Request a call back

Join NOW to get access to exclusive study material for best results

Asexual Reproduction in Organisms

Asexual Reproduction in Organisms Synopsis

Synopsis

 

Reproduction

  • The period from birth to the natural death of an organism is called its lifespan.
  • Reproduction is defined as a biological process in which an organism gives rise to an offspring similar to itself.

 

Events in Reproduction

 

 

Features of Reproduction

  • Replication of DNA
  • Cell division 
  • Formation of reproductive bodies or units 
  • Development of reproductive bodies into offspring

 

Significance of Reproduction

  • Reproduction ensures continuity of life on the Earth, while sexual reproduction provides great scope for variation.
  • Variation is important for survival of species.
  • Variation helps species to adapt to different environmental changes.

 

Types of Reproduction

 

 

Asexual Reproduction 

 

The process by which offspring is produced by a single parent with or without the formation of gametes is called asexual reproduction.

 

Characteristics of Asexual Reproduction

  • A single parent is involved.
  • Gametes are not formed.
  • Involves only mitotic cell division.
  • Offspring are genetically identical to the parent. They are called clones.
  • No mixing of genetic material, hence does not promote variation and evolution.

 

Sexual Reproduction 

Sexual reproduction is the development of new individuals through the formation and fusion of gametes produced either by the same individual or by different individuals of the opposite sex.

 

Characteristics of Sexual Reproduction

  • Mostly biparental
  • Gamete formation takes place
  • Involves fertilisation
  • Involves both meiosis and syngamy
  • Daughter individuals are always different from parents

 

Modes of Asexual Reproduction

 

Fission

  • Fission is the division of the parent body into two or more daughter individuals identical to the parent organism. 
  • It can take place through binary fission, multiple fission and plasmotomy.

 

1. Binary Fission

  • In binary fission, the parent organism divides mitotically into two halves, each half forming an independent daughter individual.
  • The offspring produced are genetically identical to the parent and one another. 
  • Depending on the plane of division, binary fission is of the following types:
    1. Simple Binary Fission: Division occurs through any plane, e.g., Amoeba.
    2. Longitudinal Binary Fission: The plane of division passes along the longitudinal axis of the organism, e.g., Euglena.
    3. Transverse Binary Fission: The plane of division runs along the transverse axis of the organism, e.g., Paramoecium, Planaria.
 
 
 
 
2. Multiple Fission
  • In multiple fission, the parent body divides into many similar daughter individuals.
  • It produces a number of daughter cells from a single parent cell at the same time. 
  • Multiple fission occurs in protozoa such as Amoeba (sporulation) and malarial parasite such as Plasmodium (schizogony).