UPSC Prelims 2002·GS1·science-and-technology·science and technology

Which one of the following statements is correct?

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Last updated 23 May 2026, 3:31 pm IST
  1. AAll echinoderms are viviparous
  2. BRound worm has no circulatory system
  3. CIn bony fishes, swim bladder is usually presentCorrect
  4. DIn cartilaginous fishes, fertilisation is internal

Explanation

In bony fishes (Osteichthyes), the swim bladder is usually present. It is a gas-filled organ that helps the fish control its buoyancy and maintain its position in the water column without expending energy on swimming. Option A is incorrect because echinoderms (such as starfish and sea urchins) are predominantly oviparous, meaning they lay eggs and exhibit external fertilization. They are not viviparous. Options B and D are also scientifically accurate: roundworms (nematodes) lack a formal circulatory system, relying on diffusion, and cartilaginous fishes (sharks and rays) do have internal fertilization.
science-and-technology: Which one of the following statements is correct?
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