Rajasthan Board RBSE Class 10 Science Important Questions Chapter 8 How do Organisms Reproduce? Important Questions and Answers.
RBSE Class 10 Science Chapter 8 Important Questions How do Organisms Reproduce?
Objective Type Questions
In the flower the middle part of carpel is called –
(c) anther lobe
How much time does a foetus take to develop in mother’s body?
(a) 100 days
(b) 200 days
(c) 150 days
(d) 270 days
(d) 270 days
If egg cell is not fertilised how many days does it take for its survival?
(a) one day
(b) two days
(c) three days
(d) four days
(a) one day
In which prostate and seminal vesicle put their secretion?
(a) vas deferens
(d) none of the above
(a) vas deferens
The two oviducts unit to form an elastic bag like structure is known as –
In ladies copper – T is placed –
(a) in ovary
(b) in uterus
(c) in vagina
(b) in uterus
By which the vegetative reproduction takes place in the Bryophyllum plant?
(a) bud of leaf
(b) vegetaive bud
(a) bud of leaf
Who makes the association between mother and embryo, in which functional exchange takes place –
(b) vas deferens
Very Short Answer Type Questions
Give the importance of DNA.
The chromosomes in the nucleus of a cell contain information for inheritance of features from parents to next generation in the form of DNA molecule.
Name the reproductive method used to grow plants that have lost the capacity to produce seeds.
Such plants grow through vegetative propagation. Example – orange, rose, jasmine.
Question 3 .
Name the structures that provide nutrition from the mother’s blood to the foetus.
What type of fission is found in Plasmodium?
Multiple fission is present.
Write the name of reproductive method in Amoeba.
Reproduction in Amoeba takes place by binary fision.
What is the difference between the fission of Amoeba and Leishmania ?
In Amoeba, the splitting of the two cells during division can take place in any plane whereas, in Leishmania, binary fission occur in a definite orientation.
Write full name of AIDS.
AIDS = Acquired Immuno Defeciency Syndrome.
What types of reproductive method is used in spirogyra?
By fragmentation method.
Write the name of question marked parts in the given diagram and which method of reproduction is showing?
(ii) Bud. This is the asexual reproduction method.
What is regeneration?
If the individual is somehow cut or broken up into many pieces, many of these pieces grow into separate individuals. This is known as regeneration.
Name the techniques of vegetative propagation that are used in agriculture.
Layering and grafting are such techniques of vegetative propagation that are used in agriculture.
What is tissue culture ?
In tissue culture, new plants are grown by removing tissue or separating cells from the growing tip of a plant.
What would have happened if the DNA copying mechanisms were to be less accurate?
If the DNA copying mechanisms were to be less accurate, many of the resultant DNA copies would not be able to work with the cellular appratus, and would die.
Where does the reproductive parts of angiosperms located?
The reproduction parts of angiosperms are located in the flower.
Inspect the figure and write the name of question marked parts.
Write the names of directed A, B, C and D in the figure.
(A) Pollen grain
(C) Pollen tube
Where does fertilisation take place in ladies?
In fallopian tube.
What is reproduction? How many types are there of it?
The production of offspring by organisms is called reproduction. It is mainly of two types –
- Asexual reproduction.
- Sexual reproduction.
Write the full name of DNA.
Full name of DNA is Deoxyribonucleic acid.
Write the function of thick wall found around the spore.
The thick wall found around the spore protects the spore in unfavourable conditions.
What is called the motile reproductive cell?
Motile reproductive cell is called male gamete (sperm).
When in a flower stamen or pistil only one reproductive organ is present, what are called such flowers?
When only one reproductive organ i.e. stamen or pistil in present in the flower, such flowers are called unisexual.
What is the position of female reproductive organ i.e. pistil in the flower.
Female reproductive organ (pistil) is present in the centre of the flower.
In which part of pistil are the. ovules situated?
Ovules are situated in the ovary part of pistil.
In which form does an ovule convert after fertilization?
