Reproduction

Back to: O level Biology NOTES Uganda syllabus

Reproduction is the process by which organisms multiply to increase in number. This is important in maintaining the life of organisms from one generation to another.
Types of reproduction
There are two types of reproduction.

  1. Asexual reproduction
  2. Sexual reproduction.
    ASEXUAL REPRODUCTION
    This is a type of reproduction, which does not involve fusion of gametes, and therefore only one individual is involved. This type of reproduction takes several forms, which include the following.
    a) Budding.
    This is a mode of asexual reproduction in which an organism develops an outgrowth (bud), which detaches its self from the parent organism and starts to grow as a self-reliant organism. It is common in yeast and hydra.
    b) Spore formation
    This is a mode of asexual reproduction, which involves production of spores. Spores are microscopic structures, which can be dispersed and have the ability to germinate into a new organism under favorable conditions. This mode of reproduction is common in fungi and some bacteria.
    c) Fragmentation
    This is a mode of asexual reproduction where an organism breaks into many small parts (fragments) and each is able to grow into a new individual. It is common in tapeworms and spirogyra.
    d) Binary fission
    This is a mode of asexual reproduction where a single celled organism divides up into two parts, which start to grow as separate individuals. It is common in amoeba and other protozoans

Question:
Describe the process of asexual reproduction in;
i) Amoeba
ii) Rhizopus
iii) Yeast
iv) Spirogyra
e) Multiple fission
This is a mode of asexual reproduction where a single celled organism divides into many parts, which grow into separate individuals. This occurs in plasmodium.
f) Vegetative reproduction
This is a mode of reproduction in plants where part of the plant other than the seeds develops into a new individual. This normally takes many forms, which include rhizomes, bulbs, corms, suckers, stolons, runners etc

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Advantages of vegetative reproduction

  • New plants resemble the parent plant and any good quality in the parent is retained.
  • The growth of the new plant is rapid.
  • The reproductive organ stores plenty of food which the new plant uses.
  • It does not involve processes like pollination, fertilization and dispersal agents are not required.
  • Large areas can be covered in relatively little time.
  • It involved only one individual.


Disadvantages

  • Since new plant grows on its parent, it can lead to crowding.
  • Shortage of water and mineral salts is likely to occur due to competition.
  • Diseases of the parent plant can be transmitted to the young ones.
  • If the parent plant has poor characters, they can be maintained by the young