Reproduction is a process by which every living organism makes a copy like itself as seen in parents to their children. This is only done because of replication of DNA (deoxyribonucleic acid) by transferring the genetic information from the parents to their offsprings or simply we can say that passing their physical or mental character genetically to main the chromosome number of species.
Variations are beneficial to the species than individual because during certain environmental conditions their is so drastic change that their survival of species becomes difficult. For example, if their is sudden rise in temperature of water, then most of the bacteria living in that water would die. So only few variants that can resistant to heat would be able to survive. However, if these few variants were not there, then the entire species of bacteria would have destroyed. Thus, these variants help in the survival of the species.So all variations are not necessarily beneficial for the individual organisms.
Asexual reproduction occurs in different ways in different organisms. So, binary fission and multiple fission both are the types of asexual reproduction.
Binary fission:- It is the division of parent cell into two small daughter nucelii. Mainly three types of binary fission shown in some organisms- Irregular, longitudinal, transverse. Like in protozoan protists, the replicated chromosome separated by intranuclear mitosis and starts dividing. Then, the cytoplasm constricts between two separating nuclei and forms two equal sized daughter nuclei with a nucleus (eg. Amoeba shows irregular fission, Euglena shows longitudinal fission and Paramecium shows transverse binary fission). Or like in Planarians also, they are divided by transverse binary fission with the equal sized daughter individuals.
Multiple fission:- Unlike binary fission, the division of parent cell will be into many small daughter nuclei. And it can be shown in mainly two organisms- Plasmodium or Amoeba. Plasmodium is a malarial parasite, when multiple fission takes place in adults or in its encysted zygote (called sporogony) and their daughter individuals are then called merozoites.
Spores are produced from sporangium, they do not require any medium for the dispersal and are light in weight, so can easily be transferred for germination. Spores can be remain alive but not actively growing till their favourable condition comes, they help organisms to survive or to get over the stress phase. Many spores can transferred at once, so reproduction is very quick, that’s why organisms are benifitted if they reproduces through spores. Major advantage is that spores are large in number, so population will also increases and survival chances are also high.
Regeneration is the process of renewal, restoration and growth of tissues to the organisms itself that makes organisms or ecosystem resillience to the natural fluctuation that is done by the disturbance. And in complex organisms, different tissues and organs have their different structures. So, the rengeneration process is unable to give rise to new individuals from complex organisms.
Vegetative propagation occurs without seeds. The lower plants reproduce vegetatively through budding, fission, fragmentation, buds, spores etc. Every part of the plant such as roots, stems, leaves and buds takes part in vegetative propagation and can give rise to same new plants. Plants which have superior traits are vegetatively propagated cause they can give rise to identical plants. Vegetative propagation is of two types:-
Natural vegetative propagation
Artificial vegetative propagation
Vegetative propagation is the only method of reproduction in those plants who lost their capacity to produce seeds, eg. Banana, oranges, rose etc. Vegetative propagation can be done by plant tissue culture for the production of disease free plants.
DNA is a genetic material which carries information from the parents to their offspring by the process DNA replication in which complementary strand is made from the template strand of DNA with the help of various enzymes. If any error or mutation occurs in copying DNA, then there may be possibility of abnormality occurance in the offsprings from their parents. That’s why copying of DNA without an error is an essential process of reproduction.
Pollination:- Transfer of pollen grain from the anther (male part of the flower) of stamen to the stigma (female part of the flower) of carpel is known as pollination. It is of two types:-
Self pollination:- It involves the transfer of pollen grains from the anther to the stigma of the same flower or genetically similar flower.
Cross pollination:- It involves the transfer of pollen grains from the flower of one plant to the stigma of the flower of another plant.
Transfer of pollen grains can be occur through many agents like anemophily (wind pollination), hydrophily (water pollination), entomophily (insect pollination), ornithophily (pollination by birds) and chiropterophily (bat pollination).
Fertilisation:- Fusion of haploid male gamete (spermatozoan) and a haploid female gamete (ovum) and they together forms a diploid cell, i.e, zygote is known as fertilisation.
Seminal vesicles and prostate gland both are the accessory sex glands in male reproduction system.seminal vesicle secrete fluid that consist of nutrientsthat support sperm until fertilisation occurs.
