REPRODUCTION

REPRODUCTION

 Reproduction is a process by which every living organism produce an organism like their own. 
I.   Types of reproduction :
(a)    Asexual reproduction : In this type of reproduction only one parent organism either mother or father produces new organism.
(b)    Sexual reproduction : In this type of reproduction both parent are involved & produces new organisms.
 

II.    Asexual reproduction in unicellular organism :
1.    Binary fission : During this process, two daughter organisms of equal sizes are formed from one parent by the division of the parent body. This is the most common method of reproduction in algae, fungi and bacteria (fig.).

      Multiple fission: Sonetimes the nucleus divides into many daughter nuclei. The daughter nuclei arrange at the periphery of the parent cell, and a bit of    cytoplasm around each daughter nuclei is present. Nucleus develops an outer                        membrane.   Finally, the multinulceated body divides into many daughter cells. e.g. Blue green algae.

    
(2)    Budding : In this type of reproduction, a small outgrowth appears on the body of the organism. This outgrowth is called a bud. The buds grow and finally detach from the parent body and begin to live as independent organisms. 

(3)    Fragmentation : This takes place in algae like spirogyra and oscillatoria. The filament of the alga breaks into two or more pieces called fragments, and the process is known as fragmentation. Each fragment the grows into a new plant.


(4)    Spore formation : Some lower plants such as ferns, mosses, lichens and fungi reproduce through spore formation under unfavourable conditions. Spores are tiny, microscopic bodies, which are covered by hard protective coats. The protective coats enable them to tide over adverse environmental conditions. When favourable conditions return, each spore gives rise to a new individual. 

ASEXUAL REPRODUCTION IN PLANTS

    When reproduction takes place only from the vegetative parts of plant known as vegetative reproduction.

    (a)    Natural vegetative propagation.
    (b)     Artificial vegetative propagation.

I   Natural vegetative propagation :
    1.   Natural propagation by leaf : Vegetative propagation by leaves can be seen in very few plants like bryophyllum and begonia. In these plants buds are produced on leaf margins. These buds after falling on the ground grow into new                      plants.
    
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