Assertion (A): In the human heart, there is no mixing  of oxygenated and deoxygenated blood.  

Reason (R): Valves are present in the heart which  allows the movement of blood in one direction  only.  



  • The human heart has 4 different chambers which prevent mixing of oxygenated and deoxygenated blood due to the partition between two sides called septum
  • Valves are present in the heart to prevent backflow of blood i.e., to allow the movement of blood in one direction only.  


  • The assertion is True
  • The reason is True
  • But the reason is not the correct explanation for the assertion.


So, the correct answer is (b).

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Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 14 years and a teacher from the past 18 years. He teaches Science, Economics, Accounting and English at Teachoo