Class 12 · Microbes in Human Welfare

Microbial Diversity and Extreme Habitats — NEET Biology

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📖 NCERT Source

Besides macroscopic plants and animals, microbes are the major components of biological systems on this earth. You have studied about the diversity of living organisms in Class XI. Do you remember which Kingdoms among the living organisms contain micro-organisms? Which are the ones that are only microscopic? Microbes are present everywhere – in soil, water, air, inside our bodies and that of other animals and plants. They are present even at sites where no other life-form could possibly exist – sites such as deep inside the geysers (thermal vents) where the temperature may be as high as 100°C, deep in the soil, under the layers of snow several metres thick, and in highly acidic environments. Microbes are diverse – protozoa, bacteria, fungi and microscopic animal and plant viruses, viroids and also prions that are proteinaceous infectious agents. Some of the microbes and 8.2.

NCERT Biology · Class 12 · Chapter 8 · Paragraph 1
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Assertion (A): All microbes are useful to humans in diverse ways. Reason (R): Microbes are present everywhere in soil, water, air, and inside living organisms.

📖 Solution & NCERT Explanation
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Correct answer: D If the assertion is false but the reason is true.

NCERT explicitly states “several microbes are useful to man in diverse ways” - the qualifier “several” indicates only some microbes are useful, not all. The Assertion removes this qualifier making it false since many microbes are pathogenic as mentioned earlier in NCERT. The Reason is independently true from NCERT: “Microbes are present everywhere – in soil, water, air, inside our bodies and that of other animals and plants.”

❓ Frequently Asked Questions
What does NCERT say about Besides macroscopic plants and?
Besides macroscopic plants and animals, microbes are the major components of biological systems on this earth. You have studied about the diversity of living organisms in Class XI.
Has this concept appeared in NEET?
Practice this NCERT concept with questions on MedicNEET.
Which chapter is this from?
Microbes in Human Welfare, Class 12 NCERT Biology.

Through deep analysis of NEET and NTA, 176 of the 180 ReNEET 2026 (June 21) questions were already in the MedicNEET question bank before the exam.

176/180
of the ReNEET 2026 paper (all subjects) was already in the MedicNEET question bank

MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.

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