how do organisms reproduce class 10 notes

How do organisms reproduce

The production of new organisms from the existing organisms of the same species is known as reproduction. In most simple words we can say that reproduction is the creation of new living things from the existing living things. Actually one of the most important characteristics of living organisms is there ability to reproduce more members of their species. Reproduction is essential for the survival of a species on this earth. So, living organisms produce more organisms of their kind to maintain the life of their species on this earth.

The processes of reproduction insurea continuity of life on earth. For example, human beings reproduce by giving birth to babies. This babies grow and ultimately become adults full stop so when the old parents die their sons and daughters keep living on this earth.

Reproduction gives rise to more organisms with the same basic characteristic as their parents. Human beings always produce human babies; cats always produce kittens; and sunflower seeds always produce and flower plants. The living organisms cannot reproduce due to certain reasons, then the organisms of this basis will gradually die out and disappear from this earth one day.

Types of reproduction

There are many different ways in which new organisms are produced from their parents. Some organisms like amoeba just split into two parts to produce new amoebae.

There are two main methods of reproduction in living organisms:

1. Asexual reproduction

2. Sexual reproduction

How do organisms reproduce asexually

In asexual reproduction the offspring arises from a single parent. The reproduction of a new organism from a single parent without the involvement of sex cell is called asexual reproduction. It is called asexualreproduction because it does not use special cell called sex sales for producing a new organism. Some of the examples of a sexual reproduction are: binary fission in amoeba; budding in hydra; S4 formation in rhizopus; regeneration in planaria; fragmentation in spirogyra and vegetative propagation in flowering plants.

 How do organisms reproduce sexually

 In sexual reproduction, the offspring arises from two parents of different sexes: a male sex and a female sex full stop the male parent contains male sex cell or male gametes and the female parent contains female sex cell or female gametes. The production of a new organism from two parents by making use of their gammates is called sexual reproduction. In sexual reproduction, the sex cell of one parent fuse with the sex cell of the other parent to form a new cell called zygote. This Jai got them grows and develops to form a new organism.Thus, in sexual reproduction to parents are needed to produce a new organism. The two parents which are involved in sexual reproduction are called male and female. The humans, fish, frogs, hens, cats, dogs, cows, horses, bears rabbits lions and tigers all reproduce by the method of sexual reproduction. Most of the flowering plants also reproduced by sexual reproduction. The basic difference between asexual reproduction and sexual reproduction is that only one parent is needed in a sexual reproduction where has two parents are needed in sexual reproduction. And other difference is that no sex cells are involved in a sexual reproduction.

Asexual reproduction

In the asexual reproduction method certain body cells of the parent organism undergo repeated myosis cell divisions to form two or more new organisms of the same kind full stop a sexual reproduction takes place by 6 different methods. These are: 

1. Fission

2. Budding

3. Spore formation

4. Regeneration

5. Fragmentation

6. Vegetative propagation

1.Fission

Many single cell organism like protozo and bacteria just split or break into two identical halves during cell division, leading to the creation of new organisms. This is called fission. in biology, Fission is the process of reproduction in unicellular organisms such as protozoa like amiba paramesium leishmania and many bacteria. In this process a unicellular organism split to form two or more new organisms.

• Binary Fission:- binary fission is an a sexual method of reproduction of organism full stop in binary fission the parent organism split to form to new organisms. When this happens the parent organism cease to exist and two new organisms come into existence. 

Amiba reproduced by binary fission by dividing its body into two parts. This happens as follow:- when the amoeba cell has reached it's maximum size of growth, then first the nucleus of amoeba lenthens and divides into two parts. After that the cytoplasm of amoeba divides into two parts one part around each nucleus full stop in this way one parent amoeba divides to form to smaller amoeba. The daughter amoeba produce here go to their full size by eating food and then divide again to produce four amoebae. In the unicellular organisms such as amiba the splitting of the parent cell during fission can take place in any plane. 

• multiple Fission

Multiple season is also an a sexual method of reproduction in organisms. In multiple season the parent organism split or divide to form many new organisms at the same time. This happens as sometimes during unfavorable condition a cyst or protective wall is formed around the cell of a single cell organism like plasmodium. Inside the protective wall the nucleus of cell is splits or divide several times to form many smaller nuclei called daughter nuclei full stop little bits of cytoplas collect around each daughter nuclei and thin membrane are formed around them full stop in this way many new daughter sales are formed from a single parent cell within the protective wall. In fact as many daughter sales are formed as a number of daughter nuclear produced by the division of the parent nucleus full stop when the favourable conditions arrives the protective layer breaks open and the many daughter sales present in our released each forming a new organism to reproduce many daughter sales at the same time.

2. Budding:- budding is an asexual method of reproduction. In budding, a small part of the body of the parent organism grow out as a bird which then detach and becomes a new organism full stop the asexual reproduction by budding is observed in hydra and Yeast. 