After fertilization an ovule is converts into seed.
What type of reproduction is found in human?
Sexual reproduction is found in human.
What is puberty?
The period during addescence in which the reproductive tissues begin to mature is called puberty.
What are sperms?
The sperm are tiny bodies that consist of mainly genetic material and a long tail that helps them to move towards the female germ – cell.
What is the location of scrotum in human?
In human scrotum is situated outside the abdominal cavity.
Write the name of hormone which controls the puberty characters in boys.
Testosterone hormone controls the puberty characters in boys.
Why in males urethra is called common passage?
Because in male urethra serves two 1 functions. It carries urine as well as semen.
Write the name of that structure, whose structure is a disc liks and which is embedded in the wall of uterus.
The placenta is a disc like structure and it is embedded in the wall of uterus.
What happens by rhythmic contractions of the muscles of uterus?
The child is bom as a result of rhythmic contraction of the muscles in the uterus.
How many eggs are released in every month by ovary?
Ovary releases one egg in every month.
What are sexually transmitted diseases?
Diseases which develop by sexual contact are called sexually transmitted diseases.
Give examples of bacterial and viral generated sexually transmitted diseases (STD).
1. Bacterial generated sexually transmitted disease:
2. Viral generated sexually transmitted disease:
- HIV – AIDS.
How the size of population is determined ?
The rates of birth and death in a given population will determine its size.
Write the use of tissue culture.
The use of this technique is generally done in the culture of ornamental plants.
Short Answer Type Questions
What happens when the egg is not fertilised?
If the egg is not fertilized, it lives for about one day, since the ovary release one egg every month, the uterus also prepares itself every month to receive a fertilized egg. Thus its lining becomes thick and spongy. This would be required for nourshing the embryo if fertilization had taken place. Now, however, this lining is not needed any longer. So, the lining slowly breaks and comes out through the vagina as blood and mucous. This cycle take place roughly every month as is known as menstruation. It usually lasts for about two to eight days.
Why it is necessary to have a organised cellular structure along with DNA copying?
A basic event in reproduction is the creation of a DNA copy. Cells use chemical reaction to build copies of their DNA. This creats two copies of the DNA in a reproducing cell, and they will need to be separated from each other. However keeping one copy of DNA in the original cell and simply pushing the other one out would not work, because the copy pushed out would not have any organised cellular structure for maintaining life processes.
Therefore, DNA copying is accompanied by the creation of an additional cellular apparatus, and then’ the DNA copies separate, each with its own cellular apparatus. Effectively, a cell divides to give rise to two cells.
Give one example of each of the following types of reproduction –
- Spore formation
- Multiple – fission
- vegetative propogation.
Type of asexual reproduction Example
- Binary – fission – Amoeba
- Budding – Hydra
- Spore formation – Rhizopus
- Regeneration – Planaria
- Multiple-fission – Malaria parasite
- Vegetative propogation – Rose
What do you mean by reproduction? Write basic characters of sexual reproduction.
Reproduction – The process by which organism produces alike offspring, is called reproduction.
Basic characters of sexual reproduction:
- Offspring is produced by fusion of egg and sperm. These structures are called, sexual cells or gametes.
- After fertilization, male and female gamete combined to form zygote and after development it makes a mature organism.
- Its result in the fusion of genetic material of two parents.
Why it is important to have mature reproductive organs and breasts in mothers during reproduction?
In mammals such as humans, the baby is carried in the mother’s body for a long period, and will be breast-fed later. The female reproductive organs and breasts will need to mature to accommodate these possibilities.
Describe with diagram the binary – fission in amoeba.
This is a common and simple method of asexual reproduction, which takes place in a favouarable condition.
Binary fission in Amoeba:
In this method the body of amoeba by cell division is divided into two equal parts which form two offsprings (daughter amoeba). Daughter amoeba after 24 hrs it can repeate this process. The volume of each daughter amoeba is half to parent amoeba.
What is uni – sexual and bi – sexual flower? Give one example of each.
