Asexual Reproduction in Plants

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INTRODUCTION Reproduction is the creation of is the process by which organisms produce a new organism similar to them. Its of two types:- Sexual Reproduction – the production of a new organism from two parents by making use of their sex cells (or gametes) is called sexual reproduction Asexual Reproduction – the production of a new organism from a single parent without the involvement of sex cells (or gametes) is called asexual reproduction.


TYPES OF ASEXUAL REPRODUCTION Fission Fragmentation Regeneration Budding Vegetative propagation Spore formation


FISSION It is the subdivision of a cell (or body, population, or species) into two or more parts and the regeneration of those parts into separate cells (bodies, populations, or species). It is of two types :- Binary fission – In this type of fission, the cell or organism splits up into two halves. F or ex- many bacteria and protozoa simply split into two halves during cell division. Multiple fission – In this type of fission, the cell splits into many daughter cells at the same time for ex- In plasmodian , which is a malarial parasite, divide into many daughter cells simultaneously.


BINARY FISSION In binary fission, the parent organism splits (or divides) to form two new organisms. When this happens, the parent organism ceases to exist and two new organisms cane into existence. For ex- In amoeba, when the cell has reached its maximum size of growth, then the nucleus and after that the cytoplasm divides into two parts. In this way, one parent amoeba divides to form two smaller amoebae.


MULTIPLE FISSION In multiple fission, the parent organism splits (or divides) to form many new organisms at the same time. Sometimes a cyst or protective wall is formed around the cell. And inside the cyst, the nucleus of cell splits (divides) several times to form many smaller nuclei called daughter nuclei. And then the cytoplasm splits and many new daughter cells are formed from the parent cell within the cyst. For ex- I n plasmodium, which is a malarial parasite, about 1000 daughter cells are produced by the multiple fission of one plasmodium cell.


FRAGMENTATION In fragmentation, the multi-cellular organisms with simple body organisation simply breaks up into smaller pieces upon maturation. These pieces or fragments grow up into new individuals. The splitting may or may not be intentional- it may occur due to man made or natural damage by the environment or predators or the organism may develop specific organs or zones that may be shed or easily broken off. T his method of reproduction is seen in many species such as spyrogyra , lichens, and many other.


REGENERATION Many fully differentiated organisms have the ability to give rise to new individual organisms from their body parts. That is, if the individual is somehow cut or broken up into many pieces, many of these pieces grow into separate individuals. Fro ex- simple animals like planaria can be cut into any number of pieces and each piece grows into a complete organism.


BUDDING In budding, a small part of the body of the parent organism grows out as a ‘bud’ which then detaches and becomes a new organism. For ex- in hydra, a bud develops as an outgrowth due to repeated cell division at one specific site. These buds develop into tiny individuals and when fully mature, detach from the parent body and become new independent individuals.


BUDDING IN YEAST In yeast, first a bud appears on the outside of the cell wall. The nucleus of parent yeast cell then divides into two parts and one part of the nucleus moves into the bud. Ultimately, the bud separates off from the parent yeast cell and forms a new yeast cell. The process is so fast that the first buds start forming their own buds and all of them remain attached to the parent yeast cell forming a chain of yeast cells. After some time, all the yeast cells of the vhain separate from one another and form individual yeast plants.


VEGETATIVE PROPAGATION In vegetative propagation, new plants are obtained from the parts of old plants (like stems, roots and leaves), without the help of any reproductive organs. There are two methods of vegetative propagation:- Natural Vegetative propagation – In this method, the various parts of plants develop on their own. For ex- potato tuber has eye buds which grow into new plant Artificial Vegetative propagation – The process of growing many plants from one plant by man-made methods is called artificial propagation of plants.


The three methods for artificial propagation of plants are :- Cutting – Cutting is the most common artificial vegetative propagation method, where a small part of plant is removed and buried in the moist soil. After a few days the cutting develops into a new plant. For ex- the plants like grapes, sugarcane, banana, etc. can be grown by cutting. Layering – In this method, a branch of the plant is buried under the moist soil and after some time, new roots will develop and it will develop into a new plant. Grafting – In this method, stem cutting from two different plants are joined together in such a way that the two stems join and grow as a single plant. The upper part of plant is known as scion and the lower part is known as stock. THE TYPES of ARTIFICIAL PROPAGATION OF PLANTS


ADVANTAGES OF ARTIFICIAL VEGETATIVE PROPAGATION Some of the important advantages of the artificial vegetative propagation of plants are given below:- The new plants produced will be exactly like the parent plants. The fruit trees grown from cuttings or by grafting start to bear fruits much earlier than the fruit trees grown from seeds. The plants grown usually need less attention in their early years than the plants grown from seeds. Many plants can be grown from just one parent plant. We can also get seedless plants by artificial propagation.


SPORE FORMATION S ometimes the thread-like structures are developed on the bread, these are the hyphae of the bread mould . And on these structures tiny blob like structure is present called sporangia which contains cells or spores, that can eventually develop into new rhizopus individuals. T he spores are covered by thick walls that protect them until they come into contact with another moist surface and can begin to grow.



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