first stage to expel floating debris and grit, that is, soil and small pebbles, respectively. Primary sludge is the solid which settles down, and the supernatant liquid is the primary effluent.

• Secondary treatment: It is sometimes called biological treatment. In wide aeration tanks, the growth of aerobic microbes is stimulated by mechanically agitating the effluent and pumping it into the air. This reduces the need for biochemical oxygen demand (BOD). BOD represents the rate of microorganisms taking up oxygen and indicates the organic matter content found in the sample. 

• The effluent is allowed to accumulate in the settling tank after a substantial reduction of BOD. The sediment of bacterial flocs (bacterial mass developing a mesh-like structure in combination with fungal filaments) and is classified as activated sludge.

• The activated sludge is digested into a digester with anaerobic sludge. This helps some of the sludge to transfer back to the aeration tank and acts as inoculum. Biogas (a mixture of gases formed from digested sludge, like methane, CO2, and H2S) could be used as fuel. 

• The secondary effluent is drained into ponds and waterways. By pouring only filtered wastewater into them, our rivers could be kept less polluted. To this end, the Government has released the action plan for the Ganga and Yamuna.

Sample Question 

Question: Which of the following stages of sewage water purification uses microbes? 

(a) Primary treatment

(b) Secondary treatment

(c) Tertiary treatment

(d) Both (1) and (2)

Ans: (b)

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Microbes in Human Welfare - Biogas Production 

• Methanogens like methanobacterium, are present in the anaerobic sludge and generate biogas in sewage treatment. This is primarily methane and a combination of other gases. Such bacteria are also found in cattle rumen and aid in cellulose digestion. 

• Gobar gas is generated from cattle dung and is used for various purposes in the villages. 

• IARI (Indian Agricultural Research Institute) and KVIC (Khadi and Village Industries Commission) put a great deal of effort into advancing biogas technology.

Sample Question

Question: Which among the given options is also called biogas?

(a) biobutanol

(b) biodiesel

(c) bioethanol

(d) biomethane

Ans: (d)

Must Read: 

• NEET Study Notes for Molecular Basis of Inheritance
• NEET Study Notes for Biological Classification
• NEET Study Notes for Reproduction

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Biocontrol of Diseases and Pests 

• Chemical pesticides and insecticides destroy species which are both dangerous and useful. A suitable method of biocontrol can be established by understanding the natural predation and interacting networks. 

• Ladybugs and dragonflies help to combat mosquitoes and aphids. 

• Bacillus thuringiensis is used for the care of insect larvae and caterpillars. Several plants can be genetically engineered, and the toxin coding gene can be inserted into the plant genome. For example, Bt-cotton is pest-resistant. 

• Trichoderma (a fungus) is used for biocontrol of various pathogens on plants. The fungus usually occurs in the roots.

• Nucleopolyhedrovirus genus' baculoviruses are exceptional agents of biocontrol. Arthropods are targeted, but they are harmful to plants and other species like birds, fish, and mammals. 

Sample Question 

Question: Which among the given options is not an example of biocontrol of diseases and pests using microbes? 

(a) Trichoderma sp. against some plant pathogens

(b) Nucleopolyhedrovirus against insects and other arthropods

(c) Ladybird beetle against aphids

(d) Bt-cotton to raise the yield

Ans: (d)

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Biofertilizers 

• The overuse of chemical fertilizers is associated with contamination and adverse effects. It is strongly recommended to use the microorganisms as biofertilizers. 

• The primary sources of biofertilizers are fungi, bacteria, and cyanobacteria. 

• The root nodules of leguminous plants produce rhizobium. They replace nitrogen in the atmosphere. Alternatively growing leguminous plants help to increase soil nitrogen content. 

• Azotobacter and Azospirillum are nitrogen-fixing, free-living bacteria found in the soil.

• The mycorrhizal fungal association also enriches soil nutrient content. For the plant, Glomus genus fungi consume phosphorus. 

• Such symbiotic relationships benefit not only from enriching the nutrient content but also from resistance to disease and tolerance to drought and salinity. 

• Some cyanobacteria can absorb nitrogen from the atmosphere. These include Nostoc, Anabaena, and Oscillatoria. Cyanobacteria are commonly used as a biofertilizer in paddy-fields. Blue-green algae are autotrophic in marine and terrestrial ecosystems and are found everywhere. By adding organic matter, they increase fertility in the soil.

Sample Question 

Question: Which among the given is not a biofertilizer?

(a) Agrobacterium

(b) Nostoc

(c) Rhizobium

(d) Mycorrhiza

Ans: (a)

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Important Topics in Microbes in Human Welfare 

Many subtopics under Microbes in Human Welfare carry more importance than others. While it is recommended that a student should study every subtopic, additional time could be dedicated to the more relevant topics provided below.

1. Usage of Microbes in Household Products 

2. Usage of Microbes in Industrial Products

3. Usage of Microbes in Sewage Treatment and Biogas Production 

4. Microbes in Biocontrol of Diseases and Pests

5. Microbes in Biofertilizers 

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Previous Year Solved Sample Questions on Microbes in Human Welfare 

1. A higher value of BOD(Biochemical Oxygen Demand) indicates which of the following? 

(a) The water is pure 

(b) The water is less contaminated 

(c) Heavily contaminated water 

(d) Higher intakes of organic matter by microbes in water

Ans: (c)

2. In which of the given processes is carbon dioxide not released?

(a) Lactate fermentation

(b) Alcoholic fermentation

(c) Aerobic respiration in animals

(d) Aerobic respiration in plants

Ans: (a)

3. Which of the given gases is produced from the anaerobic bacteria's activity on sewage?

(a) Laughing gas

(b) Propane

(c) Mustard gas

(d) Marsh gas

Ans: (c) 

4. A good producer of citric acid is? 

(a) Aspergillus

(b) Clostridium

(c) Saccharomyces

(d) Pseudomonas

Ans: (a)

5. Which of the following entries are wrongly matched? 

Ans: (c)

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Study Plan for NEET Biology 

For NEET Biology specifically, it helps a great deal to keep the entire syllabus in perspective for a good preparation plan. The time available for NEET can be prepared according to the topics' weightage. It is also critical that one adheres to the study plan and makes changes as one moves ahead. Since Microbes in Human Welfare in Biology is regarded as a simple-to-score segment, pursue the guidelines below to create an effective plan for the subject and the topic.

• Practice the elimination method.

• Make mental notes.

• Make a habit of solving questions first that you understand at first go to avoid any negative marking.

• Keep in mind your weak and strong areas.

• Candidates may use initials from the main elements in the categories to establish mnemonic phrases.

• Attempt mock tests and papers from previous years.

• Choose the best books.

• Do revision by making diagrams like charts, tables, or maps which is vital for rational understanding and data inculcation. 

• Leave no topic undone.

Read More Study Plan and Timetable for NEET 2021