NCERT Solution Microbes in Human Welfare Class 12

NCERT Solution Microbes in Human Welfare class 12 Biology Chapter 10

NCERT Book Chapter 10 There are all the topics covered related to this lesson read carefully and clear your all doubts.

Microbes in Human Welfare Class 12 Introduction

Microbes are tiny organisms that cannot be seen with the naked eye. These include bacteria, fungi, and viruses. Now you might be asking, “How can these little animals help us humans?” Well, it turns out that they play a big role in making our lives better! In class 12 we learn how these organisms are our friends in many ways. They help in the production of medicine, in the treatment of wastewater, and in the production of foodstuffs such as curds and bread.

and even in cleaning up environmental messes. So, even though we can’t see them, these tiny microbes are like little helpers making our world healthier and happier.

Microbes in human welfare class 12 definition

Microbes in human health refer to small organisms, such as bacteria and fungi, that have a positive impact on human life. These organisms are useful in areas such as medicine, agriculture, and environmental protection. They help manufacture medicines, produce food, and treat waste. Simply put, these little guys are our helpful friends who work behind the scenes to improve our health, food production, and the environment.

Microbes in Human Welfare Class 12 Important Notes

Microbes are small organisms such as bacteria, fungi, and viruses. They play an important role in many aspects of human life.

Microbes are used to make antibiotics and vaccines, which help us fight disease and illness.

Food production:
Fermentation by microbes involved in food production processes such as yogurt, bread and pickles.

Sewage Treatment:
Bacteria play an important role in sewage treatment plants, breaking down organic matter and purifying water.

Biocontrol Agents:
Some microbes act as biocontrol agents, helping to control pests in agriculture without being toxic.

Nitrogen fixation:
Nitrogen-fixing bacteria convert nitrogen in the atmosphere into a form that plants can use, increasing soil fertility.

Biogas Production:
Methane-producing microbes are used in the production of biogas, a renewable energy source.

Environmental cleanliness:
Microbes participate in bioremediation, helping to clean up oil spills and reducing pollutants in the environment.

Knowledge of Antibiotics:
Misuse of antibiotics has led to antibiotic resistance, emphasizing the need for responsible use to preserve their effectiveness.

Science and Biotechnology:
Microbes have been widely studied for their potential in biotechnological applications, from enzyme production to genetic engineering.

Microbes in Human Welfare Class 12 Explanation

play a vital role in Earth’s biological systems, alongside visible plants and animals. In your Class XI studies, you delved into the diversity of living organisms. Can you recall which Kingdoms house microorganisms, particularly those that are microscopic? Microbes are

ubiquitous—found in soil, water, air, and within the bodies of humans, animals, and plants. They even thrive in extreme environments where other life forms may struggle to survive, such as deep within geysers, under layers of snow, and in highly acidic conditions.

Microbes exhibit diversity, including protozoa, bacteria, fungi, microscopic plant viruses, viroids, and prions, which are proteinaceous infectious agents. Figures 10.1 and 10.2 illustrate some of these microbes. Certain microbes, like bacteria and many fungi, can be cultivated on nutritive media to form visible colonies (Figure 10.3), aiding in studies on microorganisms.

In Chapter 8, you learned that microbes can cause various diseases in humans, animals, and plants. However, not all microbes are harmful; many contribute positively to human welfare. This chapter explores some essential ways in which microbes benefit us.

Microbes in Human Welfare Class 12

10.1 MICROBES IN HOUSEHOLD PRODUCTS Microbes, like Lactobacillus and other lactic acid bacteria (LAB), are widely used in everyday products. For instance, curd is produced from milk through the growth of LAB, enhancing its nutritional quality. LAB in our stomachs also play a beneficial role in combating disease-causing microbes. Bacteria contribute to the fermentation process in making foods like dosa, idli, and bread, with the production of CO2 gas. Traditional drinks like ‘toddy’ and fermented foods like cheese, fish, soybeans, and bamboo shoots involve microbial fermentation.

10.2 MICROBES IN INDUSTRIAL PRODUCTS Microbes play a crucial role in industrial processes, synthesizing valuable products like beverages and antibiotics. Large-scale production involves cultivating microbes in fermentors.

