PLAS CODE : S' = al (a2 - S - a3 N) S N' = b1 (b2 - N - b3 S) N al = 0. 005 a2 = 60 a3 = 2.5 b1 = 0.02 b2 = 30 b3 = 1 1. Which of the parameters describe the direct interactions between the two species? In the absence of either one of the two species, what are the carrying capacities of F and N? 2. Design a phase-plane plot containing all of the typical elements: All nullclines, steady-state points with indication whether they are stable or not, and representative trajectories. How do these trajectories cross the different nullclines? Finish the PLAS code and generate the plots to confirm the validity of the trajectories you just established