Vulcan blood is presumed to be green in color , the explanation for this ( first definitely advanced in the installment  Obsession ,  from the original program ) being that the oxiferous ( oxygen-carrying ) protein hemoglobin , in Vulcan blood cells , is chemically based on the element copper , rather than the element iron as is the case with ...
SECONDARY GROUPS The term secondary group has come into use in sociology to describe any group which lacks one or more of the elements that go together to characterize a primary group. In general, a secondary group is composed of individuals who lacks strong emotional ties one another.. (end of quotation) .
Social identity explanation. Majority-Hogg and Abraham, according to this theory, people classify themselves as belonging to a particular social group-football club and focuses on referent social influence-the pressure to comform with the norms set by a group because we have defined ourselves as a member of that group.