It is a chemical process which enables heterotrophs to obtain energy without oxygen.
Protists obtain food in 3 ways. They produce their own organic molecules, ingest, and absorb. Ingestive protists ingest food, or engulf bacteria. These protists extend their cell wall and cell membrane forming a food vacuole around the food item. Inside the food vacuole, enzymes digest the food. Absorptive protists on the other hand, absorb food molecules across their cell membrane which takes place through diffusion. Absorptive protists play a key role in decomposition. They are considered as important decomposers. Major producers like photosynthetic protists use light energy to manufacture their own food.<span>
</span>