Uni – sexual flower: When in flower out of stamen or pistil only one reproductive organ is present, it is called uni – sexual flower.
Watermelon and papaya.
Bi – sexual flower: When stamen and pistil both are present in a flower, it is called bi – sexual flower.
Mustard and China rose.
By which technique can many plants be grown from one plant in disease free conditions? Explain.
In tissue culture, new plants are grown by removing tissue or separating cells from the growing tip of a plant. The cells are then placed in an artificial medium where they divide rapidly to form a small group of cells or callus. The callus is transferred to another medium containing hormones for growth and differentiation. The plantlets are then placed in the soil so that they can grow into mature plants. Using tissue culture, many plants can be grown from one parent in disease-free conditions. This technique is commonly used for ornamental plants.
Why are testes outside the abdominal cavity? Explain.
In human, testes are located outside the abdominal cavity because sperms require a lower temperature than the normal body temperature. Testes have temperature about 3°C lower than the normal body temperature.
How variation is important in maintaining the survival of species?
Populations of organisms fill well – defined place, or niches, in the ecosystem, using their ability to reproduce. The consistency of DNA coping during reproduction is important for the maintenance of body design features that allow the organisms to use that particular niche. Reproduction therefore linked to the stability of populations of species.
However, niches can change because of reason beyond the control of the organisms. Temperatures on earth can go up or down, water levels can vary, or there could be meteorite hits to think of a few examples. If population of reproducing organism were suited to a particular niche and if the niches were drastically altered, the population could be wiped out. However, if some variations were to be present in a few individuals in these populations, there would be some chance for them to survive. Variation in thus useful for the survival of species over time.
Write short note on spore formation.
Even in many simple multi – cellular organisms, specific reproductive parts can be identified. Example – On erect hyphae there are rounded structure present, which are called sporangia. They take part in reproduction. The blobs are sparangia, which contain cells or spores, that can eventually develop into new Rhizopus individuals (Fig.) The spores are covered by thick walls that protect them until they come into contact with another moist surface and can begin to grow.
Spore formation in Rhizopus
How is placenta helpful in embryo development?
Placenta is helpful in embryo development in the following ways:
- Embryo gets the nutrient material from female by placenta.
- Placenta is helpful in exchange of O2 and CO2 between embryo and female.
- Progesteron secreted by placenta is helpful to maintain the foetus in total pregnant period.
- The developing embryo will also generate waste substances which can be removed by transferring them into the mother’s blood through the placenta.
In adult after the removal of vas deferens will the rubber tube is put in place of this, what effect will be? Explain.
If in adult after removal of vas deferens the rubber tube is put in place of this, the transport of sperms will not take place because cells of vas deferens secret special liquid material, which makes the smooth passage for locomotion of sperms. The muscles of vas deferens wall develop a wave motion by which sperms go forward. So in rubber tube there will be no locomotion.
What is puberty? Explain.
Puberty: In human (male and female) the immature reproductive organs become mature to develop the reproductive capacity, is called puberty. Comparatively in females puberty starts first. In human male puberty starts at the age of 14 – 16, at this age there is production of sperms and activation of testes start. In female it starts by growth of mammary gland and menustration at the age of 12 – 14 years.
If the fallopian ‘tube of the female is tied by a thread, which activity will be affected and why?
In female on tying the fallopian tube by thread the egg will not reach to uterus. As a result the sperms will not fuse i.e., fertilization process will not take place. To fie the fallopian tube or to cut it in surgery, is called tubectomy.
Why sexual mode of reproduction developed?
The creation of two new cells from one involves copying of the DNA as well as of the cellular apparatus. The DNA copying mechanism cannot be absolutely accurate, and the resultant errors are a source of variations in populations of organisms. Every individual organisms can not be protected by variations, but in a population, variations are useful for ensuring the survival of the species. It would, therefore, make sense if organisms come up with reproductive modes that allowed more and more variation to be generated.
Write difference in sexual and asexual reproduction.
