Complex sentence: This lets the model more accurately simulate real metabolism and can be thought of biologically in two subsets; constraints that limit nutrient uptake and excretion and those that limit the flux through reactions within the organism.
Split into simpler sentences: This lets the model more accurately simulate real metabolism. The constraints can be thought of as belonging to two subsets from a biological perspective; constraints that limit nutrient uptake and excretion and those that limit the flux through reactions within the organism.