Final answer:
The benefit of protein synthesis in polyribosomes is an increase in efficiency, allowing more protein to be produced from a single mRNA strand as multiple ribosomes work on it simultaneously.
Step-by-step explanation:
The benefit of protein synthesis in polyribosomes is that more protein can be produced from a single RNA. By having multiple ribosomes translating a single mRNA strand simultaneously, the efficiency of protein synthesis is increased. Each ribosome can translate an mRNA molecule in approximately one minute, so with polyribosomes, multiple ribosomes can produce multiple times the number of the same protein in the same minute.