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Q5:
In which way have microbes played a major role in controlling diseases caused by harmful bacteria?
Solution :
Step 1: Theoretical Foundation of Antibiotic Production
Microbes, specifically certain bacteria and fungi, act as the primary biological agents for controlling pathogenic (harmful) bacteria through the synthesis of secondary metabolites known as antibiotics. These substances function by either inhibiting the metabolic processes of pathogenic bacteria (bacteriostatic) or by directly inducing bacterial cell death (bactericidal).
Step 2: Mechanism of Action and Microbial Sources
The control mechanism relies on the selective toxicity of antibiotics, which target specific bacterial structures—such as cell wall synthesis or protein synthesis—that are absent or distinct in the human host.
| Microbial Source | Type of Microbe | Representative Antibiotic | Target Mechanism |
|---|---|---|---|
| Penicillium notatum | Fungi | Penicillin | Inhibition of Peptidoglycan cell wall synthesis |
| Streptomyces griseus | Actinomycetes | Streptomycin | Inhibition of bacterial protein synthesis (30S subunit) |
| Bacillus subtilis | Bacteria | Bacitracin | Interference with cell wall precursor transport |
Step 3: Clinical Application and Global Impact
The systematic use of these microbial products has transformed clinical medicine:
- Broad-spectrum efficacy: Many antibiotics derived from Streptomyces species are effective against a wide array of Gram-positive and Gram-negative bacteria [Per pharmacological classification criteria].
- Prevention of Complications: By suppressing pathogenic bacterial growth, antibiotics prevent secondary infections and systemic spread (sepsis) following surgery or trauma.
- Historical Context: The discovery of penicillin by Alexander Fleming in 1928 serves as the benchmark for antibiotic utility in controlling infectious diseases like pneumonia, diphtheria, and tuberculosis [Reference: Historical Review of Antimicrobial Chemotherapy].
Step 4: Schematic Illustration of Microbial Inhibition
Step 5: Synthesizing the Role
Microbes function as the architects of modern antimicrobial therapy. By harvesting these compounds, humanity has effectively neutralized harmful bacterial populations that were previously fatal. This interaction is rooted in antibiosis—a biological interaction where one organism negatively impacts the survival or metabolic activity of another [Per ecological theory of microbial competition].
Final Solution: Microbes contribute to controlling harmful bacteria primarily through the mass production of antibiotics—secondary metabolites that selectively inhibit bacterial cell wall synthesis or essential protein translation—thereby providing effective therapeutic interventions against infectious diseases.
More Questions from Class 12 Biology Microbes in Human Welfare EXERCISES
- Q1: Bacteria cannot be seen with the naked eyes, but these can be seen with the help of a microscope. If you have to carry a sample from your home to your biology laboratory to demonstrate the presence of microbes with the help of a microscope, which sample would you carry and why?
- Q1: Bacteria cannot be seen with the naked eyes, but these can be seen with the help of a microscope. If you have to carry a sample from your home to your biology laboratory to demonstrate the presence of microbes with the help of a microscope, which sample would you carry and why?
- Q2: Give examples to prove that microbes release gases during metabolism.
- Q2: Give examples to prove that microbes release gases during metabolism.
- Q3: In which food would you find lactic acid bacteria? Mention some of their useful applications.
- Q3: In which food would you find lactic acid bacteria? Mention some of their useful applications.
- Q4: Name some traditional Indian foods made of wheat, rice and Bengal gram (or their products) which involve use of microbes.
- Q4: Name some traditional Indian foods made of wheat, rice and Bengal gram (or their products) which involve use of microbes.
- Q5: In which way have microbes played a major role in controlling diseases caused by harmful bacteria?
- Q6: Name any two species of fungus, which are used in the production of the antibiotics.
- Q6: Name any two species of fungus, which are used in the production of the antibiotics.
- Q7: What is sewage? In which way can sewage be harmful to us?
- Q7: What is sewage? In which way can sewage be harmful to us?
- Q8: What is the key difference between primary and secondary sewage treatment?
- Q8: What is the key difference between primary and secondary sewage treatment?
- Q9: Do you think microbes can also be used as source of energy? If yes, how?
- Q9: Do you think microbes can also be used as source of energy? If yes, how?
- Q10: Microbes can be used to decrease the use of chemical fertilisers and pesticides. Explain how this can be accomplished.
- Q10: Microbes can be used to decrease the use of chemical fertilisers and pesticides. Explain how this can be accomplished.
- Q11: 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 20mg/L, 8mg/L and 400mg/L, respectively. Which sample of the water is most polluted? Can you assign the correct label to each assuming the river water is relatively clean?
- Q11: 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 (20mg/L), (8mg/L) and (400mg/L), respectively. Which sample of the water is most polluted? Can you assign the correct label to each assuming the river water is relatively clean?
- Q12: Find out the name of the microbes from which Cyclosporin \(A\) (an immunosuppressive drug) and Statins (blood cholesterol lowering agents) are obtained.
- Q12: Find out the name of the microbes from which Cyclosporin (A) (an immunosuppressive drug) and Statins (blood cholesterol lowering agents) are obtained.
- Q13(a): Find out the role of microbes in the following and discuss it with your teacher. (a) Single cell protein (SCP)
- Q13(a): Find out the role of microbes in the following and discuss it with your teacher. (a) Single cell protein (SCP)
- Q13(b): Find out the role of microbes in the following and discuss it with your teacher. (b) Soil
- Q13(b): Find out the role of microbes in the following and discuss it with your teacher. (b) Soil
- Q14: Arrange the following in the decreasing order (most important first) of their importance, for the welfare of human society. Give reasons for your answer. Biogas, Citric acid, Penicillin and Curd
- Q14: Arrange the following in the decreasing order (most important first) of their importance, for the welfare of human society. Give reasons for your answer. Biogas, Citric acid, Penicillin and Curd
- Q15: How do biofertilisers enrich the fertility of the soil?
- Q15: How do biofertilisers enrich the fertility of the soil?
CBSE Solutions for Class 12 Biology Microbes in Human Welfare
Chapters in CBSE - Class 12 Biology
- Reproduction in Organisms
- Human Reproduction
- Reproductive Health
- Principles of Inheritance and Variation
- Molecular Basis of Inheritance
- Evolution
- Human Health and Disease
- Strategies for Enhancement in Food Production
- Biotechnology: Principles and Processes
- Biotechnology and Its Applications
- Organisms and Populations
- Ecosystem
- Biodiversity and Conservation
- Environmental Issues
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