1. The Standard model is an SU(3)xSU(2)xU(1) symmetric theory. To me this means that if you choose any 3 members of the groups and act on the Lagrangian, it is invariant. However, not all terms in the Lagrangian have something for a group member to act on, for example terms that dont involve anything with colour charge aren't acted on by SU(3). Then such a term would only have SU(2)xU(1) symmetry. Do we just say that this term has the full symmetry, but there is nothing for the SU(3) part to act on? 2. In a chirally symmetric theory with (say) 2 massless fermions, the L and R handed parts of the Dirac equation can be separated leaving us with a U(2)xU(2) symmetry of the Dirac part. But now what is the symmetry of the bosonic part involving the field strength tensor? It isnt U(2)xU(2), it is the original SU(2) symmetry. How can the theory then said to be invariant under U(2)xU(2) 3. Finally, what are the symmetry transformations associated with the following conserved quantities: baryon number lepton number strangeness charmness topness bottomness and why aren't there conserved upness and downness numbers?