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Science — AI-generated practice question

AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.

Q1. [1] medium thorough-understanding
In the context of blood circulation, what is meant by 'double circulation', and which animals exhibit it?
  1. a Blood passes through the heart once per body cycle; seen in fishes.
  2. b Blood passes through the heart twice per body cycle; seen in birds and mammals.
  3. c Blood passes through the heart twice per body cycle; seen in amphibians and reptiles.
  4. d Blood is pumped to gills first and then to the body; seen in all vertebrates.
Generated by claude-sonnet-4-6 · 2026-06-15 06:44 · grounding rag
Model Answer

Option (b) is correct. Double circulation means blood passes through the heart twice per body cycle — once through the lungs (pulmonary) and once through the body (systemic). It is seen in birds and mammals.

Source: Life Processes, Section 5.4.1

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Explanation

The passage clearly states: "blood goes through the heart twice during each cycle in other vertebrates. This is known as double circulation." It also specifies that complete separation of oxygenated and de-oxygenated blood is useful for animals with high energy needs — birds and mammals. Option (a) describes fishes (single circulation), (c) is wrong because amphibians/reptiles have three-chambered hearts with some mixing but the term "double circulation" applies to birds and mammals, and (d) describes fish circulation specifically.

Previous-year CBSE Grade 10 board exam questions, organised by subject and chapter, each with a model answer — free to read and print.