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XII SCIENCE (SYJC)

REPRODUCTION IN LOWER AND HIGHER PLANTS

PART 1 : ASEXUAL REPRODUCTION

DR. ALKAMA FAQIHDEPARTMENT OF BIOLOGY

RIZVI COLLEGEOF ARTS, SCIENCE AND COMMERCE

REPRODUCTION•

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Reproduction is the production of young oneslike parents.Reproduction is an essential process as itleads to continuation of species as well as tomaintain the continuity of life.Each organism has its own particular methodof reproduction.All these methods generally fall into twocategories : i. Asexual reproduction ii. Sexual reproduction.

ASEXUAL REPRODUCTION•

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Asexual reproduction does not involvefusion of two compatible gametes or sexcells.It is the process resulting in the productionof genetically identical progeny from asingle organism and inherits the genes ofthe parent.Such morphologically and geneticallyidentical individuals are called clones.

ASEXUAL REPRODUCTION

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Organisms choose to reproduce asexuallyby different modes or ways:1 - FRAGMENTATION2 - BUDDING3 - SPORE FORMATION4 - BINARY FISSION5 - CONIDIA FORMATION6 - GEMMULES FORMATION


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Fragmentation :Multicellular organisms can break intofragments due to one or the other reasons.e.g. Spirogyra.These fragments grow into newindividuals.


Fragmentation :


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Budding :It is the most common method of asexualreproduction in unicellularYeast(Saccharomyces cerevisiae)Usually it takes place during favourableconditions by producing one or moreoutgrowths (buds).These buds on seperation develop into newindividual.


Budding :


•Spore formation :

In Chlamydomonas asexual reproductionoccurs by flagellated, motile zoosporeswhich can grow independently into newindividuals.


Spore formation :


•Binary Fission :

In Amoeba, Paramoecium, etc. asexualreproduction occurs by dividing theunicellular single body into two newindividuals.


Binary Fission :


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Conidia formation :A chain of non motile spores in fungi isknown as conidia.Penicillium, Aspergillus, etc. reproduce byconidia.


Conidia formation :


•Gemmules formation :

Gemmules are internal buds found insponges and are involved in asexualreproduction. It is an asexually reproducedmass of cells, that is capable ofdeveloping into a new organism i.e., anadult sponge.


Gemmules formation :


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Vegetative Reproduction :Plants reproduce asexually through theirvegetative parts.Hence, the new plants formed aregenetically identical to their parents.There are also few methods which wouldnot occur naturally in the plants.Agriculture and horticulture exploitvegetative reproduction in order to multiplyfresh stocks of plants.


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Artificial methods are used to propagatedesired varieties according to humanrequirements.Vegetative Reproduction :

The various methods are as follows :1 - Cutting2 - Grafting3 - Tissue Culture


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Vegetative Reproduction :Cutting :

The small piece of any vegetative part of aplant having one or more buds is used forpropagation viz.Stem cutting - e.g. Rose, Bougainvillea;leaf cutting - e.g. Sansvieria;root cutting e.g. Blackberry.


Vegetative Reproduction :Cutting :


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Vegetative Reproduction :Grafting :

Here parts of two plants are joined in sucha way that they grow as one plant.In this method, part of the stem containingmore than one bud (Scion) is joined onto arooted plant called stock, is called grafting.Whereas budding is also called bud graftingin which only one bud is joined on the stock,e.g. Apple, Pear, Rose, etc.


Vegetative Reproduction :Grafting :


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Vegetative Reproduction :Tissue culture :

It is a method by which a small amount ofplant tissue is carefully grown to givemany plantlets.Micropropagation method is also usednow a days.


Vegetative Reproduction :Tissue culture :

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