10.3 MICROBES IN WASTE TREATMENT Microbes are instrumental in treating various types of waste. Sewage treatment plants utilize microorganisms to break down organic matter, purifying water before its release. Similarly, in solid waste management, microbial decomposition plays a vital role.

10.4 MICROBES AS BIOCONTROL AGENTS Microbes serve as biocontrol agents in agriculture, helping control plant diseases. The use of beneficial microbes can reduce the dependence on harmful chemical pesticides, promoting sustainable and eco-friendly farming practices.

10.5 MICROBES IN BIOGAS PRODUCTION Certain microbes participate in the anaerobic digestion of organic matter to produce biogas. Methane-producing bacteria break down organic materials, such as agricultural waste or sewage sludge, generating a renewable energy source.

10.6 MICROBES IN BIOTECHNOLOGY Advancements in biotechnology heavily rely on microbes. Genetic engineering techniques use microbes to produce valuable proteins, enzymes, and pharmaceuticals. Microbes are employed in the synthesis of biofuels, contributing to sustainable energy solutions.

Microbes in Human Welfare Class 12

Biocontrol refers to the utilization of biological methods for managing plant diseases and pests. In modern society, the prevalent approach to these issues involves the extensive use of chemicals such as insecticides and pesticides.

However, these chemical solutions pose significant risks as they are toxic and harmful to both humans and animals, leading to environmental pollution in soil, groundwater, fruits, vegetables, and crops. The application of weedicides further contributes to soil pollution.

Biological control, as an alternative, focuses on the natural predation of pests rather than relying on chemical interventions. Organic farming embraces the idea that biodiversity promotes overall health and sustainability.

Organic farmers aim to establish systems where insects, often considered pests, are not eliminated but instead maintained at manageable levels through a dynamic ecological balance. This approach stands in contrast to conventional farming practices that frequently resort to chemical means, affecting both harmful and beneficial organisms.

The holistic approach of biological farming aims to understand the intricate interactions within field fauna and flora. Organic farmers believe in maintaining a balance rather than indiscriminately eliminating pests, recognizing their role in supporting beneficial predatory and parasitic insects.

This approach reduces dependence on toxic chemicals and pesticides. Organic farmers emphasize understanding the life forms, life cycles, feeding patterns, and habitats of both predators and pests to implement effective biocontrol measures.

Various organisms, such as Ladybirds and Dragonflies, serve as natural predators to control aphids and mosquitoes. Microbial biocontrol agents, like Bacillus thuringiensis (Bt) bacteria, are used to combat butterfly caterpillars.

Genetic engineering has allowed scientists to introduce B. thuringiensis toxin genes into plants, creating pest-resistant varieties like Bt-cotton.

In plant disease treatment, the fungus Trichoderma is being developed as a biological control agent against various plant pathogens. Baculoviruses, specifically those in the Nucleopolyhedrovirus genus, target insects and arthropods, providing species-specific

insecticidal applications without harming non-target organisms. These approaches contribute to integrated pest management and environmentally sensitive practices in agriculture.

Microbes in Human Welfare Class 12 Summary

Microbes play a crucial role in various aspects of our lives, offering numerous benefits. Notably, lactic acid bacteria (LAB) are essential in transforming milk into curd, while yeast like Saccharomyces cerevisiae ferments dough for bread. Microbes contribute to the fermentation of dishes like idli and dosa.

In cheese production, bacteria and fungi provide distinctive textures and flavors. Industrially, microbes are involved in producing lactic acid, acetic acid, and alcohol, serving diverse industrial processes. Additionally, antibiotics derived from microbes, such as penicillins, are instrumental in combating disease-causing microbes, significantly contributing to the control of infectious diseases like diphtheria and whooping cough.

Microbes have been integral in various applications beneficial to humans for over a century. They play a crucial role in treating sewage through processes like activated sludge formation, contributing to water recycling in nature. Methanogens, as they degrade plant waste, produce methane (biogas) that serves as an energy source in rural areas. Additionally,

microbes are employed in biocontrol measures to combat harmful pests, reducing reliance on toxic pesticides. As there’s a growing emphasis on environmental sustainability, the shift towards biofertilizers over chemical fertilizers is encouraged. The diverse applications of microbes highlight their significant role in promoting the welfare of human society.

