Reproduction

Modes of Reproduction

Asexual reproduction
     Mode of reproduction that does not involve the use of gametes or sex cells

Sexual reproduction
     Mode of reproduction that involves the use of gametes or sex cells

Types of asexual reproduction and examples

I. Fission - Type of asexual reproduction involving the division of body into two or more equal parts. Paramecium as example

 II. Budding - Type of asexual reproduction where a new individual arises as an outgrowth (bud) from
its parent, develops organs like those of the parent, and then detaches itself. Hydra as example

 III. Fragmentation - Type of asexual reproduction where the body breaks into two or more parts, with
each fragment capable of becoming a complete individual; in animals, fragmentation is usually
followed by regeneration where the missing parts are produced. For example, a lost arm of the
starfish may be regenerated by mitotic cell divisions.
     - filamentous alga, i.e. Spirogyra or Oedogonium, and a detached starfish arm
growing lost parts as example

 

 IV. Sporulation - Type of asexual reproduction where a new individual forms from an aggregation of
cells surrounded by a resistant capsule or spore, which later on germinates
     - fungus, i.e. Rhizopus, as example

3. Types of union of gametes and examples

I. Isogamy - Fusion of similar gametes which are usually motile
      - Chlamydomonas producing gametes or Spirogyra undergoing conjugation as example

II. Heterogamy - Fusion of dissimilar gametes. In oogamy, a large immotile gamete, the egg is
fertilized by a small motile gamete, the sperm.
     - animal sperm and egg as examples

4. Special terms for sexual reproduction

I. Bisexual reproduction - Type of sexual reproduction involving the union of gametes from two
genetically different parents. Examples are in humans, and papaya among others.

II. Hermaphrodite - An individual with both male and female reproductive tissues. In animals “self
fertilization” is not common. In worms, a hermaphrodite needs a male to donate sperms in order to
fertilize the oocytes in its body. Examples - barnacles; worms

Reproduction and Development in AnimalsReproduction and Development in Plants