<<xlr8r.m

model={{(Overscript[A⇄B, ℰ]),k1,k2,k3}};

Species as a parameter is stepped

predictions=PredictTransferFunction[model, {t,0,10}, {k1,0,1,.1}, B, 
initialConditions-> {A-> 1,B->0, ℰ-> 1},
rates-> {k2-> .5, k3-> 1}];

ListPlot[Most[predictions], Joined-> True, PlotMarkers-> Automatic,Frame-> True,  FrameLabel-> {"k1", "B[10]"}]

Species as IC is stepped

predictions=PredictTransferFunction[model, {t,0,10}, {ℰ,0,5,.1}, B, 
initialConditions-> {A-> 1,B->0},
rates-> {k1-> 1, k2-> .5, k3-> 1}];

ListPlot[Most[predictions], Joined-> True, PlotMarkers-> Automatic,Frame-> True,  FrameLabel-> {"ℰ[0]", "B[10]"}]