Complete Summary and Solutions for Microbes in Human Welfare – NCERT Class XII Biology, Chapter 8 – Fermentation, Antibiotics, Sewage Treatment, Biogas, Biocontrol, Biofertilizers

Comprehensive summary and explanation of Chapter 8 'Microbes in Human Welfare' from the NCERT Class XII Biology textbook, covering roles of microbes in household and industrial products, production of beverages and antibiotics, sewage treatment processes, biogas generation, microbial biocontrol agents, biofertilizers, and detailed answers to all textbook exercises.

Updated: 7 months ago

Categories: NCERT, Class XII, Biology, Chapter 8, Microbes, Fermentation, Antibiotics, Sewage Treatment, Biogas, Biocontrol, Biofertilizers, Summary, Questions, Answers

Tags: Microbes, Fermentation, Antibiotics, Sewage Treatment, Biogas, Biocontrol, Biofertilizers, Microbiology, NCERT, Class 12, Biology, Chapter 8, Summary, Questions, Answers

Microbes in Human Welfare - Class 12 NCERT Chapter 8 - Ultimate Study Guide, Notes, Questions, Quiz 2025

Full Chapter Summary & Detailed Notes - Microbes in Human Welfare Class 12 NCERT

Overview & Key Concepts

Chapter Goal: Explore beneficial roles of microbes in daily life, industry, environment, and agriculture. Exam Focus: Processes (e.g., fermentation steps, sewage treatment stages), microbes (e.g., LAB, Saccharomyces), applications (e.g., antibiotics, biogas). 2025 Updates: Emphasis on sustainable biotech, Ganga Action Plan integration, Bt crops. Fun Fact: Penicillin saved millions in WWII. Core Idea: Microbes as 'friends' counter pathogens; diverse uses from curd to biofertilisers. Real-World: LAB in probiotics; methanogens in rural energy. Ties: Links to biomolecules (Ch9), ecology (Ch13). Expanded: All subtopics (8.1-8.6) point-wise with principles, steps, examples, and diagram descriptions for visual learning.
Wider Scope: From household fermentation to global sustainability; microbes enable eco-friendly alternatives to chemicals.
Expanded Content: Detailed examples (e.g., cheese varieties), processes (e.g., BOD reduction), benefits (e.g., vitamin B12 in curd).

Fig. 8.1: Bacteria (Description)

Labelled: (a) Rod-shaped (bacilli) magnified 1500x; (b) Spherical (cocci) 1500x; (c) Rod with flagella 50,000x. Visual: Scanning electron micrographs showing shapes and motility structures.

Fig. 8.2: Viruses (Description)

(a) Bacteriophage (T4-like) with head, tail, fibers; (b) Adenovirus (icosahedral, causes respiratory infections); (c) Rod-shaped TMV magnified 100,000-150,000x. Visual: Electron micrographs highlighting viral structures.

Fig. 8.3: Microbial Colonies (Description)

(a) Bacterial colonies on Petri dish (circular, opaque); (b) Fungal colony (fluffy, spreading). Visual: Naked-eye view of growth on nutritive media.

8.1 Microbes in Household Products

Introduction: Microbes enhance food via fermentation; counter Chapter 7's pathogens.
Curd Production: Lactic Acid Bacteria (LAB, e.g., Lactobacillus) convert lactose to lactic acid; coagulates milk proteins; starter curd adds millions of LAB; optimal 30-40°C; increases B12, checks gut pathogens.
Dough Fermentation: Bacteria produce CO2 for puffing (dosa/idli via lactic acid fermentation); bread via Saccharomyces cerevisiae (alcoholic fermentation).
Traditional Foods/Drinks: Toddy (palm sap, S. cerevisiae); fermented fish/soyabean/bamboo shoots; cheese varieties (texture/flavor from microbes).
Cheese Examples: Swiss (Propionibacterium shermanii, CO2 holes); Roquefort (Penicillium roquefortii ripening).
Biotech Relevance: Improves nutrition, preserves food; LAB probiotics for health.

8.2 Microbes in Industrial Products

Overview: Large-scale in fermentors (Fig. 8.4: Vessels with agitators/aeration); sterile conditions for beverages/antibiotics.
8.2.1 Fermented Beverages: Yeasts (S. cerevisiae, brewer's yeast) ferment malted cereals/fruit juices to ethanol (anaerobic glycolysis); wine/beer (no distillation); whisky/brandy/rum (distilled); Fig. 8.5: Plant with distillation towers.
8.2.2 Antibiotics: 'Against life' (pathogens); pro-life for humans; Penicillin (chance discovery by Fleming, 1928; mould Penicillium notatum inhibits Staphylococci); mass-produced by Chain/Florey (Nobel 1945, WWII use); others: Streptomycin (Streptomyces), Tetracycline (S. aureofaciens).
8.2.3 Chemicals, Enzymes, Bioactives: Acids (citric: Aspergillus niger; acetic: Acetobacter aceti; butyric: Clostridium butylicum; lactic: Lactobacillus); Ethanol (S. cerevisiae); Enzymes (lipases in detergents; pectinases/proteases clarify juices; streptokinase clot-buster from Streptococcus); Cyclosporin A (Trichoderma polysporum, immunosuppressant); Statins (Monascus purpureus, cholesterol inhibitor).
Biotech Relevance: Industrial scale reduces costs; genetic engineering enhances yields.

Fig. 8.4: Fermentors (Description)

Cylindrical vessels with stirrers, air inlets, temperature controls. Visual: Large stainless-steel tanks for microbial growth.

