Microbes in Human Welfare focuses on the beneficial role of microorganisms in everyday life, industry, agriculture, and environmental management. This category is designed for school students (Classes 11–12) , NEET aspirants , and undergraduate learners , with strong emphasis on NCERT-based concepts and exam relevance.
In this section, you will study:
Microbes in household products such as curd, bread, and fermented foods
Role of microbes in industrial products like antibiotics, enzymes, and organic acids
Microorganisms in sewage treatment and waste management
Use of microbes in biogas production and biofertilizers
Microbes as biological control agents
NCERT-based explanations, flowcharts, diagrams, MCQs, and exam-oriented questions
The content is structured to build clear conceptual understanding , improve application-based answers , and help students score well in school examinations, NEET, and undergraduate assessments .
Understand how microorganisms contribute positively to human welfare and play a vital role in sustainable living.
Q. What is the primary benefit of using nitrogen-fixing bacteria in agriculture?
A.
They increase soil acidity
B.
They enhance soil structure
C.
They provide a natural source of nitrogen
D.
They promote plant disease resistance
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Solution
Nitrogen-fixing bacteria convert atmospheric nitrogen into a form that plants can use, reducing the need for chemical fertilizers.
Correct Answer:
C
— They provide a natural source of nitrogen
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Q. What is the primary function of actinomycetes in soil?
A.
Nitrogen fixation
B.
Decomposition of organic matter
C.
Photosynthesis
D.
Pathogen resistance
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Solution
Actinomycetes play a crucial role in the decomposition of organic matter, contributing to nutrient cycling in soil.
Correct Answer:
B
— Decomposition of organic matter
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Q. What is the primary function of probiotics in human health?
A.
To enhance digestion
B.
To produce vitamins
C.
To increase appetite
D.
To cause infections
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Solution
Probiotics are beneficial bacteria that help maintain a healthy gut microbiome and enhance digestion.
Correct Answer:
A
— To enhance digestion
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Q. What is the role of actinobacteria in soil health?
A.
They cause plant diseases
B.
They decompose organic matter
C.
They fix carbon dioxide
D.
They produce antibiotics
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Solution
Actinobacteria play a crucial role in decomposing organic matter, contributing to nutrient cycling in soil.
Correct Answer:
B
— They decompose organic matter
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Q. What is the role of Rhizobium bacteria in legume plants?
A.
Decomposing organic matter
B.
Fixing atmospheric nitrogen
C.
Promoting root growth
D.
Producing secondary metabolites
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Solution
Rhizobium bacteria form nodules on legume roots and fix atmospheric nitrogen, benefiting the plant.
Correct Answer:
B
— Fixing atmospheric nitrogen
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Q. What is the role of Rhizobium in legume plants?
A.
Decomposing organic matter
B.
Fixing atmospheric nitrogen
C.
Promoting root growth
D.
Enhancing photosynthesis
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Solution
Rhizobium bacteria form nodules on legume roots and fix atmospheric nitrogen, benefiting the plant.
Correct Answer:
B
— Fixing atmospheric nitrogen
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Q. What is the role of Rhizobium in plant ecology?
A.
Decomposing organic matter
B.
Forming symbiotic relationships with legumes
C.
Causing plant diseases
D.
Producing antibiotics
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Solution
Rhizobium bacteria form symbiotic relationships with legume roots, fixing nitrogen and improving soil fertility.
Correct Answer:
B
— Forming symbiotic relationships with legumes
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Q. What is the significance of endophytes in plants?
A.
They cause diseases
B.
They enhance plant growth
C.
They compete with roots for nutrients
D.
They are harmful to humans
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Solution
Endophytes are beneficial microbes that live within plant tissues and can enhance growth and stress resistance.
Correct Answer:
B
— They enhance plant growth
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Q. What is the significance of using biopesticides derived from microbes?
A.
They are more toxic than chemical pesticides
B.
