Use the Fit Model platform. Enter Amax as Y. Select BC and the nominal grouping column and choose "Full Factorial" in the Macros drop-down menu. Then you get a model with one nominal and one continuous independent variable plus their interaction (often called ANCOVA).
In the report, look in the "Effect Tests" table box. If the p-value for the grouping column is low (e.g. <0.05) the groups differ. If the BC p-value is low, BC has a significant (linear) relationship with Amax, and finally, if the interaction term p-value is low, the Amax-BC slopes are significantly different between the two groups.