The following are the differences between the sexual and asexual reproduction –
|Sexual reproduction||Asexual reproduction|
|In this process two animals take part.||It takes place only in one animal.|
|Gametes (sperm and eggs) are formed.||There is no formation of gametes.|
|With mitosis there is meiosis division also takes place.||Only mitosis division|
|There is gametic fusion.||No gametic fusion occurs.|
|The offspring developed by this process have genetically variations.||Offspring produced are genetically identical to parents.|
Why meiosis developed?
Why and how we can prevent the doubling of the DNA is next generation during sexual reproduction?
If each new generation during sexual reproduction is to be the combination of the DNA copies from two pre – existing individuals, then each new generation will end up having twice the amount of DNA that the previous generation had. This is likely to mass up the control of the cellular apparatus by the DNA. We have seen eailier that a organisms become more complex, the specialisation of tissue increases.
One solution that many multicellular organisms have found for the problem mentioned above is to have special lineages of cells in specialised organ in which only half the number of chrome – somes and half the amount of DNA as compared to the non-celled meiosis. Thus when these germ – cells from two individuals combine during sexual reproduction to form a new individual, it results in re – establisment of the number of chromosomes and the DNA content in the new generation.
Write the advantages and disadvantages of cross-pollination.
Advantage by cross – pollination:
In cross – pollinated flowers the male gamete of one plant and egg of other plant of same species take part in fertilisation. Embryo develop from fertilised egg and seed from ovule. On germination of seed embryo form the new offspring (plant). This offspring consists of new characters and its seeds are more viable.
Disadvantages by cross-pollination:
pend on external measure like insect, air, water, so cross – pollination is indefinite. For these measures necessary adaptation (like – colour, odour, nectar) and energy spent by plant. In air pollination most of the pollen grains go waste, even than the event of pollination is not definite. In air pollination pollen grain of a flower reaches the flower of other plant of same species is only a chance.
What is self-pollination? What are its advantages?
Self-pollination – Transfer of pollen grain of a flower on the stigma of flower of the same plant is called self – pollination.
Advantages of self-pollination – In self – pollinated flowers self-pollination is completely a definite process. To reach upto the stigma pollen grain is not dependent on different measures. Pollen grains do not go waste. So the small quantity of pollen grains is sufficient. There is no expenditure on additional liquid and energy for special adaptation (like – flower structure, colour and nectar etc.) to the plant.
Write the changes that are common in both boys and girls during adolescence.
The changes that are common in both boys and girls during adolescence are as follows :
- Thick hair growing in new parts of the body such as armpits and the genital area between the thighs, which can also become darker in colour.
- Thinner hair can also appear in legs and arms, as well as on face.
- The skin frequently become oily and might begin to develop pimples.
- They may be conscious and aware of both, their own bodies and those of others in new ways.
Write the change takes plate in human male at the time of puberty.
The change takes place in human male at the time of puberty:
- Penis, scrotum, prostate gland and seminal vesicle become larger.
- Testes become larger and spermatogenesis process starts.
- Voice begins to crack.
- Hairs grow on face, chest, armpits, genital area and between the thighs.
- Voice becomes lower, deep and hoarse.
- Increase in secretion of hormone testosterone, FSH, LH etc.
- Psychological attraction towards female.
Point out any five differences in spermatogenesis and oogenesis.
Differences in spermatogenesis and oogenesis –
|1. This process takes place in testes.||It takes place in ovaries.|
|2. Spermatogenesis process is continued till life in the animal.||This process stops after a definite age.|
|3. In this process all spermatogoni a cells form the sperms.||Only one oogonial cell|
|4. In this process first and second maturation phase is similar and in the result four similar sperms are formed. All these four act as independent reproductive unit.||oogonium. Many other oogonial cells are destroyed in growth phase.|
|5. Sperms are motile and yolkless.||Both maturation phase is different, due to this one large ovum cell and three small polar bodies are formed. In this process only ovum in the independent reproductive units. Ovum is non-motile and containing yolk.|
Why are there differences in the size of the male and female gametes of most sexually reproducing organisms?
