  We introduce the concept of minimum edge cover for an induced subgraph in a
graph. Let $G$ be a unicyclic graph with a unique odd cycle and $I=I(G)$ be its
edge ideal. We compute the exact values of all symbolic defects of $I$ using
the concept of minimum edge cover for an induced subgraph in a graph. We
describe one method to find the quasi-polynomial associated with the symbolic
defects of edge ideal $I$. We classify the class of unicyclic graphs when some
power of maximal ideal annihilates $ I^{(s)}/I^s $ for any fixed $ s $. Also
for those class of graphs, we compute the Hilbert function of the module
$I^{(s)}/I^s$ for all $s.$
