Final answer:
Termites have a mutualistic relationship with Trichonympha protozoa in their guts, which helps them digest wood. The enzyme cellulase is responsible for breaking down cellulose into glucose monomers that termites can utilize as an energy source.
Step-by-step explanation:
Termites have a mutualistic relationship with a protozoan called Trichonympha. The protozoan lives in the termite's gut and helps digest cellulose, which is found in wood.
The digestive enzyme that breaks down cellulose is called cellulase. Termites rely on bacteria and other microorganisms in their bodies to produce this enzyme, which breaks down cellulose into glucose monomers that can be used as an energy source.