Question

Describe how an amoeba captures food particles.

Answer 1

Amoebae capture food by phagocytosis — they surround and ingest particles using flexible extensions of their cell body called pseudopodia. The process, in steps, is:

1. Detection and approach: The amoeba senses nearby food (bacteria, algae, detritus) and moves toward it by cytoplasmic streaming.
2. Pseudopod extension: The cytoskeleton (actin filaments) reorganizes so the cell pushes out one or more pseudopodia that flow around the particle.
3. Engulfment and vacuole formation: The pseudopodia meet and fuse around the particle, enclosing it in a membrane-bound compartment called a food vacuole (phagosome).
4. Digestion: Lysosomes fuse with the phagosome to form a phagolysosome; hydrolytic enzymes and an acidic environment break the particle down into soluble nutrients.
5. Absorption and egestion: Digested molecules diffuse into the cytoplasm for use. Any indigestible residue is expelled when the vacuole membrane fuses with the cell membrane (exocytosis).

This intracellular digestion using pseudopodia and lysosomal enzymes is how amoebae obtain and process their food.