"To model the system" means to create a simplified representation or simulation of how a system works. It helps us understand and analyze the system before implementing it in the real world. Full definition
Here we extend this work by looking at embryos as model systems for following bacterial infection in real time. (journals.plos.org)
The value of spiders, particularly web - building spiders, as model systems for sexual selection is becoming increasingly evident [1], [2]. (journals.plos.org)
And we've learned a lot about that in model systems, such as in fruit flies, worms, and mice. (discovermagazine.com)