Why is the female gamete larger than the male gametes?
If the zygote is to grow and develop into an organism which has highly specialised tissues and organs, then it has to have sufficient stores of energy for doing this. In very simple organisms, it is seen that the two germ-cells are not very different from one another, or may even be similar. But as the body designs become more complex, the germ-cells also specialise. One germ – cell is large and contains the food- stores while the other smaller and likely to be motile. Conventionally, the motile germ – cell is called the male gamete and the germ – cell containing the stored food is called the female gamete.
What are the benefits to the plants from the formation of seeds?
- The seed contains an embryo and a seed is formed by developing a hard covering from the ovule, so the embryo is safe in the seed.
- Food is stored in the seed which help the embryo to get nutrition.
- Seed is also helpful in scattering of plant species.
- The seed germinates under appropriate conditions and develop into a new plant.
What is carpel? Describe its structure.
In an angio – spermic flower the female reproductive organ is called gynoecium. Each member of gynoecium is known as carpel. Each carpel is a megasprophyll.
A carpel is having three parts – Stigma, style and ovary. Lowest part of the ovary is swollen, from which a tube like structure style develops and top of the style is called stigma. Inside the ovary numerous small eggs like structures are present, which is called ovule or megasporangium. Each ovule with the help of a stalk like structure is attached to inner wall of ovary on cushion shaped or placenta. The stalk of the ovule is called funicle.
Write the difference in sperm and ovum of human.
Difference in sperm and ovum –
|Human sperm.||Human ovum.|
|It is called male garnets.||It is called female gamete.|
|It is formed inside the testes.||It is formed inside ovary.|
|They are long and each consists of a tail||It is rounded and tail is absent.|
|They are motile.||It is non – motile.|
|In size sperms are smaller than ovum.||The egg is larger than a sperm.|
|Production of sperms is more in number.||Production of only one ovum occurs in each month in a human.|
Explain asexul reproduction in Leishmania ?
Some unicellular organisms show somewhat more organisation of their bodies. such as in Leishmiania, which cause kala – azar. It have a whip like structure at one end of the cell. In such organisms, binary fission occurs in a definite orientation which results in formation of two new individuals.
Explain multiple fission in Plasmodium.
Some single – celled organisms, such as the malarial parasite, Plasmodium, divide into many daughter cells simultaneously by muliple fission.
Multiple fission in Plasmodium
What are the basic aspects of asexual reproduction?
The basic aspects of asexual reproduction are –
- In this process only one organisms is involved i.e., male and female are not involved.
- Asexual reproduction essentially involve mitotic cell division or amitotic cell division.
- Developed population is genetically identical to the parent cell.
- It is a rapid method for increasing the number.
Why are the signs of sexual maturity in the human body reflected in adolescence ?
Specialised cell type in multicellular bodies are needed to carry out specialised functions. The creation of germ cells to participate in sexual reproduction is another specialised function and plants also develop, special cell and tissue types to create them. Human beings also develop special tissues for this purpose. However, while the body of the individual organism is growing to its adult size, the resources of the body are mainly directed at achieving tins growth.
While that is happening, the maturation of the reproductive tissue is not likely to be a major priority. Thus as the rate of general body growth begins to slow down, reproductive tissue begin to mature, hence the signs of sexual maturity is reflected in adolescence.
Write the functions of a flower.
Following are the functions of a flower –
- To hold the male and female reproductive organ.
- Developing the male and female gametophyte in reproductive . organs and form the male and female gamete.
- Fusion of gametes of opposite sex or fertilisation process.
- Formation of fruits and seeds.
How vegetative propagation takes place in Bryophyllum. Explain.
Leaf of Bryophyllum with buds
There are many plants in which parts like the roof, stem and leaves develop into new plants under appropriate conditions. Similarly buds produced in the notches along the leaf margin of Bryophyllum fall on the soil and develop into new plants.
