the ABO blood group of student 1 is A. Determine the ABO blood types of the other 4 students & explain clearly

Question

red blood cells from student

1 2 3 4 5
blood serum from student 1 - - + - +
2 + - + + +
3 - - - - -
4 - - + - +
5 + - + + -

use this table to answer the question

Answer 1

1 --+-+
2 +-+++
3 -----
4 --+-+
5 +-++-

if 1 is blood group A, they have A antigens and anti-B antibodies. They will not, of course, agglutinate with themselves. Dropping A blood into AB blood will not agglutinate. But dropping A blood into B or O blood will agglutinate (they have anti-A)

3 is group O, a universal donor which you can drop into any of the other blood groups without any agglutination
2 is group AB, universal acceptor but if you drop AB blood into any other blood group, it will agglutinate (as they will have anti A or anti B or both)
5 is blood group B
4 is blood group A with identical agglutination pattern to 1