Class 12 Biology Reproduction In Organisms Asexual reproduction
  • The reproduction in which an offspring is produced by single parent without the fusion of gametes is called asexual reproduction.
  • A single parent produces offspring and the off springs are exact copies of their parents.
  • The off springs are genetically and morphologically similar and are referred to as clones.
  • Characteristics of asexual reproduction
  • A single parent is involved and so no fusion of gametes.
  • Only mitosis takes place.
  • Rapid multiplication.

Modes of asexual reproduction

  • Binary fission- the parent body divides in to two equal halves and each half grows in to an adult.

Example- Amoeba, Paramecium.

Fig. binary fission in amoeba

  • Budding- small bud is produced due to the cell division at one particular site which remains attached initially to the parent cell and eventually gets separated and matures into a new individual.

 

Example- yeast

Fig. budding in yeast

Asexual reproductive structures-

  • Members of kingdom fungi and simple plants reproduce through special reproductive microscopic motile structures called as Example- chlamydomonas
  • Other common structures are conidia in Penicillium, buds in Hydra, gemmules in sponge.

Vegetative propagation-

In plants, the vegetative parts of the body of the plant called as vegetative propagules give rise to new offspring

  • Example- runner, rhizome of ginger, suckers of chrysanthemum, offset of water hyacinth, bulb of onion, eyes of potato can give rise to new offspring.

Vegetative propagules develop from some other specialized parts present in the vegetative propagules.

  • Example- eyes of  potato, rhizomes of  banana, ginger arise from nodes present in the modified stem of these plants , adventitious buds of Bryophyllum arise from the notches present at margin of leaves.

As the progenies arise from a single parent, the progenies do not show genetic variation and do not contribute to evolution.

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