3. Spore formation:- in spore formation, the plant produces 100 of microscopic reproductive units called spore, when the sports case of the plant breast than the sports spread into air. When this airborne sports landed on food undergo favourable condition like damp and warm conditions they germinate and produce new plants. Most of the fungi like rhizopus bacteria and non flowering plant such as f phones and Moses reproduced by the method of formation full stop the common bread mold is a fungus plant whose the scientific name is rhizopus fungus reproduced by the method of a spore formation.

4. Regeneration:- the process of getting back a full organism from its body parts is called regeneration. The simple animals like hydra and planaria show regeneration. This means that in this organisms whole new organisms can be reproduced from their cut body parts. Planaria is a flat warm which is found in freshwater phones and slow moving streams. Planaria poses great power of regeneration. If the body of plane are some how gets cut into a number of pieces then each body pieces can regenerate into a complete plane area by growing all the missing parts.

5. Fragmentation:- the breaking up of the body of a simple multicellular organism into two or more pieces on maturing, each of which subsequently grows to form a complete new organism is called fragmentation. The breaking up of the body of an organism in fragmentation to form New organisms occurs naturally when the parent organism matures. The organisms like spirogyra and sea anemones can reproduce by the method of fragmentation.

6. Vegetative propagation:-

Vegetative propagation is a nice sexual method of reproduction. 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. The green grass grows in the fields after rains from the dry old stems of grass plants present in the fields by the method of vegetative propagation. Bryophyllum plants can be reproduce by vegetative propagation by using either a piece of its stem or its leaves.

Sexual reproduction

Sexual reproduction takes place by the combination of a special reproductive cells called sex cells. Sex cells are of two types: male sex sale and female sex cell. The sex cells are commonly known as gametes. In sexual reproduction a male gamete fuse with a female gamet to form a new cell called zygote. This Jai got then grows and develops into a new organism in due course of time.

Sexual reproduction in flowering plants

The plants in which the sex organs are carried within the flowers and the seeds are enclosed in a fruit are called angiosperms. Angiosperms are come only known as flowering plants full stop the flowering plants reproduce by sexual reproduction method. The sex organs of a plant are in its flowers. The function of a flower is to make male and female gametes and to ensure that fertilization will take place to make new seeds for the production of plant. Sexual reproduction is the most common method of reproduction in flowering plants.

The sexual reproduction in plants takes place in the following steps:

1. The male organ of flower called steman makes the male gametes of the plant. This male gametes are present in pollen grains.

2. The female organ of a flower called carpel makes the female gametes of the plant full stop this female gametes are present in ovules full stop the female gametes present in ovules are also called over or egg cells.

3. The male gametes present in pollen grains fertilize the female gametes present in ovules.

4. Fertilized egg cells grow within ovule and become seeds.

5. The seeds produce new plants on germination.

The main parts of a flower are: Receptacle, sepals, petals, stamen and carpel.

Pollination

For the male game to be able to combine with the female gamete it is necessary that first the Poland grains from the anther of stem and should be carried to the stigma of carpel. The transfer of pollen grains from the anther of a stem and to the stigma of a carpel is called pollination. When the Poland grains from the anther of a flower are transferred to the stigma of the same flower it is called self pollination.

When the following grains from the anther of a flower on one plant are transferred to the stigma of a flower on another similar plant is called cross pollination.

Fertilization

After a pollen grains falls on the stigma, the next step is fertilization. fertilization occurs when the male gamete present in pollen grain joins with the female gamete present in ovule. Amal gamet moves down the Poland tube the pollen tube enters the oval in the ovary full stop the tip of pollen tube breast open and male gamete come out of pollen tube. In ovary the male gamete of Poland combines with the nucleus of female gamet or a present in oviled form of fertilized egg and we say that fertilization has taken place.

Formation of fruits and seeds

The fertilized egg divides several times to form an embry within the ovule. The ovule develops tough quote around it and is gradually converted into a seed. In fact all the eggs in the ovals present in the ovary of a flower get fertilized by male gametes from Poland grains and grow to become seeds. The ovary of flower develops and becomes a fruit. The other parts of flower like sepal petals stamens stigmana style dry up and fall of. Only the ovary is left behind.

Germination of seeds

The seats of 10 from a plant are usually very dry. In this dry estate the seeds can remain alive but inactive for long periods. They are said to be dormant. When a seat gets water air and warmth etc, it begins to grow full stop when a seed begins to grow it is said to germinate. Does the beginning of the growth of seed is called germination of seeds. Germination begins when the Saint absorb water swells and breast through the seed code. The water helps the enzyme to function in the seed. The enzymes digest the store food in cotyledons and make it soluble full stop this soluble food make the radical and plumule present in the seed to grow. The radicle of the seed gross first form the route. The route process down into the soil and begins to observe water and minerals from the soil. After this plumule grows upward to form the suit. The shoot and root grow further when the shoot comes of above the ground a develop green leaves. The green leaves of the suit begin to synthesize on food in the presence of sunlight. This seedling grows gradually and ultimately becomes a new plant.