Why multicellular organisms need more complex method of reproduction?
Why multicellular organisms do not divide cell by cell as easily as in Amoeba ?
The reason is that many multi – cellular organisms, as we have seen, are not simply a random collection of cells. Specialised cells are organised as tissues, and tissues are organised into organs. Which then have to be placed at definite position in the body. In such a carefully organised situation, cell by cell division would be impractical. Multi-cellular organisms, therefore, need to use more complex ways of reproduction.
Essay Type Questions
Draw a labelled diagram of longitudinal section of flower and describe the speciality and function of its different part.
Diagram of Longitudinal section of a flower –
Longitudinal section of flower
Description of function and speciality of different parts of flower is as –
|1. Pedicel or stalk of flower||It is a stalk like structure.||It joins the flower to the plant.|
|2. Thalamus||It is usually flat or swollen.||It provide the base to the other parts of flower.|
|3. Calyx||Outermost part of the flower is green in colour.||In the bud stage of flower it protects the internal organs.|
|4. Corolla||Inner part of calyx is called corolla. Each member of it is called petal. Its colour is different in different flowers.||It attracts the insects and birds for pollination.|
|5. Stamen||It is the male reproductive part of flower. Mainly it consists of two parts – anther and filament. Anthers are united by connective. Pollen grains are present inside the anther which undergoes in pollination.||There is the formation of pollen grains in anther.|
|6. Pistil||It is the female reproductive part of the flower. It consists three parts – stigma, style and ovary.||Fruit from ovary and seed from ovule are formed.|
Do organisms create exact copies of themselves ? Explain with example.
How variation arise in children as compared to parent? Explain.
Organisms look similar because their body designs are similar, if body designs are to be similar, the blueprints of these designs should be similar. Thus, reproduction at its most basic level will involve making copies of the blueprints of body designs. The chromosomes in the nucleus of a cell contain information for inheritance of features from parents to next generation in the form of DNA molecules. The DNA in the cell nucleus is the information source for making proteins. If the information is changed, different proteins will be made. Different proteins will eventually lead to altered body desings.
Therefore, a basic event in reproduction in the creation of a DNA copy. Cells use chemical reactions to build copies of their DNA. But no bio – chemical reaction is absolutely reliable. Therefore, it is only to be expected that the process of copying DNA will have some variation each time. As a result, the DNA copies generated will be similar, but may not be identical to the original. Some of these variations might be so drastic that the new DNA copy cannot work with the cellular apparatus it inherits.
Such a new born cell will simply die. On the other hand, there could still be many other variations in the DNA copies that would not lead to such a drastic outcome. Thus, the surviving cells are similar to, but subtly different from each other. This inbuilt tendency for variation during reproduction is the baiss of evolution.
What is germination? With the help of diagram describe in short the structure of gram seed.
The seed contains the future plant or embryo which develops into a seedling under appropriate conditions. This process is known as germination.
Structure of gram seed:
To know the structure soak a few seeds of gram and keep them overnight. After this, cover the seeds with a wet cloth and leave them for a day. Make sure that the seeds do not become dry.
Now remove the outer layer of these wet seeds – this layer is called seed coat. After removing the seed coat two leaves like structures are present, called cotyledon. Cotyledon stores food material. In between these cotyledon embryo in situated.
At the time of seed germination root from radicle and shoot (stem) from plumule develops. See in figure. Food is stored in cotyledon which provides the nutrition to the embryo at the time of germination, those seeds consists of two cotyledon, which are called dicotyledons; so this seed in dicotyledoa
Describe the method of fertilisation, seed and fruit in flowering plant. Show with the help of diagram germinated pollen grain on stigma.
After the pollen lands on a suitable stigma, male gamete has to reach the female gamete which is situated in the ovary. For this, a tube grows out of the pollen grain and travels through the style to reach the ovary. Inside the ovary the egg cell is present in embryo sac. The tip of the pollen tube bursts and due to this male gametes are liberated. One male gamete fuses with egg to form zygote. This fusion is called fertilisation. The second male gamete fuse with diploid secondary nucleus and make endosperm nucleus.