Fig. 8.5: Fermentation Plant (Description)

Aerial view: Towers, pipes, distillation units for ethanol production. Visual: Industrial setup with vapor recovery.

8.3 Microbes in Sewage Treatment

Overview: Sewage (municipal wastewater with excreta/organics/pathogens); treated in STPs to reduce pollution before river discharge.
Primary Treatment: Physical (filtration/sedimentation); removes debris/grit; forms primary sludge/effluent.
Secondary (Biological) Treatment: Aeration tanks (Fig. 8.6: Agitation/air pumping); aerobic microbes form flocs (bacteria-fungi mesh) consuming organics; reduces BOD (oxygen for microbial oxidation of organics; high BOD = polluting); effluent to settling tank → activated sludge (inoculum + digester for biogas: CH4/H2S/CO2).
Biogas Use: Inflammable energy source; effluent safe for rivers (Fig. 8.7: Aerial STP view).
Challenges: Urbanization outpaces STPs; Ganga/Yamuna Action Plans build more; microbial treatment superior to man-made.
Biotech Relevance: Recycles water, produces energy; BOD test measures efficiency.

Fig. 8.6: Secondary Treatment (Description)

Aeration tank with mechanical stirrers, air bubbles; flocs settling. Visual: Large rectangular pool with inflow/outflow.

Fig. 8.7: Aerial View of Sewage Plant (Description)

Overview: Tanks, pipes, settling ponds in urban setup. Visual: Satellite-like image showing interconnected units.

8.4 Microbes in Production of Biogas

Overview: Biogas (CH4-rich) from microbial anaerobic digestion of wastes; fuel alternative.
Methanogens: Anaerobic bacteria (e.g., Methanobacterium) on cellulosics produce CH4/CO2/H2; found in rumen/sludge; breakdown cellulose in cattle (humans can't digest).
Biogas Plant: 10-15ft deep tank; dung slurry + bio-wastes; floating cover rises with gas; outlet pipes to homes; spent slurry fertilizer (Fig. 8.8: Gobar gas plant).
Development: IARI/KVIC in India; rural focus (cattle dung abundant); used for cooking/lighting.
Biotech Relevance: Renewable energy; reduces fossil fuels.

Fig. 8.8: Typical Biogas Plant (Description)

Digester tank with gas holder, inlet/outlet pipes, floating cover. Visual: Cross-section showing slurry, gas collection.

8.5 Microbes as Biocontrol Agents

Overview: Biological pest/disease control vs. chemical pesticides (toxic/polluting).
Principles: Organic farming promotes biodiversity; natural predators/parasites maintain pest balance (e.g., ladybird/ dragonfly eat aphids/mosquitoes).
Microbial Agents: Bacillus thuringiensis (Bt: spores/toxin kill caterpillars; Bt-cotton genetically engineered); Trichoderma (fungi antagonize pathogens in roots); Baculoviruses (Nucleopolyhedrovirus: insect-specific, narrow spectrum; no harm to non-targets).
Integrated Pest Management (IPM): Combines biocontrol with minimal chemicals; preserves beneficial insects.
Biotech Relevance: Reduces pesticide use; sustainable agriculture.

8.6 Microbes as Biofertilisers

Overview: Eco-friendly nutrient enrichers vs. chemical fertilisers (polluting); bacteria/fungi/cyanobacteria sources.
Nitrogen Fixers: Rhizobium (symbiotic root nodules in legumes); free-living (Azospirillum/Azotobacter enrich soil N).
Mycorrhiza: Glomus fungi absorb P from soil, pass to plants; benefits: pathogen resistance, drought tolerance; fungi get carbs.
Cyanobacteria: Anabaena/Nostoc/Oscillatoria fix N in paddy; add organics/fertility.
Commercial Use: Available in India; reduces chemical dependence.
Biotech Relevance: Sustainable farming; enhances crop yield naturally.

Summary

Microbes vital for welfare: Fermentation (curd, bread, beverages), antibiotics (penicillin), sewage/BOD reduction, biogas (methanogens), biocontrol (Bt), biofertilisers (Rhizobium).
Interlinks: To health (Ch7), ecology (Ch13); push for organic/sustainable uses.

Why This Guide Stands Out

Microbe-focused: Step-wise processes, visuals, real apps. Free 2025 with mnemonics, case studies (e.g., Ganga Plan) for retention.

Key Themes & Tips

Aspects: Beneficial vs. harmful; fermentation pathways, microbial diversity.
Tip: Memorize microbes (LAB, Bt); draw plant diagrams (biogas/STP).

Exam Case Studies

Penicillin discovery; biogas in rural India; Bt cotton pest resistance.

Project & Group Ideas

Cultivate LAB curd at home, test pH.
Debate: Chemicals vs. biofertilisers impact.
Model biogas plant with balloons.

Key Definitions & Terms - Complete Glossary

All terms from chapter; detailed with examples, relevance. Expanded: 40+ terms grouped by subtopic; added advanced like BOD, methanogens for depth/easy flashcards.

Lactic Acid Bacteria (LAB)

Gram-positive rods ferment lactose to lactic acid. Ex: Lactobacillus in curd. Relevance: Coagulates milk, adds B12.

Fermentation

Anaerobic microbial breakdown of organics to acids/alcohols/gases. Ex: Dough CO2. Relevance: Food processing.

Antibiotics

Microbe-derived chemicals inhibiting pathogen growth. Ex: Penicillin vs. Staphylococci. Relevance: Treat infections.

BOD

Biochemical Oxygen Demand: O2 for microbial oxidation of organics. Ex: High in sewage. Relevance: Pollution measure.

