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Microbes in Human Welfare

Microbes in Human WelfareNEET Zoology · Class 12 · NCERT Chapter 8

3 interactive concept widgets for Microbes in Human Welfare. Drag any slider, change any number, and watch the formula and the answer update live. Built so you understand how each NEET problem actually works, not just the final number.

Microbes and their products

Explore which microbe gives which product, across household items, fermented beverages, antibiotics, chemicals and bioactive molecules.

Microbes in human welfare

Microbes and their products: from curd to statins

Select a product category to explore the microbe responsible, the product it makes and the key NEET fact. Covers household products, fermented beverages, antibiotics, industrial chemicals and bioactive molecules.

Household Products
Fermented Beverages
Antibiotics
Chemicals and Enzymes
Bioactive Molecules
Curd
Leavened bread, idli, dosa
Swiss cheese (large holes)
Roquefort cheese (blue veins, ...

Microbe

Lactobacillus (LAB)

Product

Curd

NEET fact

LAB converts lactose to lactic acid, which coagulates milk. LAB also produce vitamin B12. A small amount of old curd added to fresh milk acts as a starter (inoculum).

Microbe

Product

Lactobacillus (LAB)

Curd

Saccharomyces cerevisiae (yeast)

Leavened bread, idli, dosa

Propionibacterium sharmanii

Swiss cheese (large holes)

Penicillium roqueforti

Roquefort cheese (blue veins, tangy)

Try this

  • Which Penicillium species makes the antibiotic and which makes the blue cheese? They are different species.
  • Compare the two Trichoderma roles: one produces cyclosporin A, another is used as a biocontrol agent. They are different strains.
  • Can you list all the acids produced by microbes in the chemicals category and match each to its producing organism?

Sewage treatment walk-through

Step through primary and secondary sewage treatment and anaerobic digestion, and watch the BOD fall.

Sewage treatment

Sewage treatment: three stages step by step

Click each stage to see the type of process, what goes in, what comes out, how BOD changes and the NEET fact about it. Covers primary (physical), secondary/biological (flocs, aeration, activated sludge) and anaerobic digestion (biogas from methanogens).

1. Primary Treatment

2. Secondary Treatment

3. Anaerobic Sludge Digestion

Input

Raw sewage (high BOD, high suspended solids)

Physical

Output

Clarified liquid (primary effluent) with reduced suspended solids. BOD is reduced only partially.

BOD reduced by about 20 to 30%

Primary Treatment

Type

Physical (mechanical)

Where

Settling tanks and screens

What happens

Sewage passes through bar screens that remove large floating objects (rags, plastic, debris). Then grit and sand settle out. Finally the sewage sits in a large settling tank where suspended solids (sludge) settle to the bottom. The floating scum (oil and grease) is skimmed off. This is entirely a physical process, no biology.

NEET fact

Primary treatment is purely physical. It removes large solids and grit. It does NOT reduce BOD significantly.

Try this

  • Which stage reduces BOD the most? Compare the BOD change labels at each step.
  • What are flocs and in which stage do they form? What organisms make them?
  • What happens to the activated sludge after secondary treatment? Where does it go and what does it produce?

Biocontrol and biofertilisers

Explore microbes and organisms used as biocontrol agents and biofertilisers, with what each one controls or enriches.

Biocontrol and biofertilisers

Biocontrol agents and biofertilisers: organism explorer

Switch between biocontrol agents (Bacillus thuringiensis, Trichoderma, Baculovirus, ladybird, dragonfly) and biofertilisers (Rhizobium, mycorrhiza/Glomus, Anabaena/cyanobacteria, Azospirillum). Click any organism to see what it controls or enriches and the NEET fact.

Biocontrol Agents
Biofertilisers
Bacillus thuringiensis (Bt)
Trichoderma (fungus)
Baculovirus (NPV)
Ladybird beetle
Dragonfly

Bacillus thuringiensis (Bt)

Type

Bacterium (soil)

Target pest

Caterpillars (lepidopteran larvae) on crops

Mechanism

Produces protein crystals (Bt toxin) toxic to insect larvae. Farmers spray dried spore preparations on crops. Caterpillars ingest the spores, the toxin is activated in their alkaline gut and kills them. Harmless to plants, mammals and birds.

NEET fact

Bt was one of the first commercialised biocontrol agents. The cry genes from Bt are also used to create transgenic Bt crops (Bt cotton, Bt brinjal).

Organism

Controls

Bacillus thuringiensis (Bt)

Caterpillars

Trichoderma (fungus)

Plant pathogens in the soil

Baculovirus (NPV)

Insects and arthropods

Ladybird beetle

Aphids

Dragonfly

Mosquitoes

Try this

  • Compare Rhizobium and Azospirillum. Both fix nitrogen, but how do they differ in how they associate with plants?
  • Why are Baculoviruses described as ideal biocontrol agents? What makes them different from chemical pesticides?
  • Trichoderma appears in two different roles in this chapter. Can you name both roles?

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