They can target specific pests without harming beneficial organisms
C.
They are less effective than synthetic pesticides
D.
They require more frequent application
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Solution
Biopesticides derived from microbes can effectively target specific pests while minimizing harm to non-target organisms.
Correct Answer:
B
— They can target specific pests without harming beneficial organisms
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Q. What is the significance of using microbes in bioremediation?
A.
They increase soil fertility
B.
They degrade environmental pollutants
C.
They enhance plant growth
D.
They produce biofuels
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Solution
Microbes in bioremediation are used to degrade environmental pollutants, helping to clean up contaminated sites.
Correct Answer:
B
— They degrade environmental pollutants
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Q. What is the significance of using probiotics in agriculture?
A.
They increase crop yield
B.
They enhance soil pH
C.
They promote weed growth
D.
They reduce water retention
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Solution
Probiotics can enhance crop yield by improving soil health and plant growth through beneficial microbial interactions.
Correct Answer:
A
— They increase crop yield
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Q. What is the significance of using Trichoderma in agriculture?
A.
It enhances photosynthesis
B.
It acts as a biocontrol agent
C.
It increases soil salinity
D.
It promotes root growth
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Solution
Trichoderma is a fungus used as a biocontrol agent to suppress plant pathogens and promote plant health.
Correct Answer:
B
— It acts as a biocontrol agent
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Q. What role do mycorrhizal fungi play in plant health?
A.
They decompose organic matter
B.
They fix atmospheric nitrogen
C.
They enhance nutrient absorption
D.
They produce plant hormones
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Solution
Mycorrhizal fungi form symbiotic relationships with plant roots, enhancing nutrient absorption, particularly phosphorus.
Correct Answer:
C
— They enhance nutrient absorption
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Q. What type of symbiotic relationship exists between plants and mycorrhizal fungi?
A.
Parasitism
B.
Commensalism
C.
Mutualism
D.
Competition
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Solution
The relationship between plants and mycorrhizal fungi is mutualistic, as both parties benefit from the association.
Correct Answer:
C
— Mutualism
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Q. Which microbe is known for producing the antibiotic penicillin?
A.
Bacillus cereus
B.
Penicillium chrysogenum
C.
Streptomyces griseus
D.
Escherichia coli
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Solution
Penicillium chrysogenum is the mold from which the antibiotic penicillin is derived, used to treat bacterial infections.
Correct Answer:
B
— Penicillium chrysogenum
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Q. Which microbe is primarily responsible for the fermentation of bread?
A.
Lactobacillus
B.
Saccharomyces cerevisiae
C.
Aspergillus niger
D.
Clostridium botulinum
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Solution
Saccharomyces cerevisiae, or baker's yeast, is responsible for the fermentation process in bread making.
Correct Answer:
B
— Saccharomyces cerevisiae
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Q. Which microbe is primarily responsible for the fermentation of sauerkraut?
A.
Lactobacillus
B.
Bacillus
C.
Clostridium
D.
Staphylococcus
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Solution
Lactobacillus species are key players in the fermentation process of sauerkraut, converting sugars into lactic acid.
Correct Answer:
A
— Lactobacillus
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Q. Which microbe is primarily responsible for the fermentation process in bread making?
A.
Lactobacillus
B.
Saccharomyces cerevisiae
C.
Rhizobium
D.
Clostridium
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Solution
Saccharomyces cerevisiae, or baker's yeast, ferments sugars to produce carbon dioxide and alcohol, causing bread to rise.
Correct Answer:
B
— Saccharomyces cerevisiae
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Q. Which microbe is used in the production of vinegar?
A.
Lactobacillus
B.
Acetobacter
C.
Saccharomyces
D.
Bacillus
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Solution
Acetobacter is a genus of bacteria that converts ethanol into acetic acid, the main component of vinegar.
Correct Answer:
B
— Acetobacter
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Q. Which of the following is a benefit of using composting in agriculture?
