Answer:
Part A:
Saprotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of dead or decayed organic matter. It occurs in saprotrophs or heterotrophs and is most often associated with fungi, for example, Mucor and Rhizopus.
Part B:
The reason saprophytes are so beneficial to the environment is that they are the primary recyclers of nutrients. They break down organic matter so that the nitrogen, carbon, and minerals it contains can be put back into a form that other living organisms can take up and use.