  We study the stochastic resonance (SR) of a flexible polymer chain crossing
over a piecewise linear bistable potential. The dependence of signal to noise
ratio $SNR$ on noise intensity $D$, coupling constant $k$ and polymer length
$N$ is studied via two state approximation. We find that the response of signal
to the background noise strength is significant at optimum values of $D_{opt}$,
$k_{opt}$ and $N_{opt}$ which suggests novel means of manipulating proteins or
vesicles. Furthermore, the thermally activated barrier crossing rate $r_{k}$
for the flexible polymer chain is studied. We find that the crossing rate
$r_{k}$ exhibits an optimal value at an optimal coupling constant $k_{opt}$;
$k_{opt}$ decreases with $N$. As the chain length $N$ increases, the escape
rate for the center of mass $r_{k}$ monotonously decreases. On the other hand,
the crossing rate for the portion of polymer segment $r_s$ increases and
saturates to a constant rate as $N$ steps up.
