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Curiosity

Class 8 · Science & Environment

Ch 2 · The Invisible Living World: Beyond Our Naked Eye

Real UPSC Prelims questions from 2016–2026, linked to this book. Try each one first, then open the answer. 2026 answers follow UPSC's provisional answer key.

Prelims 2021 · Q22

Consider the following kinds of organisms:

  1. 1.Copepods
  2. 2.Cyanobacteria
  3. 3.Diatoms
  4. 4.Foraminifera

Which of the above are primary producers in the food chains of oceans?

  1. (a)1 and 2
  2. (b)2 and 3
  3. (c)3 and 4
  4. (d)1 and 4
Show answer

UPSC's answer: (b)

NCERT answers it: Class 12 Biology, Ch 11 (Organisms and Populations); Class 8 Curiosity, Ch 2 (The Invisible Living World: Beyond Our Naked Eye).

How to solve it with NCERT: Class 12 Biology, ch 11: cyanobacteria photosynthesise, and copepods live as parasites on fish, so they are consumers. Class 8 Curiosity, ch 2: diatoms are microalgae that make their own food using sunlight. So 2 and 3 are producers. Answer (b).

Hindi version: UPSC's official question paper (2021), question 22 ↗

Prelims 2021 · Q69

Consider the following:

  1. 1.Bacteria
  2. 2.Fungi
  3. 3.Virus

Which of the above can be cultured in artificial/synthetic medium?

  1. (a)1 and 2 only
  2. (b)2 and 3 only
  3. (c)1 and 3 only
  4. (d)1, 2 and 3
Show answer

UPSC's answer: (a)

NCERT answers it: Class 8 Curiosity, Ch 2 (The Invisible Living World: Beyond Our Naked Eye); Class 12 Biology, Ch 8 (Microbes in Human Welfare).

Class 12 Biology, ch 8 shows colonies of bacteria and of fungi growing in petri dishes. Class 8 Curiosity, ch 2: viruses multiply only after they enter a living cell, so they can't grow on an artificial medium. Answer (a).

Hindi version: UPSC's official question paper (2021), question 69 ↗

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