NEET (UG) · Botany, Class 12
Microbes in Human Welfare: NEET PYQ, 2018–2026
Microbes in Human Welfare (Botany, Class 12) has been asked 10 times in the 7 NEET papers from 2018, 2020, 2021, 2023, 2024, 2025 and 2026: about 1.4 questions a paper, 3% of all Botany questions. It is the 16th most-asked of 17 Botany chapters. NEET 2026 had 1 from it. Last checked 28 October 2026.
Questions per paper
Year by year.
| Year | Questions |
|---|---|
| 2018 | 1 |
| 2020 | 2 |
| 2021 | 1 |
| 2023 | 0 |
| 2024 | 1 |
| 2025 | 4 |
| 2026 | 1 |
From 2021 to 2024 each paper had 200 questions (a Section B with a choice); the others had 180.
Inside the chapter
Topics asked most.
- Industrial and sewage applications7
- Microbes in household products2
- Biocontrol agents and biofertilisers1
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10 Microbes in Human Welfare questions to practise.
Our own questions, written in the NEET pattern and checked, each with an explanation. Pick an option to see the answer.
Q1 · Botany · Microbes in Human Welfare
Vinegar is produced from alcoholic liquids by a group of bacteria that oxidise ethanol to acetic acid. Which bacterium is responsible?
Answer: (A)
Principle: vinegar is made by acetic acid bacteria, which oxidise ethanol in an alcoholic liquid to acetic acid. Acetobacter aceti is the standard example. The distractors are other famous food microbes, each tied to a different product: curd, Swiss cheese and Roquefort cheese.
Q2 · Botany · Microbes in Human Welfare
Trichoderma species are used as biocontrol agents against soil-borne fungal pathogens. Which mechanism is most directly responsible for their antagonism?
Answer: (A)
Principle: Trichoderma is a free-living fungus that controls plant pathogens through mycoparasitism, coiling around pathogen hyphae and lysing their walls with chitinases and glucanases. It also competes for nutrients and space. Apply: identify the active antagonistic mechanism, which is direct parasitism of the pathogen, and distinguish it from bacteriocins, nitrogen fixation and mycorrhizal exclusion.
Q3 · Botany · Microbes in Human Welfare
Which of the following statements about statins is correct?
Answer: (D)
Statins are produced by the yeast Monascus purpureus and have been commercialised as blood-cholesterol lowering agents. They act by competitively inhibiting the enzyme responsible for the synthesis of cholesterol, so less cholesterol is made.
Q4 · Botany · Microbes in Human Welfare
Biofertilisers are considered an eco-friendly alternative to chemical fertilisers mainly because they:
Answer: (A)
Principle: biofertilisers are living microbes that enrich soil nutrients naturally, unlike chemical fertilisers which are manufactured and can pollute. Application: the sustainability advantage follows from the renewable, low-pollution nature of microbial nutrient supply. The other options either describe biocontrol agents or misstate how biofertilisers act.
Q5 · Botany · Microbes in Human Welfare
The insecticidal protein of Bacillus thuringiensis is produced inside the bacterium as an inactive crystalline protoxin. Under which condition is this protoxin converted into its active toxic form that kills a susceptible insect larva?
Answer: (B)
Principle: B. thuringiensis forms a crystal (Cry) protein during sporulation. This protein is a protoxin that is inactive in the bacterium. When an insect larva ingests it, the crystal dissolves in the alkaline environment of the larval midgut. Gut proteases then cut it into a smaller active toxin that binds to specific receptors on the midgut epithelium and forms pores, causing the larva to die. Because the activation depends on the alkaline gut of susceptible larvae and on specific receptors, the toxin is safe for humans (acidic stomach, no such receptors) and for most non-target insects. This is why Bt preparations are used as selective biocontrol sprays and why Bt genes are inserted in crops such as cotton.
Q6 · Botany · Microbes in Human Welfare
Trichoderma harzianum, a free-living soil fungus, suppresses several soil-borne fungal pathogens of crop plants. Which mechanism best accounts for this biocontrol activity?
Answer: (A)
Principle: Trichoderma species are free-living fungi that act as biocontrol agents through several mechanisms, the central one being mycoparasitism. The fungus recognises and coils around pathogen hyphae and secretes chitinases and glucanases, which hydrolyse the chitin and glucan components of the fungal cell wall. Trichoderma also competes for nutrients and space and can produce antibiotics, but direct degradation of pathogen hyphae is the key mechanism.
Q7 · Botany · Microbes in Human Welfare
Which microbe is used in brewing beer to convert the sugars of malt into ethanol and carbon dioxide?
Answer: (A)
Alcoholic beverages are made by fermenting sugary raw materials with yeast. Saccharomyces cerevisiae is the yeast used in brewing beer and making wine, and it converts sugars to ethanol and carbon dioxide under anaerobic conditions. Lactobacillus, methanogens and Penicillium are all real industrial microbes, but each is linked to a different product: curd, biogas and antibiotics respectively.
Q8 · Botany · Microbes in Human Welfare
The large holes in Swiss cheese form because a bacterium produces a gas during ripening. Which bacterium is responsible, and what gas is it?
Answer: (A)
Swiss cheese is ripened by Propionibacterium sharmanii, which ferments lactate and releases carbon dioxide. The gas gets trapped in the curd as bubbles, leaving the holes. Identify the organism first, then the gas it produces.
Q9 · Botany · Microbes in Human Welfare
Plain wheat flour dough, mixed with water and no added sugar, is fermented by yeast. What is the main source of the sugars that the yeast ferments?
Answer: (B)
Yeast cannot use starch directly in bulk. The enzymes already present in flour, mainly amylases, hydrolyse starch to maltose during dough rest. Yeast maltase then converts maltose to glucose, which is fermented anaerobically to ethanol and CO2. So the starch in the flour is the real reservoir of fermentable sugar. Free sucrose or added milk sugar are not the primary source.
Q10 · Botany · Microbes in Human Welfare
Cyclosporin A, a drug given to transplant patients to suppress immune rejection of the grafted organ, is produced industrially by which fungus?
Answer: (A)
Principle: NCERT lists specific microbes against specific industrial products. Cyclosporin A, an immunosuppressant used in organ transplantation, comes from the fungus Trichoderma polysporum. Penicillium gives penicillin, Monascus gives statins, and Clostridium is linked to solvents and acids. Learn each product with its producer.
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All 10 real NEET questions from Microbes in Human Welfare.
The questions from the actual papers, with the official answer and an explanation for each — chapter by chapter, or as full timed papers.
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About Microbes in Human Welfare in NEET.
How many questions come from Microbes in Human Welfare in NEET?
Microbes in Human Welfare (Botany, Class 12) has been asked 10 times in the 7 NEET papers from 2018, 2020, 2021, 2023, 2024, 2025 and 2026: about 1.4 questions a paper, 3% of all Botany questions. It is the 16th most-asked of 17 Botany chapters. NEET 2026 had 1 from it.
Which topics of Microbes in Human Welfare are asked most in NEET?
Industrial and sewage applications (7), Microbes in household products (2), Biocontrol agents and biofertilisers (1), counted over the papers from 2018–2026.
Is Microbes in Human Welfare important for NEET 2027?
It is in the syllabus in force, so it can be asked. By past papers it ranks 16 of 17 in Botany; use that to decide how much time it gets, not whether to study it.
Where can I solve Microbes in Human Welfare NEET previous year questions?
On Nikaalle, free: sign up and practise every past NEET question from Microbes in Human Welfare with an explanation for each, or sit the full papers timed. The ten questions on this page are our own, written in the same pattern.
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