Class IX, BIOLOGY, "Unicellular Organism (Amoeba)"

Unicellular Organism (Amoeba)

The organisms consisting of only one cell are called unicellular organisms e.g. Amoeba, Paramecium etc.

Amoeba
1. It is mostly found in fresh water pond or pool.
2. In the ponds, it is found moving about around the weeds and stones. Some species are found in the moist soil.
3. Amoeba is a large protist.
4. It does not have the permanent shape.
5. Its size is about the end of pin or it measures about 0.25mm. Therefore it is observed under the microscope.
6. Its structure is very simple.
7. It consists of nucleus and cytoplasm, which are surrounded by a cell membrane.
8. Cell membrane protects it.
9. Cytoplasm is divided into two parts. Outer clear and transparent part is called ectoplasm while the inner, viscous, translucent and granular part is called endplasm.
10. Endoplasm contains food vacuoles of different sizes. These food vacuoles help in the digestion of food.
11. The food of Amoeba consists of microbes present in the water of pond.
12. Contractile vacuole maintains the concentration of water in the body. It removes surplus water out of the cell.
13. In Amoeba, the exchange of gases and removal of waste.
14. In Amoeba, there are also present mitochondria, golgi bodies and ribosomes.
15. Nucleus changes its place with the movement of the organism.