Activated Sludge

Sedimented flocs used as inoculum in aeration. Ex: STP process. Relevance: BOD reduction.

Methanogens

Anaerobic archaea producing CH4 from CO2/H2. Ex: Methanobacterium in rumen. Relevance: Biogas.

Biocontrol

Biological pest suppression. Ex: Bt toxin. Relevance: IPM.

Biofertiliser

Microbe enriching soil nutrients. Ex: Rhizobium N-fixer. Relevance: Organic farming.

Mycorrhiza

Fungal-plant symbiosis for P uptake. Ex: Glomus. Relevance: Drought tolerance.

Cyanobacteria

Photosynthetic N-fixers. Ex: Anabaena in paddy. Relevance: Soil fertility.

Flocs

Bacteria-fungi mesh consuming organics. Ex: Aeration tanks. Relevance: Sewage treatment.

Streptokinase

Clot-buster enzyme. Ex: Heart attack therapy. Relevance: Bioactive molecule.

Cyclosporin A

Immunosuppressant. Ex: Organ transplants. Relevance: Fungal product.

Statins

Cholesterol inhibitors. Ex: Monascus. Relevance: Cardiovascular health.

Bt Toxin

Insecticidal protein. Ex: Caterpillar gut lysis. Relevance: Transgenic crops.

Nucleopolyhedrovirus

Viral insecticide. Ex: Narrow spectrum. Relevance: IPM.

Rhizobium

Symbiotic N-fixer. Ex: Legume nodules. Relevance: Nitrogen cycle.

Azotobacter

Free-living N-fixer. Ex: Soil enrichment. Relevance: Non-legumes.

Glomus

Mycorrhizal fungus. Ex: P absorption. Relevance: Root health.

Anabaena

Cyanobacterial N-fixer. Ex: Paddy fields. Relevance: Organic matter.

Tip: Group by subtopic; examples for recall. Depth: Principles tie to metabolism/ecology. Errors: Confuse LAB vs. methanogens. Historical: Fleming/Penicillin. Interlinks: Ch7 diseases. Advanced: Bt genes. Real-Life: Curd probiotics. Graphs: BOD curves. Coherent: Household → Industry → Environment → Agriculture. For easy learning: Flashcard per term with example/app.

60+ Questions & Answers - NCERT Based (Class 12) - From Exercises & Variations

Based on chapter + expansions. Part A: 10 (1 mark, one line), Part B: 10 (4 marks, five lines), Part C: 10 (6 marks, eight lines). Answers point-wise in black text. Easy: Structured for marks.

Part A: 1 Mark Questions (10 Qs - Short)

1. Name the bacteria used in curd production.

1 Mark Answer: Lactic Acid Bacteria (LAB) like Lactobacillus.

2. What gas causes dough puffing in idli/dosa?

1 Mark Answer: Carbon dioxide (CO2) from bacterial fermentation.

3. Who discovered penicillin and how?

1 Mark Answer: Alexander Fleming via mould inhibiting Staphylococci growth.

4. What does BOD measure in sewage?

1 Mark Answer: Oxygen required by microbes to oxidise organic matter.

5. Name the methanogenic bacterium in biogas.

1 Mark Answer: Methanobacterium.

6. What is Bt in biocontrol?

1 Mark Answer: Bacillus thuringiensis toxin killing caterpillars.

7. Name a symbiotic N-fixer in legumes.

1 Mark Answer: Rhizobium.

8. What is the role of Trichoderma?

1 Mark Answer: Biocontrol of plant pathogens.

9. What produces holes in Swiss cheese?

1 Mark Answer: CO2 from Propionibacterium shermanii.

10. Name a cyanobacterium biofertiliser.

1 Mark Answer: Anabaena.

Part B: 4 Marks Questions (10 Qs - Medium, Exactly 5 Lines Each)

1. Explain curd formation by LAB.

4 Marks Answer:

LAB (Lactobacillus) ferments lactose to lactic acid.
Acid coagulates and partially digests milk proteins.
Starter curd inoculum multiplies at 30-40°C.
Increases vitamin B12; checks gut pathogens.
Nutritional enhancement for daily use.

2. Describe alcoholic fermentation in beverages.

4 Marks Answer:

S. cerevisiae ferments sugars to ethanol + CO2.
Malted cereals/fruit juices as substrates.
Wine/beer: No distillation; whisky/rum: Distilled.
Anaerobic glycolysis pathway.
Industrial scale in fermentors.

3. How was penicillin discovered?

4 Marks Answer:

Fleming observed mould (P. notatum) inhibiting Staphylococci.
Chemical from mould named penicillin.
Chain/Florey mass-produced for WWII.
Nobel 1945 for discovery.
Treats deadly diseases like plague.

4. Outline primary and secondary sewage treatment.

4 Marks Answer:

Primary: Physical filtration/sedimentation removes debris/grit.
Forms primary sludge; effluent to secondary.
Secondary: Biological; aeration tanks with flocs reduce BOD.
Activated sludge digester produces biogas.
Efluent safe for rivers.

5. Explain biogas production process.

4 Marks Answer:

Methanogens anaerobically digest cellulosics to CH4.
Dung slurry in digester tank; floating cover collects gas.
Spent slurry as fertiliser.
Rumen bacteria aid cattle cellulose breakdown.
Rural energy via IARI/KVIC tech.

6. Describe Bt as biocontrol agent.

4 Marks Answer:

B. thuringiensis spores/toxin ingested by larvae.
Toxin released in gut, lyses cells.
Specific to caterpillars; safe for others.
Genetic engineering: Bt toxin genes in plants (Bt-cotton).
Reduces pesticide use.

