Rhizopus, being a fungus, exhibits extracellular digestion, secreting enzymes onto its food source to break down complex molecules into simpler, absorbable substances. 

Rhizopus, as a fungus, is a saprophyte, meaning it obtains nutrients from dead and decaying organic matter. Instead of ingesting food and digesting it internally, fungi like Rhizopus employ extracellular digestion. Rhizopus secretes enzymes, which are enzymes like amylase and cellulase, onto the food substrate (like bread) to break down complex molecules (like starch and cellulose) into simpler, soluble substances. 

These simpler, soluble molecules are then absorbed into the fungal hyphae (filaments) through the fungal cell walls by diffusion, where they are then utilized for metabolism.