Answer:
AB type blood consists of RCB's having both 'a' and 'b' type antigens on their surface. Thus any possibility of cross reaction with any other similar peptide and generation of anti-A and anti-B is not possible, because self antigens do not elicit immune response and do not produce any antibody specific to them.
The screening of the nuclear charge by core electrons in atoms IS MORE EFFICIENT THAN THAT BY VALENCE ELECTRON.
Screening effect refers to the reduction in the effective nuclear charge on the electron cloud due to a difference in the attraction forces of the electrons on the nucleus.<span />