Gibbs Free Energy

The relation between standard free energy and biologically standard free energy is given by:

(delta)G|biological = (delta)G|standard +RTln(10^-7)

where under biological condition the pH is 7 instead of 0 (1M H3O+).

I know the free energy is given by:

(delta)G = (delta)H - T(delta)S = (delta)H - T(delta)S|non-mixing -T(delta)S|mixing = (delta)H - T(delta)S|non-mixing +RTln(Q) = (delta)G|standard + RTln(Q)

But how can I derive the term RTln(10^-7)?

I think if my biochemical equation does not have a hydroxide or a hydronium on either sides should have its free energy pH independent... Where did it go wrong? Hope someone to point out...