How do protozoa perform holozoic nutrition?

Protozoa feed using a method called holozoic nutrition, which takes place in five main steps — ingestion, digestion, absorption, assimilation, and egestion. They use a process known as phagocytosis during ingestion. In this process, protozoa extend parts of their body (like pseudopods) to surround and take in food particles such as bacteria, algae, or tiny microorganisms. The food gets enclosed in a small sac called a food vacuole. Inside this vacuole, digestion happens with the help of enzymes from lysosomes. The digested nutrients are then absorbed, used for energy and growth, and the waste is finally removed from the cell.

Five Steps of Holozoic Nutrition in Protozoa

1. Ingestion:

• The protozoan uses its pseudopods (in amoeba) or other feeding structures to capture food.
• This process of taking in solid food is called phagocytosis.
• The food gets trapped inside a food vacuole, a small bubble-like structure within the cell.

2. Digestion:

• Lysosomes containing digestive enzymes combine with the food vacuole.
• These enzymes break complex food into simple, soluble substances.
• For example, proteases break down proteins into amino acids, and other enzymes break carbohydrates into sugars.

3. Absorption: The simple nutrients from digestion move out of the food vacuole and spread into the cytoplasm.

4. Assimilation: The absorbed nutrients are used by the protozoan for energy, growth, and other cell functions.

5. Egestion: The leftover, undigested material is pushed out of the cell through the cell membrane as waste.