7. How do biofertilisers work?

4 Marks Answer:

Enrich soil nutrients naturally.
Rhizobium fixes N in legume nodules.
Azotobacter free-living N-fixer.
Mycorrhiza (Glomus) enhances P uptake.
Cyanobacteria add N/organics in fields.

8. Role of microbes in cheese production.

4 Marks Answer:

Fermentation imparts texture/flavor.
Swiss: P. shermanii produces CO2 holes.
Roquefort: P. roquefortii ripening fungus.
Traditional oldest microbe use.
Varieties from specific strains.

9. What is the significance of flocs in STP?

4 Marks Answer:

Masses of bacteria + fungal filaments.
Form mesh-like structures in aeration.
Consume organics, reduce BOD.
Sediment as activated sludge.
Used as inoculum/digester.

10. Explain cyclosporin A production.

4 Marks Answer:

Bioactive from fungus T. polysporum.
Immunosuppressive for transplants.
Inhibits T-cell activation.
Commercial via fermentation.
Key in organ rejection prevention.

Part C: 6 Marks Questions (10 Qs - Long, Exactly 8 Lines Each)

1. Describe sewage treatment stages with BOD role.

6 Marks Answer:

Primary: Sequential filtration removes floating debris; sedimentation grit/pebbles → primary sludge.
Efluent to secondary: Aeration tanks agitate/air pump for floc growth.
Flocs (bacteria-fungi) consume organics; BOD (O2 for oxidation) reduces from 300 to 100 mg/L.
High BOD = high pollution potential.
Settling: Activated sludge (inoculum 10%); rest to anaerobic digester → biogas (CH4).
Efluent discharged; process recycles water naturally.
Challenges: Urban sewage overload; Action Plans build STPs.
Microbes superior; practiced globally over century.

2. Explain industrial antibiotic production with penicillin example.

6 Marks Answer:

Microbes in large fermentors under sterile conditions.
Penicillin: P. notatum mould produces; Fleming 1928 chance on unwashed plate.
Mould secreted chemical inhibiting Staphylococci around it.
Chain/Florey purified/mass-produced for WWII soldiers.
Nobel 1945; treats plague/whooping cough/diphtheria/leprosy.
Others: Streptomycin (S. griseus), Chloramphenicol (S. venezuelae).
Mechanism: Inhibit cell wall synthesis in bacteria.
Relevance: Revolutionised medicine; overuse leads resistance.

3. Detail biogas plant working and methanogens.

6 Marks Answer:

Concrete tank (10-15ft) collects bio-wastes/dung slurry.
Anaerobic methanogens (Methanobacterium) digest cellulose to CH4/CO2/H2.
Floating cover rises with gas; pipe outlet to homes.
Spent slurry fertiliser via another outlet.
Rumen methanogens aid cattle; gobar gas from dung.
Developed by IARI/KVIC; rural cooking/lighting.
Biogas ~60% CH4; inflammable energy.
Sustainable; reduces waste, fossil fuel dependence.

4. Discuss biocontrol with Bt and Trichoderma examples.

6 Marks Answer:

Alternatives to toxic pesticides; promotes biodiversity.
Bt: B. thuringiensis spores/toxin; larvae ingest, gut toxin lyses cells.
Specific to lepidopterans; Bt-cotton via gene insertion (Ch10).
Trichoderma: Free-living root fungi; antagonise pathogens via competition.
Baculoviruses: Nucleopolyhedrovirus attacks insects; narrow spectrum, safe for non-targets.
IPM: Integrates with predators (ladybird aphids).
Benefits: Reduces chemicals; preserves ecosystem.
Apps: Brassicas/fruit trees; ecologically sensitive areas.

5. Explain biofertilisers with Rhizobium and mycorrhiza.

6 Marks Answer:

Reduce chemical pollution; enrich soil N/P.
Rhizobium: Symbiotic in legume nodules; fixes atmospheric N to ammonia.
Azotobacter: Free-living aerobic N-fixer in soil.
Mycorrhiza (Glomus): Fungal hyphae absorb P, pass to plant; gets carbs.
Benefits: Root resistance, salinity/drought tolerance, growth boost.
Cyanobacteria (Anabaena): Paddy N-fixer; adds organics.
Commercial: Sachets for fields; India widespread.
Sustainable: Enhances yield, cuts fertiliser costs.

6. Describe household microbial products with examples.

6 Marks Answer:

Curd: LAB ferments milk; acid coagulates, adds B12.
Dough: Bacteria CO2 for dosa/idli; yeast for bread.
Toddy: Palm sap by S. cerevisiae.
Fermented foods: Fish/soyabean/bamboo shoots.
Cheese: Swiss (P. shermanii CO2); Roquefort (P. roquefortii flavor).
Traditional Indian: Dosa/idli from rice/black gram.
Benefits: Nutrition, preservation, probiotics.
Everyday use; counters pathogens.

7. Role of microbes in industrial chemicals/enzymes.

6 Marks Answer:

Organic acids: Citric (A. niger), Acetic (A. aceti).
Enzymes: Lipases (detergents oily stains); Pectinases (juice clarity).
Streptokinase: Streptococcus clot-buster for heart attack.
Cyclosporin A: T. polysporum immunosuppressant transplants.
Statins: M. purpureus inhibits cholesterol synthesis.
Fermentor scale-up; genetic mods enhance.
Apps: Food/pharma; eco-friendly.
Reduces synthetic chemical use.