After fertilisation, the zygote divides several times to form an embryo within the ovule. The ovule develops a tough coat and is gradually converted into a seed. The ovary grows rapidly and ripens to form a fruit. Meanwhile, the petals, sepals, stamens, style and stigma may shrivel and fall off.
The seed contains the future plant or embryo which develops into a seedling under appropriate conditions. This process is known as germination.
Germination of pollen on stigma
Draw diagram and describe the male reproductive system in human.
Male reproductive system – The male reproductive system consists of portions which produce the germ-cells (sperms) and other portions that deliver the germ-cells to the site of fertilisation. The formation of germ cells or sperms takes place in the testes. These are located outside the abdominal cavity in scrotum because sperm formation requires a lower temperature than the normal body temperature. In addition to regulating the formation of sperms, testosterone brings about changes in appreance seen in boys at the time of puberty.
The sperms formed are delivered through the vas deferens which unites with a tube coming from the urinary bladder. The urethra thus forms a common passage for both the sperms and urine. Along the path of the vas deferens, glands like the postrate and the seminal vesicles add their secretions so that the sperms are now in a fluid which makes their transport easier and this fluid also provides nutrition. The sperms are tiny bodies that consists of mainly genetic material and a long tail that helps them to move towards the female germ-cell.
Human-male reproductive system
Describe with the help of labelled diagram the female reproductive system in human.
The female germ – cells or eggs are made in the ovaries. They are also responsible for the production of some hormones. When a girl is born, the ovaries already contain thousands of immature eggs. On reaching puberty, some of these start maturing. One egg is produced every month by one of the ovaries. The egg is carried from the ovary to the womb through a thin oviduct or fallopian tube. The two oviducts unite into an elastic bag-like structure known as the uterus. The uterus opens into the vagina through the cervis.
Human-female reproductive system
What is asexual reproduction ? Describe its main types.
The mode of reproduction in which new generation formed is without gamete fertilization and is only from a single individual. This is called asexual reproduction.
There are many types of asexual reproduction. Like:
(1) Fission: For unicellular organisms, cell division, or fission, leads to the creation of new individuals. Many bacterial and protozoa simply split into two equal haves during cell division. In organisms such as Amoeba, the splitting of the two cells during division cart take place in any plane.
(2) Fragmentation: In multi-cellular organisms with relatively simple body organisation, fragmentation is found. In this the organism simply breaks up into smaller pieces upon maturation. These pieces or fragments grow into new individuals. Example – Spirogyra.
(3) Reproduction by 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. For example, simple animals like Hydra and Planaria can be cut into any number of pieces and each pieces grows into a complete organisms. This is known as regeneration. Regeneration is carried out by specialised cells.
These cells proliferate and make large numbers of cells. From this mass of cells, different cells undergo changes to become various cell types and tissues. These changes take place in an organised sequence referred to as development. However, regneration is not the same as reproduction, since most organisms would not normally depend on being cut up to be able to reproduce.
Regneration in Planaria
(4) Reproduction by budding: In this type of reproduction on the body of the adult an outgrowth is developed which is called bud. This bud after complete growth separates from parent. This type of reproduction is called budding.
Organisms such as Hydra use regenerative cells for reproduction in the process of budding. In Hydra, a bud develops as an outgrowth due to repeated cell division at one specific site (Fig.). These buds develop into tiny individuals and when fully mature, detach from the parent body and become new independent individuals.
Budding in Hydra
(5) Reproduction by vegetative propogation:
There are many plants in which parts like the root, stem and leaves develop into new plants under appropriate conditions. Mostely single plants use this capacity in mode for reproduction. As – Rhizome of ginger, bulb of potato, leaf bud of Bryophyllum etc. This property of vegetative propogation is used in methods such as layering, culm or grafting to grow many plants like rose, grapes, sugarcane etc.