A.
It increases soil erosion
B.
It reduces soil fertility
C.
It enhances soil microbial diversity
D.
It requires chemical additives
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Solution
Composting enriches soil with organic matter and enhances microbial diversity, improving soil health.
Correct Answer:
C
— It enhances soil microbial diversity
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Q. Which of the following is a benefit of using microbes in bioremediation?
A.
They increase soil erosion
B.
They can degrade pollutants
C.
They promote invasive species
D.
They reduce biodiversity
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Solution
Microbes used in bioremediation can degrade pollutants, helping to clean up contaminated environments.
Correct Answer:
B
— They can degrade pollutants
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Q. Which of the following is a benefit of using microbes in composting?
A.
They increase greenhouse gas emissions
B.
They speed up the decomposition process
C.
They reduce soil fertility
D.
They promote weed growth
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Solution
Microbes in composting break down organic matter quickly, speeding up the decomposition process and producing nutrient-rich compost.
Correct Answer:
B
— They speed up the decomposition process
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Q. Which of the following is a benefit of using probiotics in agriculture?
A.
They increase crop yield
B.
They reduce soil pH
C.
They promote pest resistance
D.
They enhance nutrient uptake
Show solution
Solution
Probiotics can enhance crop yield by improving soil health and plant growth.
Correct Answer:
A
— They increase crop yield
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Q. Which of the following is a characteristic of rhizobia?
A.
They are aerobic bacteria
B.
They form nodules on plant roots
C.
They are pathogenic to plants
D.
They are unicellular fungi
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Solution
Rhizobia are bacteria that form symbiotic nodules on the roots of leguminous plants, facilitating nitrogen fixation.
Correct Answer:
B
— They form nodules on plant roots
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Q. Which of the following is a method of biocontrol using microbes?
A.
Using chemical pesticides
B.
Introducing beneficial nematodes
C.
Applying synthetic fertilizers
D.
Utilizing Bacillus thuringiensis
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Solution
Bacillus thuringiensis is a bacterium used as a biocontrol agent to target specific insect pests.
Correct Answer:
D
— Utilizing Bacillus thuringiensis
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Q. Which of the following microbes is commonly used in the production of yogurt?
A.
Lactobacillus
B.
Escherichia coli
C.
Bacillus subtilis
D.
Saccharomyces cerevisiae
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Solution
Lactobacillus is a genus of bacteria that ferments lactose to produce lactic acid, which is essential in yogurt production.
Correct Answer:
A
— Lactobacillus
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Q. Which of the following microbes is essential for the fermentation process in bread making?
A.
Yeast
B.
Mold
C.
Bacteria
D.
Virus
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Solution
Yeast, particularly Saccharomyces cerevisiae, ferments sugars to produce carbon dioxide, causing the bread to rise.
Correct Answer:
A
— Yeast
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Q. Which of the following microbes is used in the production of vinegar?
A.
Lactobacillus
B.
Acetobacter
C.
Bacillus
D.
Clostridium
Show solution
Solution
Acetobacter is a genus of bacteria that converts ethanol into acetic acid, the main component of vinegar.
Correct Answer:
B
— Acetobacter
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Q. Which type of bacteria is commonly used in the production of yogurt?
A.
Lactobacillus
B.
Escherichia
C.
Streptococcus
D.
Bacillus
Show solution
Solution
Lactobacillus species are lactic acid bacteria that ferment lactose to produce yogurt.
Correct Answer:
A
— Lactobacillus
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Q. Which type of microbe is primarily responsible for the fermentation process in bread making?
A.
Lactic acid bacteria
B.
Yeasts
C.
Molds
D.
Actinomycetes
Show solution
Solution
Yeasts, particularly Saccharomyces cerevisiae, are responsible for fermentation in bread making, producing carbon dioxide that helps the dough rise.
Correct Answer:
B
— Yeasts
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