8. Significance of antibiotics in human welfare.

6 Marks Answer:

20th C discovery; treat deadly infections.
Penicillin: First, WWII saviour; vs. Gram+.
Others: Tetracycline broad-spectrum; Streptomycin TB.
Mechanism: Inhibit cell wall/protein synthesis.
Controlled plague/whooping cough/diphtheria/leprosy.
Challenges: Resistance; overuse caution.
Microbe-derived; industrial fermentors.
Pro-life for humans; against pathogens.

9. How do cyanobacterial biofertilisers benefit soil?

6 Marks Answer:

Autotrophic N-fixers (heterocysts).
Anabaena/Nostoc/Oscillatoria in aquatic/terrestrial.
Fix atmospheric N to ammonia.
Add organic matter/fertility in paddy.
Blue-green algae; symbiotic with Azolla.
Reduce chemical N needs.
Enhance soil structure/water retention.
Commercial packets for farmers.

10. Discuss organic farming via biocontrol.

6 Marks Answer:

Biodiversity maintains pest balance.
Natural predators: Ladybird (aphids), Dragonfly (mosquitoes).
Microbial: Bt sachet spray on plants.
Trichoderma root competition vs. pathogens.
Baculovirus: Species-specific, no non-target harm.
IPM: Holistic; avoids eradication.
Benefits: Reduces toxins; sustainable yields.
Study life cycles/habitats for targeted control.

Tip: Diagrams for processes; practice steps. Additional 30 Qs: Variations on Ganga Plan, cheese types.

Key Concepts - In-Depth Exploration

Core ideas with examples, pitfalls, interlinks. Expanded: All 8.1-8.6 with steps/examples/pitfalls for easy learning. Depth: Pathways (e.g., lactic fermentation), calculations (e.g., BOD reduction).

Household Fermentation (8.1)

Steps: 1. Inoculate milk/dough with starter, 2. Incubate 30-40°C, 3. Acid/CO2 forms product. Ex: Curd LAB. Pitfall: Over-ferment sour. Interlink: Metabolism Ch9. Depth: Lactic acid pH drop 6 to 4.

Industrial Beverages (8.2.1)

Steps: 1. Malt/juice + yeast, 2. Ferment anaerobic, 3. Distill if needed. Ex: Beer ethanol 5%. Pitfall: Contamination off-flavor. Interlink: Enzymes. Depth: Glycolysis yield 2 ATP.

Antibiotics (8.2.2)

Steps: 1. Mould growth inhibits bacteria, 2. Extract/purify. Ex: Penicillin WWII. Pitfall: Resistance. Interlink: Ch7 diseases. Depth: Beta-lactam ring target.

Sewage Treatment (8.3)

Steps: 1. Primary physical, 2. Secondary flocs BOD drop 70%, 3. Digester biogas. Ex: STP effluent. Pitfall: Overload high BOD. Interlink: Ecology. Depth: BOD test 5 days 20°C.

Biogas (8.4)

Steps: 1. Slurry anaerobic, 2. Methanogens CH4, 3. Collect/use. Ex: Gobar 200L/cow/day. Pitfall: O2 leak. Interlink: Energy. Depth: 60% CH4 calorific 5000 kcal/m3.

Biocontrol (8.5)

Steps: 1. Spray Bt spores, 2. Larvae ingest/toxin activate. Ex: Bt-cotton bollworm. Pitfall: UV degrade. Interlink: Genetics Ch10. Depth: Cry toxin pores in gut.

Biofertilisers (8.6)

Steps: 1. Inoculate seeds Rhizobium, 2. Nodules form/fix. Ex: Soybean yield +20%. Pitfall: pH sensitivity. Interlink: Plants Ch2. Depth: Nitrogenase enzyme O2-sensitive.

Advanced: Fermentation equations, BOD calcs. Pitfalls: Contam in cultures. Interlinks: Ch13 ecosystem. Real: COVID probiotics. Depth: 6 subtopics details. Examples: Toddy. Graphs: BOD decline. Errors: Confuse biogas/sewage. Tips: Steps for processes; compare tables (chemical vs bio).

Term/Process	Description	Example	Usage
LAB	Lactic acid fermenters	Curd Lactobacillus	Food coagulation
Fermentation	Anaerobic catabolism	Dough CO2	Preservation
Antibiotics	Pathogen inhibitors	Penicillin	Infection control
BOD	O2 for organic oxidation	Sewage 300 mg/L	Pollution index
Flocs	Microbial mesh	Aeration tank	BOD reduction
Methanogens	CH4 producers	Methanobacterium	Biogas
Biocontrol	Pest biological suppression	Bt toxin	IPM
Biofertiliser	Nutrient enricher	Rhizobium	Organic farming
Mycorrhiza	Fungal symbiosis	Glomus P uptake	Root health
Cyanobacteria	N-fixing algae	Anabaena	Paddy fertility
Propionibacterium	CO2 producer	Swiss cheese	Texture
Streptokinase	Clot dissolver	Heart attack	Therapy
Cyclosporin A	Immunosuppressant	Transplants	Rejection prevent
Statins	Cholesterol blocker	Monascus	Cardio health
Cry Toxin	Bt protein	Caterpillar lysis	Pest control
Nucleopolyhedrovirus	Insect virus	Arthropod pathogen	Narrow IPM
Azotobacter	Free N-fixer	Soil bacteria	Non-legume
Ethidium Bromide	No, but gel stain	DNA vis	Electrophoresis

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10 Qs · ~10 min

#26

Class 12 Psychology — Therapeutic Approaches (Practice Quiz)

10 Qs · ~10 min

#27

Class 12 Psychology — Psychological Disorders (Practice Quiz)

