compare and contrast the different types of asexual reproduction on the basis of the process, structures formed and the organisms in which it is found.
Answers
Various types of asexual reproduction are :
1) Fission - Division of the parent body into two or more daughter individuals identical to the parent. It is of two types:
(i) Binary fission: In this process, the parent organism divides into two halves, each half forms an independent daughter organism. E.g., bacteria, protozoans.
(ii) Multiple fission: Here the parent body divides into many daughter organisms. E.g., Amoeba, Plasmodium.
2) Budding- Formation of a daughter individual from a small projection, the bud, arising on the parent body is called budding. It occurs in Hydra, Scypha.
3) Strobilisation- In this process, a series of a ring-like transverse constriction are developed, organism looks like a pile of minute saucers. The segmented body is called a strobila. E.g., Aurelia.
4) Fragmentation- Here, the parent body breaks into two or more fragments. Each fragment develops into an organism. E.g., sponges, sea anemones, echinoderms.
5) Gemmae- These are specialised structures which are green, multicellular, asexual buds, which develop in a small receptacles called gemma cups located on the thalli. Its is found in liverworts (e.g., Marchantia).
6) Regeneration- Formation of the whole body of an organism from a small fragment or the replacement of the lost part. E.g., Planaria.
7) Spore formation- Spores are propagules which germinate to produce new individuals. There are several kinds of spores. These are zoospores, sporangiospores, chlamydospores, oidia conidia.
8) Vegetative reproduction- It is the formation of new plants from vegetative units such as buds, tubers, rhizomes, etc. These vegetative units are called as vegetative propagules.