Microbes in Human Welfare Class 12 Question and Answer

Question:1 Name some traditional Indian foods made of wheat, rice, and Bengal gram (or their products) that involve use of microbes


Some Indian food made of wheat, rice, and Bengal gram are:

(i) Wheat: Bread, Bhatura and Cake are made of Wheat

(ii) Rice: Idli, Dosa and Uttapam are made of Rice

(iii) Bengal gram: Dhokla and Khandvi are made of Bengal gram

Question:2 Name any two species of fungus, which are used in the production of antibiotics.


Several microbes produce antibiotics, that kill other microbes which cause diseases. These antibiotics are typically acquired from fungi and bacteria. Two species of fungus that are used in the production of antibiotics are:

(i) Penicillin – the fungal source is Penicillium notatum

(ii) Cephalosporin – the fungal source is Cephalosporium acremonium

Question:3 What are microbes?

Answer: Microbes are tiny living organisms that we can’t see with our naked eyes. They include bacteria, fungi, and viruses.

Question:4 Are all microbes harmful?

Answer: No, not all microbes are harmful. Many microbes are helpful and play important roles in various aspects of life.

Question:5 How do microbes benefit us?

Answer: Microbes benefit us in many ways. They help in making curd from milk, fermenting dough for bread, and even producing antibiotics to fight diseases.

Question:6 How are lactic acid bacteria (LAB) useful?

Answer: LAB, like those in curd, are helpful microbes. They convert milk into curd, improving its nutritional value, and also assist in our stomach to prevent harmful microbes.

Question:7 What is the role of microbes in the environment?

Answer: Microbes help in treating sewage, producing biogas (methane), and recycling plant waste. They contribute to maintaining the balance of nature.

Question:8 Can microbes be used for pest control?

Answer: Yes, microbes can be used for biocontrol to manage pests without harmful chemicals. For example, bacteria like Bacillus thuringiensis can control caterpillars

Question:9 How do microbes contribute to medicine?

Answer: Microbes produce antibiotics like penicillin, which help in treating infectious diseases. They have played a crucial role in controlling illnesses.

Question:10 What is the significance of biogas produced by microbes?

Answer: Microbes, specifically methanogens, produce biogas from plant waste. This biogas is used as a source of energy, especially in rural areas.

Microbes in Human Welfare Class 12 MCQ

Question:1 What is the primary role of lactic acid bacteria (LAB) in the production of curd?

  1. A) Increase acidity
  2. B) Coagulate and digest milk proteins
  3. C) Enhance color
  4. D) Reduce nutritional value

Question:2 Which yeast is commonly used in fermenting dough for making bread?

  1. A) Candida albicans
  2. B) Saccharomyces cerevisiae
  3. C) Aspergillus niger
  4. D) Rhizopus stolonifer

Question:3 What is the byproduct of microbial fermentation that causes the dough to puff up?

  1. A) Oxygen
  2. B) Nitrogen
  3. C) Carbon dioxide (CO2)
  4. D) Methane

Question:4 Which of the following diseases can be treated using antibiotics produced by microbes?

  1. A) Malaria
  2. B) Tuberculosis
  3. C) Diabetes
  4. D) Hypertension

Question:5 What is the role of methanogens in the microbial world?

  1. A) Produce antibiotics
  2. B) Decompose plant waste
  3. C) Cause diseases
  4. D) Fix nitrogen

Question:6 What process involves the use of microbes to treat sewage?

  1. A) Photosynthesis
  2. B) Fermentation
  3. C) Activated sludge formation
  4. D) Respiration

Question:7 Which bacteria are commonly used in biocontrol to manage pests?

  1. A) Escherichia coli
  2. B) Bacillus thuringiensis (Bt)
  3. C) Staphylococcus aureus
  4. D) Streptococcus pneumonia

Question:8 What is the primary source of energy in rural areas produced by microbes?

  1. A) Solar energy
  2. B) Wind energy
  3. C) Biogas
  4. D) Hydroelectric power

Question:9 What do we call the process of using microbes to enhance the fertility of soil?

  1. A) Biocontrol
  2. B) Bioremediation
  3. C) Biofertilization
  4. D) Biodegradation

Question:10 In genetic engineering, which microbe has its toxin genes introduced into plants for insect resistance?

  1. A) Escherichia coli
  2. B) Bacillus subtilis
  3. C) Saccharomyces cerevisiae
  4. D) Bacillus thuringiensis (Bt)

MCQ Answer

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