Which of the following pairs has a double circulation pathway?

  1. Amphibians and Mammals 
  2. Birds and Mammals 
  3. Reptiles and Mammals 
  4. Fishes and Birds

Answer (Detailed Solution Below)

Option 2 : Birds and Mammals 
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Detailed Solution

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The correct answer is birds and Mammals.

  • Birds and Mammals have a double circulatory pathway.

Key Points

  • No, mixing of oxygenated and deoxygenated blood in this pathway.
  • The ventricles pump it out without mixing which means two separate circulatory pathways are present in these organisms.
  • Hence, these animals have double circulation.
  • Fishes have single circulatory pathways of circulation which's why known as a single circulation system.
  • In this system oxygenated blood is supplied to the body from where deoxygenated blood is returned to the heart. 
  • In Amphibian and reptiles has incomplete circulation.
  • Here oxygenated and deoxygenated blood gets to mix up within the single ventricle.

Additional Information

  • Types of Circulation and Heart
Characters FIshes Amphibians Reptiles Crocodile Aves Mammals
No of heart chambers 2 3 3 4 4 4
Atria 1 2 2 2 2 2
Ventricles 1 1 1 2 2 2
Type of circulation Single Transitional double Transitional double Double Double Double
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