Sexual reproduction in animals

Fertilization

Sexual reproduction to occur a male gamete must combine with a female gamete. The fusion of a male gamete with a female gamet to form as I got during the sexual reproduction is called fertilization since the male gamete of an animal is called sperm and the female gamete of an animal is called ovum there for we can now say that the fusion of a sperm with an ovum or egg form a zygote during sexual reproduction is called fertilization.

How sexual reproduction in animals takes place:

1. The male parent produces male gametes called sperms. The sperm is a small cell with along tale for movement.

2. The female parent produces female gametes called ova or the ovum is a much bigger cell than the sperm having a lot of cytoplas.

3. The sperm enters into the ovum and fuses with it to form a new cell called zygote. This process is called fertilization. So that zygote is a fertilized ovum.

4. That's I got them divides again and again to form a large number of cells. And ultimately zygote grows and develops to become a new baby.

The male reproductive system

The human male reproductive system consists of the following organs: Testes, Scrotum, Epididymis, Vas deference, Seminal vesicle, Prostrate Glands, and penis. Testes are the oval shaped organ which lie outside the abdominal cavity of a man. Tastes are the primary reproductive organ in males. The function of testis is to make the male sex cell called as form and also to make the male sex hormone testosterone. The testis are outside the abdominal cavity of the body because the sperm formation requires a lower temperature than the normal body temperature. Being outside the abdominal cavity the temperature of scrotum is about 3 degree Celsius lower than the temperature inside the body. The sperms found in testis comes out and go into a colloid tube called Epididymis. 10 pumps get store temporary in Epididymis. From there the sperms are carried by a long tube called vas deference which joins with another tube called urethra coming from the bladder full stop along the path of vas deference the glands called seminal vesicles and prostrate glands and their secretion to sperms so that the sperms are now in a liquid form full stop this liquid plus the sperms it contains is called semen. The secretion of seminal vesicles and prostrate gland provide nutrition to the sperms and also make their further transport easier full stop forms of common passage for sperms and urine full stop and organ called penis which opens outside the body full stop the penis from the men's body into vagina in the women's body during meeting for the purpose of reproduction.

The female reproductive system

The human female reproductive system consists of ovaries, oviducct or fallopian tubes, uterus and vagina. Over is are the oval shaped organs which are inside the abdominal cavity of a woman near the kidneys. A woman has two ovaries full stop primary reproductive organs in a woman. The function of ovaries is to make mature females sex cells and also to make the female sex hormones called oestrogen and progesterone. Each ovary is composed of several thousand follicles which are a kind of unripe eggs or unripe ova. At poverty this follicles mature to form the ripe eggs. Just above the over is are the tubes called oviducts. The fallopian tubes are not directly connected to overris but have funnel shaped opening switch almost cover the ovaries. The ovum released by an overy goes into the oviduct through its funnel shaped opening. The fertilization of egg by a sparm takes place in the fallopian tube. The two oviducts connect to a bag like organ called uterus at their other ends. The growth and development of a fertilized ovum into a baby takes place in the uterus. The uterus is connected through a narrow opening called Cervix to another tube called vagina. Which opens to the outside of the body. Vagina receive the penis for putting sperms into the women's body. Vagina is a tubular abstraction. Vagina is also called worth canal because it is through this passage that the baby is born after the completion of development inside the uterus of the mother.

Fertilization

In human beings internal fertilization takes place. The sperms made in the testis of men are introduced into the vagina of the women through penis during mating full stop in this way millions of sperms are released into the vagina at one time full stop the sperms are highly active and Mobile. The sperms move up through Cervix into the uterus. From uterus the sperms pass into the oviduct. One of the oviducts contains an ovum released by the ovary during ovulation. Fertilization of the ovum takes in the oviduct.

Development of embryo

When the ovum is fertilized in the oviduct than as I got is formed. This I got divides rapidly by mitosis as it moves down slowly in the oviduct and form of hollow ball of hundred of cells. This hollow ball of cells now called an embryo, sinks into the soft and thick lining of the uterus and gets embedded in it. The embroiding of embryo in the thick lining of the uterus is called implantation. After implantation a disk like a special tissue develops between the uterus wall and the embryo which is called placenta. The foetus is connected to placenta in mother's body through umbilical cord. It is true the placenta that all the requirements of the developing foetus like nutrition respiration and excretion etc are met from the mother's body. The time period from the fertilization up to the birth of the baby is called gestation.

