Q.Draw a neat labelled diagram of Paramecium.

Structure of Paramecium

Paramecium is a single-celled ciliate protozoan, yet it behaves almost like a tiny animal — it swims, hunts, feeds, digests, removes waste and controls its water balance, all within one cell. To manage all this, its structure is far more organised than a "simple" cell, and every part earns its place.

Shape and the covering

Paramecium is famously slipper-shaped, which is why it is nicknamed the slipper animalcule. Its body is bounded by a firm but elastic pellicle that gives it a fixed shape while still allowing slight flexing. Piercing the pellicle in orderly rows are thousands of tiny hair-like cilia. Their coordinated, wave-like beating is what drives the cell forward and lets it turn — cilia are the reason a ciliate can be a strong, controlled swimmer.

Feeding structures

On one side runs a slanting depression, the oral groove, which funnels food-laden water toward a mouth-like opening called the cytostome. Cilia lining the groove sweep in bacteria and other particles. Food collected here is packaged into food vacuoles, which circulate through the cytoplasm while enzymes digest the contents; undigested matter is thrown out at a fixed spot called the cytopyge (anal pore).

Water balance

Because Paramecium lives in freshwater, water constantly floods in by osmosis. To avoid bursting, it has two star-shaped contractile vacuoles that collect this excess water and periodically pump it out — a neat example of osmoregulation in a single cell.

The two nuclei …