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Asexual Reproduction In Organisms
Reproduction is the fundamental feature to all known life. Each individual organism exists as a result of reproduction. The known method of reproduction are broadly grouped into two main types: sexual and asexual. Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only. There are several types of asexual reproduction, such as, 1. Binary fission, 2. Regeneration, 3. Vegetative Propagation, 4. Budding, and 5. Spore formation.
The process of asexual reproduction in which an organism reproduces by dividing into two individuals is called binary fission. In binary fission, the parent organism is replaced by two daughter organisms because it literally divides into two. A good example of the (seam) is a single cell organism like Paramecium. In this case, the process of reproduction begins with the division of its nucleus into nuclei. This is followed by division of its body into two, each part receiving a nucleus. Finally, two Parameciums are born from a single parent cell.
In case of unicellular organisms, cell division or fission leads to the creation of new individuals. Many different patterns of binary fission have been observed, many baterica and Protozoa simply split into two equal halves during cell division. On the other hand, some single-celled organisms such as the malarial parasite, Plasmodium, divide into many daughter cells simultaneously by multiple fission.
We now move unto another type of asexual reproduction called Regeneration. Simple animals like Planaria can be cut into any number of pieces, and each piece grows into a complete organism. This process is called as regeneration. Regeneration is carried out by specialized cells which proliferate and make large number of cells.
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Asexual reproduction in which new plants are produced from roots, stems, leaves and buds is called Vegetative Propagation. It is called vegetative propagation as the reproduction takes place through the vegetative part of the plants.
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Another example of vegetative propagation comes across in case of the plant Bryophyllum where the buds produced in the notches along its leaf fall on the soil and develop into new plants. Vegetative propagation is also seen in case of Patatoes.
2013-10-14 00:02:54 補充：
You must have seen scars on patatoes, which are also known as eyes. If a potato is cut into small pieces along with the eye, buried in the soil and watered properly, a new potato plant grows from it.
2013-10-14 00:03:30 補充：
There are certain cells that split via the process of budding resulting in a 'mother' and 'daughter' cell. The offspring organism is smaller than the parent. A good example of this is baker's yeast.
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This organisms multiply every few hours, if sufficient nutrients are made available to them. The small projection coming out from yeast cell is called a bud. The bud gradually grows and gets detached from parent cell to form a new yeast cell.
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If this process continues, a large number of yeast cells are produced. Budding also takes place at the multicellular level; in case of animals, budding takes place in hydra. In each hydra, there may be one or more bulges. These bulges are the developing new individuals called buds.
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The new individual develops as outgrowths from a single parent.
You must have seen the slimy green patches in ponds or other stagnant water bodies, these are called algae. When nutrients and water is available, algae grows and multiply rapidly by a process called Fragmentation.
2013-10-14 00:05:46 補充：
An alga breaks into two or more fragments, which grow into new individuals. These process continues and they cover a large area in a short period of time. Fragmentation is a form of asexual reproduction where new organism grows from a fragment of the parent.
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Each fragment develops into a mature, fully grown individual.
The last type of asexual reproduction that we are going to discuss is called spore formation. Spores are asexual reproductive bodies. Each spore is covered by a hard protective coat to withstand unfavorable conditions,
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such as high temperature and low humidity. A spore germinates and develops into a new individual; this process is called spore formation.
You must have noticed the fungi growing on a stale piece of bread back home. The species of Aspergillus, a common fungi,
2013-10-14 00:08:55 補充：
2013-10-15 06:54:24 補充：
No worries, Jim. Many thanks for your help.