Final answer:
Microbes in the rumen enable animals such as ruminants and pseudo-ruminants to digest cellulose, a complex sugar molecule in plant cell walls that animals cannot break down themselves due to the absence of cellulase.
Step-by-step explanation:
Microbes such as those found in the rumen allow animals to digest cellulose. Cellulose is a component of plant cell walls and is a challenging substance for animals to digest because they lack the enzyme cellulase. Ruminant animals, like cows and goats, have specialized stomach chambers such as the rumen and reticulum, which contain prokaryotes and protists capable of breaking down the cellulose fiber. Similarly, pseudo-ruminants like camels and alpacas also rely on microbes in their digestive system featuring a large cecum for digestion of roughage.