10 Qs · ~10 min

#28

Class 12 Psychology — Meeting Life Challenges (Practice Quiz)

10 Qs · ~10 min

#29

Class 12 Psychology — Self and Personality (Practice Quiz)

10 Qs · ~10 min

#30

Class 12 Psychology — Variations in Psychological Attributes (Practice Quiz)

10 Qs · ~10 min

#31

Class 12 Sociology — Social Movements (Practice Quiz)

10 Qs · ~10 min

#32

Class 12 Sociology — Mass Media and Communications (Practice Quiz)

10 Qs · ~10 min

#33

Class 12 Sociology — Globalisation and Social Change (Practice Quiz)

10 Qs · ~10 min

#34

Class 12 Sociology — Change and Development in Industrial Society (Practice Quiz)

10 Qs · ~10 min

#35

Class 12 Sociology — Change and Development in Rural Society (Practice Quiz)

10 Qs · ~10 min

#36

Class 12 Sociology — The Constitution and Social Change (Practice Quiz)

10 Qs · ~10 min

#37

Class 12 Sociology — Cultural Change (Practice Quiz)

10 Qs · ~10 min

#38

Class 12 Sociology — Structural Change (Practice Quiz)

10 Qs · ~10 min

#39

Class 12 Sociology — The Challenges of Cultural Diversity (Practice Quiz)

10 Qs · ~10 min

#40

Class 12 Sociology — Patterns of Social Inequality and Exclusion (Practice Quiz)

10 Qs · ~10 min

#41

Class 12 Sociology — The Market as a Social Institution (Practice Quiz)

10 Qs · ~10 min

#42

Class 12 Sociology — Social Institutions: Continuity and Change (Practice Quiz)

10 Qs · ~10 min

#43

Class 12 Sociology — The Demographic Structure of the Indian Society (Practice Quiz)

10 Qs · ~10 min

#44

Class 12 Sociology — Introducing Indian Society (Practice Quiz)

10 Qs · ~10 min

#45

Class 12 Political Science — Recent Developments in Indian Politics (Practice Quiz)

10 Qs · ~10 min

#46

Class 12 Political Science — Regional Aspirations (Practice Quiz)

10 Qs · ~10 min

#47

Class 12 Political Science — The Crisis of Democratic Order (Practice Quiz)

10 Qs · ~10 min

#48

Class 12 Political Science — Challenges to and Restoration of the Congress System (Practice Quiz)

10 Qs · ~10 min

#49

Class 12 Political Science — India's External Relations (Practice Quiz)

10 Qs · ~10 min

#50

Class 12 Political Science — Politics of Planned Development (Practice Quiz)

10 Qs · ~10 min

#51

Class 12 Political Science — Era of One-party Dominance (Practice Quiz)

10 Qs · ~10 min

#52

Class 12 Political Science — Challenges of Nation Building (Practice Quiz)

10 Qs · ~10 min

#53

Class 12 Political Science — Environment and Natural Resources (Practice Quiz)

10 Qs · ~10 min

#54

Class 12 Political Science — Security in the Contemporary World (Practice Quiz)

10 Qs · ~10 min

#55

Class 12 Political Science — International Organisations (Practice Quiz)

10 Qs · ~10 min

#56

Class 12 Political Science — Contemporary South Asia (Practice Quiz)

10 Qs · ~10 min

#57

Class 12 Political Science — Contemporary Centres of Power (Practice Quiz)

10 Qs · ~10 min

#58

Class 12 Political Science — The End of Bipolarity (Practice Quiz)

10 Qs · ~10 min

#59

Class 12 Geography — Geographical Perspective on Selected Issues and Problems (Practice Quiz)

10 Qs · ~10 min

#60

Class 12 Geography — Planning and Sustainable Development in the Indian Context (Practice Quiz)

10 Qs · ~10 min

#61

Class 12 Geography — Mineral and Energy Resources (Practice Quiz)

10 Qs · ~10 min

#62

Class 12 Geography — Water Resources (Practice Quiz)

10 Qs · ~10 min

#63

Class 12 Geography — Land Resources and Agriculture (Practice Quiz)

10 Qs · ~10 min

#64

Class 12 Geography — Human Settlements (Practice Quiz)

10 Qs · ~10 min

#65

Class 12 Geography — Population: Distribution, Density, Growth and Composition (Practice Quiz)

10 Qs · ~10 min

#66

Class 12 Geography — International Trade (India) (Practice Quiz)

10 Qs · ~10 min

#67

Class 12 Geography — Transport and Communication (India) (Practice Quiz)

10 Qs · ~10 min

#68

Class 12 Geography — Tertiary and Quaternary Activities (Practice Quiz)

10 Qs · ~10 min

#69

Class 12 Geography — Secondary Activities (Practice Quiz)

10 Qs · ~10 min

#70

Class 12 Geography — Primary Activities (Practice Quiz)

10 Qs · ~10 min

#71

Class 12 Geography — Human Development (Practice Quiz)

10 Qs · ~10 min

#72

Class 12 Geography — The World Population: Distribution, Density and Growth (Practice Quiz)

10 Qs · ~10 min

#73

Class 12 Geography — Human Geography: Nature and Scope (Practice Quiz)

10 Qs · ~10 min

#74

Class 12 History — Framing the Constitution — The Beginning of a New Era (Practice Quiz)

10 Qs · ~10 min

#75

Class 12 History — Mahatma Gandhi and the Nationalist Movement — Civil Disobedience and Beyond (Practice Quiz)

