ASEXUAL REPRODUCTION

What is Asexual reproduction? Asexual reproduction is the formation of offspring from a single parent.

The offspring are identical to the parent.

Types of asexual reproduction.

  1. Binary fission in amoeba.
  2. Spore formation in Rhizopus.
  3. Budding in yeast.

Binary fission

This involves the division of the parent organism into two daughter cells. The nucleus first divides into two and then the cytoplasm separates into two portions. Binary fission also occurs in bacteria, Paramecium, Trypanosoma and Euglena.

Spore formation in Rhizopus

Rhizopus is a saprophytic fungus which grows on various substrate such as bread, rotting fruits or other decaying organic matter. The vegetative body is called mycelium which has many branched threads called hyphae.

Horizontal hyphae are called stolons. Vertical hyphae are called sporangiophore. The tips of sporangiophore become swollen to form sporangia, the spore bearing structure.

Each sporangium contains many spores. As it matures and ripens, it turns black in colour. When fully mature the sporangium wall burst and release spores which are dispersed by wind or insects.

When spores land on moist substratum, they germinate and grow into a new Rhizopus and start another generation.

Spore formation in ferns

The fern plant is called a sporophyte. On the lower side of the mature leaves are sari (Singular: sorus) which bear spores.

Budding in Yeast

Budding involves the formation of a protrusion called a bud from the body of the organism. The bud separates from the parent cell, in yeast budding goes on so fast and the first bud starts to form another bud before the separation. A short chain or mass of cells is formed.

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