(a) Schematic diagram of the negative feedback system with end-product utilisation. (b, c, d) The K1 vs. n1 bifurcation diagram for the system with end-product utilisation. (b) Bifurcation diagram comparison between system without end-product utilisation and one with utilisation on K1-n1 plane (G = 0.2 was used). (b) Bifurcation diagram of system with utilisation for increasing G (G = 0.2, 0.4, 0.8 were used). (c) Two-parameter K1 vs. g bifurcation diagrams for n1 = 2, 4 and 6; oscillatory regions are in red (parameter set k1 = 1, k2 = 2, k3 = 1, k4 = 1, kd1 = 1.2, kd2 = 3, kd3 = 2, kd4 = 1 was used).