A certain road accident patien with unknown blood group needs immediate blood transfusion. His one docter friend at once offers his blood .What was the blood group of the doner ?

Blood group is tested by two types of sera, i.e., anti -A (antibody -A) and anti-B (antibody-B). Persons with blood group O possess both antibodies in their plasma but have no antigens in their RBCs. So, RBCs of blood group 'O' do not show clumping in any of the two sera. That 's why, persons with blood group 'O' are called universal donor and they can donate blood to a person with any type of blood group.