Q. 4 A4.1( 67 Votes )
Asexual reproduction in unicellular organisms
1. Binary Fission:
The parent cell divides to form two similar daughter cells is called Binary fission. It occurs either by mitosis or amitosis.eg: Prokaryotes (Bacteria), Protista (Amoeba, Paramecium, Euglena, etc.) and eukaryotic cell-organelle like mitochondria and chloroplasts perform asexual reproduction by binary fission.
2. Multiple Fission
Multiple fission usually found in Amoeba and other similar
Protista. Amoeba stops the formation of pseudopodia and thereby movements whenever there is lack of food or any other type of adverse condition. It becomes rounded and forms a protective covering around plasma membrane. Such encysted Amoeba or any other protistis called as ‘Cyst’. Many nuclei are formed by repeated nuclear divisions in the cyst. It is followed by cytoplasmic division and thus, many amoebulae are formed. They remain encysted till
there are adverse conditions. Cyst breaks open on arrival of favorable conditions and many amoebulae are released.
In budding a small bud comes out of many parent cells. It occurs by budding in yeast- a unicellular fungus. A small bulge appears on the surface of parent cell. This bulge is actually a bud. One of the two daughter nuclei enters this bud. After sufficient growth, bud separates from the parent cell and starts to live independently as a daughter yeast cell. Yeast cell produces two daughter nuclei by mitotic division by budding. This yeast cell is called as parent cell.
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