10 Qs · ~10 min

#76

Class 12 History — Rebels and the Raj — The Revolt of 1857 and its Representations (Practice Quiz)

10 Qs · ~10 min

#77

Class 12 History — Colonialism and the Countryside — Exploring Official Archives (Practice Quiz)

10 Qs · ~10 min

#78

Class 12 History — Peasants, Zamindars and the State — Agrarian Society and the Mughal Empire (c. sixteenth-seventeenth centuries) (Practice Quiz)

10 Qs · ~10 min

#79

Class 12 History — An Imperial Capital: Vijayanagara (c. fourteenth to sixteenth century) (Practice Quiz)

10 Qs · ~10 min

#80

Class 12 History — Bhakti-Sufi Traditions — Changes in Religious Beliefs and Devotional Texts (c. eighth to eighteenth century) (Practice Quiz)

10 Qs · ~10 min

#81

Class 12 History — Through the Eyes of Travellers — Perceptions of Society (c. tenth to seventeenth century) (Practice Quiz)

10 Qs · ~10 min

#82

Class 12 History — Thinkers, Beliefs and Buildings — Cultural Developments (c. 600 BCE-600 CE) (Practice Quiz)

10 Qs · ~10 min

#83

Class 12 History — Kinship, Caste and Class — Early Societies (c. 600 BCE-600 CE) (Practice Quiz)

10 Qs · ~10 min

#84

Class 12 History — Kings, Farmers and Towns — Early States and Economies (c. 600 BCE-600 CE) (Practice Quiz)

10 Qs · ~10 min

#85

Class 12 History — Bricks, Beads and Bones — The Harappan Civilisation (Practice Quiz)

10 Qs · ~10 min

#86

Class 12 Economics — Open Economy Macroeconomics (Practice Quiz)

10 Qs · ~10 min

#87

Class 12 Economics — Government Budget and the Economy (Practice Quiz)

10 Qs · ~10 min

#88

Class 12 Economics — Determination of Income and Employment (Practice Quiz)

10 Qs · ~10 min

#89

Class 12 Economics — Money and Banking (Practice Quiz)

10 Qs · ~10 min

#90

Class 12 Economics — National Income Accounting (Practice Quiz)

10 Qs · ~10 min

#91

Class 12 Economics — Market Equilibrium (Practice Quiz)

10 Qs · ~10 min

#92

Class 12 Economics — The Theory of the Firm under Perfect Competition (Practice Quiz)

10 Qs · ~10 min

#93

Class 12 Economics — Production and Costs (Practice Quiz)

10 Qs · ~10 min

#94

Class 12 Economics — Theory of Consumer Behaviour (Practice Quiz)

10 Qs · ~10 min

#95

Class 12 Economics — Introduction (Practice Quiz)

10 Qs · ~10 min

#96

Class 12 Business Studies — Consumer Protection (Practice Quiz)

10 Qs · ~10 min

#97

Class 12 Business Studies — Marketing (Practice Quiz)

10 Qs · ~10 min

#98

Class 12 Business Studies — Financial Management (Practice Quiz)

10 Qs · ~10 min

#99

Class 12 Business Studies — Controlling (Practice Quiz)

10 Qs · ~10 min

#100

Class 12 Business Studies — Directing (Practice Quiz)

10 Qs · ~10 min

#101

Class 12 Business Studies — Staffing (Practice Quiz)

10 Qs · ~10 min

#102

Class 12 Business Studies — Organising (Practice Quiz)

10 Qs · ~10 min

#103

Class 12 Business Studies — Planning (Practice Quiz)

10 Qs · ~10 min

#104

Class 12 Business Studies — Business Environment (Practice Quiz)

10 Qs · ~10 min

#105

Class 12 Business Studies — Nature and Significance of Management (Practice Quiz)

10 Qs · ~10 min

#106

Class 12 Accountancy — Cash Flow Statement (Practice Quiz)

10 Qs · ~10 min

#107

Class 12 Accountancy — Accounting Ratios (Practice Quiz)

10 Qs · ~10 min

#108

Class 12 Accountancy — Analysis of Financial Statements (Practice Quiz)

10 Qs · ~10 min

#109

Class 12 Accountancy — Financial Statements of a Company (Practice Quiz)

10 Qs · ~10 min

#110

Class 12 Accountancy — Issue and Redemption of Debentures (Practice Quiz)

10 Qs · ~10 min

#111

Class 12 Accountancy — Accounting for Share Capital (Practice Quiz)

10 Qs · ~10 min

#112

Class 12 Accountancy — Dissolution of Partnership Firm (Practice Quiz)

10 Qs · ~10 min

#113

Class 12 Accountancy — Reconstitution of a Partnership Firm – Retirement/Death of a Partner (Practice Quiz)

10 Qs · ~10 min

#114

Class 12 Accountancy — Reconstitution of a Partnership Firm – Admission of a Partner (Practice Quiz)

10 Qs · ~10 min

#115

Class 12 Accountancy — Accounting for Partnership: Basic Concepts (Practice Quiz)

10 Qs · ~10 min

#116

Class 12 Maths — Probability (Practice Quiz)

10 Qs · ~10 min

#117

Class 12 Maths — Linear Programming (Practice Quiz)

10 Qs · ~10 min

#118

Class 12 Maths — Three Dimensional Geometry (Practice Quiz)

10 Qs · ~10 min

#119

Class 12 Maths — Vector Algebra (Practice Quiz)

10 Qs · ~10 min

#120

Class 12 Maths — Differential Equations (Practice Quiz)

10 Qs · ~10 min

#121

Class 12 Maths — Application of Integrals (Practice Quiz)

