I was just browsing through the biochemistry and biophysics tabs and noticed a question that was commented as being "off topic" and better posted in the Chemistry SE.
Yes, this is a pretty basic thermo question that could have belonged in Chemistry.SE, but I thought it was reasonable to ask here. Also, this is not a great question in terms of quality, so I'm not mortified at it not getting an answer. However, as an example it got me thinking.
The concept is really fundamental to understanding biochemistry and biophysics. The only reason this doesn't have a "a strong biological component" (according to the commenter) is because its a theoretical model question, but theoretical models are a big part of biology! If this person asked about measuring the O2 binding energies of haemoglobin vs myoglobin, that is a classic biochemistry question, and uses the exact same kind of analytical framework. Surely that question would not be off-topic here. The only real difference is that one is pure theoretical and the other is slightly more concrete.
One last example - questions about the continuum elastic model of a membrane. Questions about the theoretical underpinning of the model might belong in Physics.SE, as they discuss elastic moduli, stress, strain and all that good physics stuff. But a question about applying that model to an actual membrane would certainly belong in Biology.SE. Its unlikely anyone on Physics.SE would know or care about the properties of different membrane compositions, or care about the interactions between membranes and peptides or transmembrane proteins. It therefore seems weird to force questions about the underlying model elsewhere.
I think its a worthwhile question as to how we treat purely theoretical biochemistry or biophysics questions. Biology is generally a big tent, accepting methodologies and frameworks from all sorts of other fields, and I think discussion of those models belongs here too.