Science: How Do Organisms Reproduce

 SCIENCE 

HOW DO ORGANISMS REPRODUCE?

Introduction

Reproduction

Reproduction is the process by which all organisms multiply in number and increase their population.

Asexual reproduction

Asexual reproduction is a method of reproduction that involves only one organism. A single organism reproduces two or multiple organisms on its own. This is seen in all unicellular organisms, some multicellular organisms and a few plants.

Types of Asexual Reproduction:

pratham14815

      Fission:-

• Fission is an asexual reproduction that is common in most of the unicellular organisms.
• When the fission results in two daughter cells, it is binary fission (e.g. paramecium).When fission results in many daughter cells, it is called multiple fission (e.g. Plasmodium).Planes of fission may be different for different organisms.

  Budding

  • Budding is a type of asexual reproduction in which a small cyst-like structure is formed on the parent’s body, which gives rise to a new individual.
  • Bud may remain attached to the parent (yeast) or may separate and become a new individual (hydra).

  

  pratham14815

  

  pratham14815

  Regeneration and fragmentation

  • Regeneration is the process of growing back the lost organ or body part by the organism (e.g. lizard).
  • Fragmentation is the process by which an organism gets fragmented into smaller pieces and each piece grows into a whole new organism.
  • E.g. Planaria, Hydra
    

  Spore formation

  Organisms such as fungi make spores that can grow into complete new individuals when dispersed from their fruiting body.

  

  pratham14815
  

  Vegetative propagation

  • This is a type of asexual reproduction seen in plants.
  • The vegetative part of the plant, like leaves, stem, roots, gives rise to a new plant.
  • Vegetative propagation can be artificial or natural.
  • Natural vegetative propagation happens through leaves (e.g. bryophyllum), stem (e.g. turmeric, ginger), runners/stolon (e.g. grass runners, strawberry), bulbs ( e.g. onion, lily), etc.
  • Artificial methods include cutting, grafting, layering and plant tissue culture.
    

  
  
  
  

  

  pratham14815