Trees with light brown bark dominate an ecosystem. The ecosystem has populations of insects that thrive on the tree bark. Over time, some insect species developed certain physical characteristics that helped them thrive on the tree bark. These physical characteristics also helped the insects defend themselves from predators. Which insect species is probably the species with the new physical characteristics?

I'm assuming this is referring to the Peppered Moth, a species of moth that adapted to the change of color on tree bark. The tree bark changed color as a result of local pollution. The moths (over the course of generations) changed color as well that better suited camouflage upon the new color of the tree bark.

an active site is a region that is present on an enzyme where the reactants or the substrate molecules we can say bind and experience a chemical reaction. the substrate is basically a reactant whose concentration is changing and that is converting into a product after binding at the active site of an enzyme