Reproduction In Organisms Class 12 NCERT Notes In Detail
Reproduction is a biological process wherein younger ones produced are identical to their parents. This phenomenon is significant in the continuity of the species, generation after generations. Typically, reproduction is observed in all living organisms from single-celled entities such as amoeba to multicellular entities of the most advanced forms such as human beings. Reproduction is carried out in two modes depending upon the participation of one or both parents.
Note: As per the revised CBSE curriculum, this chapter has been removed from the syllabus for the 2020-21 academic session.
Necessity Of Reproduction
Reproduction is vital in the process of continuity of species, as a result, sustains a balance in the ecosystem amongst different biotic components precisely. Without reproduction, the life that is thriving now would cease. Reproduction also facilitates evolution due to variations arising from the process of reproduction through the intermingling of species (as seen in sexual reproduction).
Types of Reproduction
In this mode of reproduction, a new offspring is produced by the involvement or participation of single parents only. The produced offsprings are not only identical but are also the exact copies of their parent because in this process a single parent divides itself to reproduce its offspring.
The different types of asexual reproduction are as follows:
- Binary fission
- Vegetative propagation
Examples of asexually reproducing organisms:
Asexual reproduction is common among:
- Single-celled organisms, such as Amoeba, Bacteria, Hydras, yeast cells, etc. In which, Amoeba and Bacteria reproduce by binary fission, Hydras, yeast cells reproduce by budding.
- Few plants species including, Ginger, potatoes, sugarcane, Agave, Bryophyllum, etc. reproduce through vegetative propagation.
- Few animal species including, starfish, black worms, etc. reproduce using fragmentation.
Advantages Of Sexual Reproduction:
- Is carried out by a single individual, hence does not require to find a mate
- The process is faster compared to sexual reproduction
- less energy is invested comparatively
- The whole process is less complicated as it involves only a single individual
- can take place in varied environments
In this mode of reproduction, a new offspring is produced by the participation of two parents of the opposite sex. This type of reproduction is seen in all multicellular organisms including birds, reptiles, dog, cat, cattle’s, elephants, etc. The complete process of sexual reproduction consists of a set of events, including:
Advantages of Sexual Reproduction:
- Involvement of two parents results in the intermingling of genes resulting in the production of a new offspring
- Genetically identical offsprings are produced
- Variations in species increase the chances of survival hence in the evolutionary advancements
Few Important Questions
- What is a bisexual flower?
- What is vegetative propagation?
- Distinguish between Asexual and Sexual Reproduction?
- Distinguish between Gametogenesis and Embryogenesis?
Learn more about reproduction and their types from the topics given below: