UPSC CAPF (AC) 2025 Paper I · Question 93
Question 93 of the UPSC CAPF (AC) 2025 Paper I (3 August 2025). Try it first, then open the answer and explanation.
Which one of the following classes demonstrates double circulation of blood?
- Invertebrates
- Fishes
- Amphibians
- Mammals
निम्नलिखित में से कौन-सा वर्ग (class) रक्त का द्विपरिसंचरण प्रदर्शित करता है?
- अकशेरुकी
- मत्स्य
- उभयचर
- स्तनधारी
Show answer
Answer: (4) Mammals
उत्तर: (4) स्तनधारी
Mammals (like birds) have a four-chambered heart that keeps oxygenated and deoxygenated blood fully separate, so blood passes through the heart twice in each round, once in the pulmonary and once in the systemic circuit: complete double circulation. Fishes have single circulation, and in amphibians blood mixes in the single ventricle of the three-chambered heart, so their double circulation is only incomplete.