10 Qs · ~10 min

#122

Class 12 Maths — Integrals (Practice Quiz)

10 Qs · ~10 min

#123

Class 12 Maths — Application of Derivatives (Practice Quiz)

10 Qs · ~10 min

#124

Class 12 Maths — Continuity and Differentiability (Practice Quiz)

10 Qs · ~10 min

#125

Class 12 Maths — Determinants (Practice Quiz)

10 Qs · ~10 min

#126

Class 12 Maths — Matrices (Practice Quiz)

10 Qs · ~10 min

#127

Class 12 Maths — Inverse Trigonometric Functions (Practice Quiz)

10 Qs · ~10 min

#128

Class 12 Maths — Relations and Functions (Practice Quiz)

10 Qs · ~10 min

#129

Class 12 Biology — Biodiversity and its Conservation (Practice Quiz)

10 Qs · ~10 min

#130

Class 12 Biology — Ecosystem (Practice Quiz)

10 Qs · ~10 min

#131

Class 12 Biology — Organisms and Populations (Practice Quiz)

10 Qs · ~10 min

#132

Class 12 Biology — Biotechnology and its Applications (Practice Quiz)

10 Qs · ~10 min

#133

Class 12 Biology — Biotechnology: Principles and Processes (Practice Quiz)

10 Qs · ~10 min

#134

Class 12 Biology — Microbes in Human Welfare (Practice Quiz)

10 Qs · ~10 min

#135

Class 12 Biology — Human Health and Disease (Practice Quiz)

10 Qs · ~10 min

#136

Class 12 Biology — Evolution (Practice Quiz)

10 Qs · ~10 min

#137

Class 12 Biology — Molecular Basis of Inheritance (Practice Quiz)

10 Qs · ~10 min

#138

Class 12 Biology — Principles of Inheritance and Variation (Practice Quiz)

10 Qs · ~10 min

#139

Class 12 Biology — Reproductive Health (Practice Quiz)

10 Qs · ~10 min

#140

Class 12 Biology — Human Reproduction (Practice Quiz)

10 Qs · ~10 min

#141

Class 12 Biology — Sexual Reproduction in Flowering Plants (Practice Quiz)

10 Qs · ~10 min

#142

Class 12 Chemistry — Biomolecules (Practice Quiz)

10 Qs · ~10 min

#143

Class 12 Chemistry — Amines (Practice Quiz)

10 Qs · ~10 min

#144

Class 12 Chemistry — Aldehydes, Ketones and Carboxylic Acids (Practice Quiz)

10 Qs · ~10 min

#145

Class 12 Chemistry — Alcohols, Phenols and Ethers (Practice Quiz)

10 Qs · ~10 min

#146

Class 12 Chemistry — Haloalkanes and Haloarenes (Practice Quiz)

10 Qs · ~10 min

#147

Class 12 Chemistry — Coordination Compounds (Practice Quiz)

10 Qs · ~10 min

#148

Class 12 Chemistry — The d- and f-Block Elements (Practice Quiz)

10 Qs · ~10 min

#149

Class 12 Chemistry — Chemical Kinetics (Practice Quiz)

10 Qs · ~10 min

#150

Class 12 Chemistry — Electrochemistry (Practice Quiz)

10 Qs · ~10 min

#151

Class 12 Chemistry — Solutions (Practice Quiz)

10 Qs · ~10 min

#152

Class 12 Physics — Semiconductor Electronics: Materials, Devices and Simple Circuits (Practice Quiz)

10 Qs · ~10 min

#153

Class 12 Physics — Nuclei (Practice Quiz)

10 Qs · ~10 min

#154

Class 12 Physics — Atoms (Practice Quiz)

10 Qs · ~10 min

#155

Class 12 Physics — Dual Nature of Radiation and Matter (Practice Quiz)

10 Qs · ~10 min

#156

Class 12 Physics — Wave Optics (Practice Quiz)

10 Qs · ~10 min

#157

Class 12 Physics — Ray Optics and Optical Instruments (Practice Quiz)

10 Qs · ~10 min

#158

Class 12 Physics — Electromagnetic Waves (Practice Quiz)

10 Qs · ~10 min

#159

Class 12 Physics — Alternating Current (Practice Quiz)

10 Qs · ~10 min

#160

Class 12 Physics — Electromagnetic Induction (Practice Quiz)

10 Qs · ~10 min

#161

Class 12 Physics — Magnetism and Matter (Practice Quiz)

10 Qs · ~10 min

#162

Class 12 Physics — Moving Charges and Magnetism (Practice Quiz)

10 Qs · ~10 min

#163

Class 12 Physics — Electrostatic Potential and Capacitance (Practice Quiz)

10 Qs · ~10 min

#164

Class 12 Physics — Electric Charges and Fields (Practice Quiz)

10 Qs · ~10 min

#165

Class 12 Business Studies — Principles of Management (Practice Quiz)

10 Qs · ~10 min

#166

CBSE Class 12 — Genetics and Evolution (Practice Quiz)

10 Qs · ~10 min

#167

CBSE Class 12 — Matrices and Determinants (Practice Quiz)

10 Qs · ~10 min

#168

CBSE Class 12 — Solutions and Colligative Properties (Practice Quiz)

10 Qs · ~10 min

#169

Class 12 Physics — Current Electricity (Practice Quiz)

10 Qs · ~10 min

#170

CBSE Class 12 — Electrostatics and Electric Field (Practice Quiz)

10 Qs · ~10 min

#171

Humanities Subjects Practice Quiz | CBSE Class 12 Board Examination

10 Qs · ~10 min

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