Separation of right side and left side of the heart is useful to keep oxygenated and deoxygenated blood from mixing. Various organisms have different types of heart.
Generated by claude-sonnet-4-6 · 2026-06-11 09:52 · grounding rag
Model Answer
(I)
| Organisms | Chambers | Type of blood | Type of circulation |
|---|---|---|---|
| Fish | (i) 2-chambered | Deoxygenated (single pass) | Single |
| (ii) Amphibians / Reptiles | 3-chambered | Mixed | Incomplete double circulation |
| Birds and Mammals | 4-chambered | Separated | (iii) Complete double circulation |
(II) Complete double circulation (found in birds and mammals) is the most efficient, as oxygenated and deoxygenated blood are completely separated, ensuring a highly efficient supply of oxygen to meet the high energy needs of warm-blooded animals.
Source: Chapter 5, Section 5.4.1 — Transportation in Human Beings
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Explanation
- (i) Fish have a 2-chambered heart (1 atrium + 1 ventricle); blood passes through the heart only once per cycle — single circulation.
- (ii) The organism with a 3-chambered heart that tolerates mixing is amphibians or many reptiles.
- (iii) In birds and mammals, blood passes through the heart twice per cycle — this is called double circulation; since there is no mixing, it is complete double circulation.
- For Part II, the examiner wants you to name the type and briefly justify it using the textbook reasoning (high energy needs, body temperature maintenance, complete separation of blood).