Menstruation

We will now describe the sexual cycle in human female. When a girl child is born her over is already contains many thousands of immature over. Which are contained in immature follicles. When a girl richest the age of puberty, then one follicle develops at a time to form a mature ovum full stop on maturing the follicle breasts and the ovum shoots out of the ovary. This is called ovulation. Thus, the release of an ovum from an ovary is called ovulation.

In a normal healthy girl ovulation takes place on the 14th day of the beginning of menstrual cycle of 28 days. This means that ovulation take place in the middle of the menstrual cycle full stop in human females the ovaries starts releasing over egg once every 28 days from the age of puberty. That is in girls ovulation starts when they attend puberty full stop before every evolution the inner lining of the uterus becomes thick and soft with lot of blood capillaries in it. This changes in the uterus and necessary because in case the ovum released by the overy gets fertilized by the sperm and the uterus has to keep this fertilized ovum for further development and supply it with food and oxygen. So that it may grow into a baby in Deu course of time. If however a sperm is not available at the time of a lesson then fertilization of ovum does not take place. Since the ovum is not fertilized so the thick and soft uterus lining having lot of blood capillaries in it is not required. Does the unfertilized over dies within a day and the uterus lining also breaks down. Since the thick and soft uterus lining contents a lot of blood vessels so the breaking of the uterus lining produces blood along with other tissues. This blood and other tissues come out of the vagina in the form of bleeding. We can now say that the breakdown and removal of the inner thick and soft lining of the uterus along with its blood vessels in the form of vaginal bleeding is called menstruation.

Birth control

The population of our country is increasing rapidly day by day full stop true or country has sufficient food resources but still many people do not get sufficient food for their large families, Due to poverty. So every year it is becoming very difficult for our government to provide sufficient food, adequate clothing, good housing and proper education to every citizen of the country. It is there for very important for the couples who are in the reproductive stage of their life to control the size of their families by having fever children by practicing family planning through birth control measures. Family planning enables of couple to decide on the number of children it wants to have and went to have them full stop if a couple has less number of children it can provide good food good clothes and good education to each child. this will make the parents as well as the children happy. So a small family is a Happy family full stop it should be noted that having fever children also keep some other in good health. We should remember that to keep the size of our family small by having less number of children is in our own interest as well as in the interest of our nation. Family planning can be done by practicing birth control measures. Birth control can be done by preventing pregnancy in female and pregnancy can be prevented by adopting a method or procedure by which produce during mating between man and his wife can be prevented from meeting the ovum and fertilizing it. It is possible to prevent fertilization because the ovum is available for fertilization only for a short period. Since frequent pregnancy have a very bad effect on the mothers health and also add to our already exploding population, so a number of techniques or methods have been developed to prevent pregnancy in women.

Birth control methods

The prevention of pregnancy in women is called contraception full stop and any device or chemical which prevents pregnancy in women is called a contraceptive. All the birth control methods can be broadly divided into three categories:

1. Barrier methods

2. Chemical methods

3. Surgical methods

Barrier methods

In the barrier methods of preventing pregnancy the physical devices such as condom and diaphragm are used. Condoms are used by mails by putting them as a covering on the penis. Condom is called 'nirodh' in Hindi. diaphragm is used by females by putting it in the vagina to cover the cervix. Condom as well as diaphragm prevent the sperms from meeting the ovum by acting as a barrier between them full stop and important benefit in the use of condom is that it protect a person from the sexually transmitted disease such as gonorrhea, Syphilis and AIDS. 

Chemical methods

In the chemical methods of preventing pregnancy the females use two types of pills: Oral Pills and vaginal pills, which are made of a specific drugs. The oral pills contains hormones which stop the ovaries from releasing ovum into the oviduct full stop oral pills are also called oral contraceptives. This is a very effective method of preventing pregnancy so long as the pills are taken at the right time. Some women however do experience unpleasant side effects on taking oral pills because they change the hormonal balance in the body. So it is important that the women on pills have regular checkups with their doctor. The vaginal pills contains the chemicals called spermicides which kill the sperms.

Intra-Uterine contraceptive device(IUCD)

The use of intrauterine contraceptive device called copper--T Is also very effective in preventing pregnancy. copper--T is blessed inside the uterus by a doctor or a trend nurse. The iucd prevents the implantation of fertilized egg in the uterus. If a woman uses of copper t as a method of contraception for avoiding unwanted pregnancy then copper take cannot protect her from acquiring sexually transmitted disease.

Surgical methods

Surgical methods of birth control are available for males as well as females. In males a small person of the sperm duct or was difference is removed by surgical operation and both the cut and are ligated properly. This prevent the sperms from coming out. The surgical procedure carried out in the mails is called vasectomy. In females a small portion of the oviducts is removed by surgical operation and the cut ends are tide. This prevents the ovum from entering into the oviducts. Surgical procedure carried out in the female's is called Tubectomy.