Human Blood Groups – Class 11 | Chapter – 18 | Biology Short Notes Series PDF

Human Blood Groups: The term “blood group” refers to the entire blood group system comprising red blood cell (RBC) antigens whose specificity is controlled by a series of genes which can be allelic or linked very closely on the same chromosome. “Blood type” refers to a specific pattern of reaction to testing antisera within a given system.

Importance of Human Blood Groups

Due to the knowledge of Human Blood Groups blood donation has been proved as a boon for the society. By this if  blood is required for victims of accident and sick persons then blood of appropriate group could be made available by the blood banks or registered voluntary blood donors easily. They are important in the field of law and justice. By taking samples and tests of DNA, culprits could be caught.

There are four main Human Blood Groups. They are:-

  • Blood group A

  • Blood group B

  • Blood group AB

  • Blood group O  

Karl Landsteiner discovered the A, B, and O blood groups in 1900. After that, the AB blood group was discovered by his student Decastallo and Sturli in 1902. Two types of antigens were found in the blood group, and they were named antigen A and antigen B. In the ABO system, the presence of antigen A and antigen B determine the blood group.  

Blood group A:- A person having blood group A has the A antigen on the surface of the red blood cell (RBC) and shows the B antibodies in plasma. 

Blood group B:- A person having blood group B has B antigen on the surface of the red blood cell and shows A antibodies in plasma 

Blood group AB:- A person having blood group AB has both antigen A and B on the surface of the red blood cell and has no antibodies in the plasma. 

Blood group O:- A person having blood group O lacks antigens on the surface of the red blood cells and shows the presence of both A and B antibodies in the plasma. 

A person with a blood group O can donate blood to anyone, but someone with blood group AB can receive blood from anyone. 

These four main blood groups are further divided into eight blood groups based on their Rh factor.

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By Team Learning Mantras