Reproduction Part-1

Reproduction

  • Reproduction is the process by which all organisms multiply in number and increase their population.
  • It is an essential process for the existence of a species and the continuation of life.

Asexual Reproduction

  • It is a method of reproduction that involves only one organism.
  • A single organism reproduces two or multiple organisms on its own.
  • The majority of multicellular organisms, some plants, and all unicellular species exhibit asexual reproduction.

Fission

  • Most unicellular organisms reproduce asexually through fission,
  • 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).

Regeneration and Fragmentation

  • Regeneration is the process of growing back the lost organ or body part by the organism (e.g. lizard).
  • The process of fragmentation is the division of an organism into smaller pieces, each of which develops into a new organism.
  • E.g. Planaria, Hydra

Budding

  • Budding is a type of asexual reproduction which occurs when a small structure resembling a cyst develops on the body of the parent, giving rise to a new individual.
  • Bud may remain attached to the parent (yeast) or may separate and become a new individual (hydra).

Spore Formation

  • Some organisms, like fungus, produce spores that, when released from their fruiting bodies, can develop into completely new individuals.
  • Spores are produced inside sporangia. They are covered by a thick outer layer that protects them in adverse conditions.
  • Spores germinate and start to grow when they are exposed to suitable conditions in the environment.

Vegetative Propagation

  • The vegetative parts of the plant, like leaves, stems, and roots, give 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.
  • Layering and cutting are the two common methods used for vegetative propagation. For example, banana, rose, jasmine etc.  
  • The plant produced through vegetative propagation is genetically identical to the parent plant.