- 1 Comment
- Asexual reproduction
Reproduction is the production of young
ones like parents. Reproduction is an essential
process as it leads to continuation of species as
well as to maintain the continuity of life. Each
organism has its own particular method of
reproduction. All these methods generally fall
into two categories :
i. Asexual reproduction
ii. Sexual reproduction.
Now we are Looking for Asexual reproduction
Asexual reproduction does not involve
fusion of two compatible gametes or sex cells.
It is the process resulting in the production of
genetically identical progeny from a single
organism and inherits the genes of the parent.
Such morphologically and genetically identical
individuals are called clones. Organisms
choose to reproduce asexually by different
modes or ways:
i. Fragmentation: Multicellular organisms
can break into fragments due to one or
the other reasons.
ii. Budding : It is the most common method
of asexual reproduction in unicellular
Yeast. Usually it takes place during
favourable conditions by producing one
or more outgrowths (buds). These buds on
seperation develop into new individual.
iii. Spore formation : In Chlamydomonas
asexual reproduction occurs by flagellated,
motile zoospores which can grow
independently into new individuals.
Zoospores in Chlamydomonas
Other methods of asexual reproduction
include – Binary fission which occurs in
Amoeba, Paramoecium; Conidia formation
in Penicillium and Gemmules formation in
Plants reproduce asexually through their
vegetative parts. Hence, the new plants formed
are genetically identical to their parents.
There are also few methods which would
not occur naturally in the plants. Agriculture
and horticulture exploit vegetative reproduction
in order to multiply fresh stocks of plants.
Artificial methods are used to propagate desired
varieties according to human requirements.
The various methods are as follows :
a. Cutting :
The small piece of any vegetative part
of a plant having one or more buds is used
for propagation viz. Stem cutting – e.g. Rose,
Bougainvillea; leaf cutting – e.g. Sansvieria;
root cutting e.g. Blackberry.
b. Grafting :
Here parts of two plants are joined in
such a way that they grow as one plant. In
this method, part of the stem containing more
than one bud (Scion) is joined onto a rooted
plant called stock, is called grafting. Whereas
budding is also called bud grafting in which
only one bud is joined on the stock.
c. Tissue culture : It is a method by
which a small amount of plant tissue is carefully grown to give many plant lets.
Micropropagation method is also used now.