  Open chemical reaction systems involve matter-exchange with the surroundings.
As a result, species can accumulate inside a system during the course of the
reaction. We study the role of network topology in governing the concentration
build-up inside a fixed reaction volume at steady state, particularly focusing
on the effect of additional paths. The problem is akin to that in traffic
networks where an extra route, surprisingly, can increase the overall travel
time. This is known as the Braess' paradox. Here, we report chemical analogues
of such a paradox in suitably chosen reaction networks, where extra reaction
step(s) can inflate the total concentration, denoted as `load', at steady
state. It is shown that, such counter-intuitive behavior emerges in a
qualitatively similar pattern in networks of varying complexities. We then
explore how such extra routes affect the load in a biochemical scheme of uric
acid degradation. From a thorough analysis of this network, we propose a
functional role of some decomposition steps that can trim the load, indicating
the importance of the latter in the evolution of reaction mechanisms in living
matter.
