From the list provided pick 3 biochemical reasons why maintaining pH through buffers is important for (natural) biological processes:
Biochemists wish to replicate physiological conditions
Maintaining pH is what cells always do
Experiments need to be done at physiological pH
Ionisation state of ionisable groups need to be controlled
Enzyme-catalysed reaction rates may vary with pH
Proteins can unfold at extreme pH
The proton concentration per se is not important, but pH always matters