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Q3:
In which food would you find lactic acid bacteria? Mention some of their useful applications.
Solution :
Identification of Lactic Acid Bacteria (LAB) Habitat
Lactic Acid Bacteria (LAB), predominantly species of the genus Lactobacillus, are ubiquitously found in milk and dairy-based substrates. These bacteria are primarily responsible for the transformation of milk into curd and yogurt [Biochemical transformation via fermentation].
Step 1: Mechanism of Action
During the process of fermentation, LAB act on lactose sugar ($C_{12}H_{22}O_{11}$) present in milk. The metabolic pathway involves the following chemical reaction:
$C_{12}H_{22}O_{11} + H_2O \rightarrow 4C_3H_6O_3 \text{ (Lactic Acid)}$
This process results in the coagulation and partial digestion of milk proteins, specifically casein, which leads to the formation of curd.
Step 2: Useful Applications of LAB
The applications of LAB extend beyond simple coagulation, playing critical roles in nutrition and intestinal health:
- Nutritional Enhancement: LAB significantly increase the nutritional value of curd by augmenting the concentration of Vitamin $B_{12}$ [Nutritional fortification].
- Probiotic Properties: In the human gastrointestinal tract, LAB play a beneficial role by checking the proliferation of disease-causing pathogens [Competitive inhibition of pathogenic growth].
- Digestive Aid: The pre-digestion of milk proteins by LAB makes curd easier to digest for individuals with mild lactose sensitivity.
Visual Representation of Fermentation Process
Summary Comparison of Milk vs. Curd
| Parameter | Milk | Curd (Post-LAB action) |
|---|---|---|
| Primary Sugar | Lactose | Lactic Acid |
| Vitamin $B_{12}$ Content | Baseline | Enhanced |
| Protein State | Soluble Casein | Coagulated/Partially Digested |
Final Solution: Lactic Acid Bacteria (LAB) are primarily found in milk and dairy products. Their useful applications include the production of curd from milk, the significant enrichment of nutritional content (specifically Vitamin $B_{12}$), and the enhancement of host immunity by suppressing pathogenic microorganisms in the human digestive system.
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.
- 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?
- 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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