Question

why blood group O cannot take blood from A or B

Answer 1

see there are 4 types of blood group -
1) A
2)B
3)AB
4)O
so now we are talking about o

in o , antigen is absent and antibody is present which is Anti gen a and b and because of antigen o cannot take blood from a and b (same antibody will clot with same blood group) so that's why it can only take blood by o and also in AB antigen is present but antibody is absent so it can take blood from any one ......
hope it helps you