Seminal vesicles contains hormone called prostaglandins, which stimulate contraction in the female reproductive system for the transportation of sperms to the oviduct with ovum.
Prostate gland secretes thin, milky and acidic fluid which is discharged into the part of urethra. It also contains sperms nutrient and some anticoagulant enzymes. Their secretion activates the sperms to swim fluently.
At the time of puberty, many changes can be seen in girls. Hormonal changes can be seen, girl’s body increase in size like hips become rounded in shape and they get more curvy waist, voice become thin. Vagina, breast size and nipples size get increases or we can say they begin to develop. And at the time of puberty menstruation occurs.
Embryo gets nourishment inside the mother’s body through the placenta. Placenta is an organ which forms in uterus during the pregnancy and is less than 1kg in weight. It helps to bring the foetus and the maternal blood close enough for the exchange of oxygen and nutrition and it also removes the waste product from the baby’s blood. And, it also has the umbilical cord (naval string) which is attached near the centre of placenta to the foetus.
Copper- T cannot help in protecting a woman from sexually transmitted diseases. An Intrauterine device is present which contains copper in female’s body. It is used for the birth control and as a contraceptive method.
Yeast
Yeast is a unicellular fungi and reproduces asexually by the formation of spores. During the process of budding, the parent cell produces a small bud which grows in size. Then, the parent cell nucleus divides and the daughter nuclei goes in the bud. And then the bud gets detached and grow separately like a new individual on the substratum.
Organisms survive only to reproduce. Reproduction is very important for the stability to populations of species by extending their genernation or the population of same species from the existing generation. It also helps in the study of evolution by recording the data of their ancestors to the new generation of same species.
There can be many reasons for adopting contraceptive methods:-
The main reason for adopting the contraceptive methods is birth control or the population control.
Condoms are the safeguard against the infection of AIDS (acquired immune deficiency syndrome) or STD (sexually transmitted diseases)
The induced abortion method of contraception is used to get rid of unwanted pregnancy by the unprotected intercourse, when women get raped by someone, or where mother’s life or foetus is in danger and when women is not able to conceive the baby due to the weak immune system of the baby.
Vas deferens
Vas deferens is a tiny muscular tube found in male reproductive system, which carries sperms from epididymis to the ejaculatory ducts.
(d) Pollen grains
Anther is the male part of the flower. It consists of pollen grains and they carried to the stigma (female part of the flower) through various agents like butterflies, wind, water for the process of reproduction.
Reproduction is a process to produce a young one similar to their parents genetically or morphologically. There are two modes of reproduction:- asexual or sexual reproduction.
Sexual reproduction is the process of forming a diploid cell zygote from one haploid male gamete or one haploid female gamete. In this two parents are involved, and when a offspring is formed than variation occurs and variation is the key factor of the evolution. If there is no variation, population cannot respond to the changing environment and may face an risk of being extinct from the environment.
Asexual reproduction is the process of making two or more daughter cells from one parent cell, i.e, only one parent is involved. So, there is no variation occurs as in sexual reproduction occurs. It is dynamic, static where no evolution occurs in their morphological characters, where each offspring is genetically or morphologically identical to each other.
The long term survival period happens in sexual reproduction than asexual because of the variation. When genetic variation occurs, it helps the organism to survive in the drastic environmental changes.
Testis are the primary sex organs in male reproductive system. It helps in maintaining the health of male body. sperm produces in seminiferous tubules, and also produces a hormone like androgen called testosterone and secrets inhibin protein. Testosterone is the male sex hormone helps in developing the male reproductive tissues like testis or prostate or in the growth of body muscles and hair.
Menstruation occurs at the time of puberty in females. Menstruation occurs to prevent the pregnancy phase. It releases the tissues which supports the foetus to grow during the pregnancy. Menstruation is the bleeding phase, where an egg released by female does not get fertilized or attached to the uterine wall then uterine lining dies due to deficiency of hormone (progesterone), and the lining of fallopian tube breaks down and then the blood oozes out from the ruptured vessels through the vaginal opening.
There are various birth control methods which prevent fertilization (meeting of a sperm to ovum to form a zygote) is known as contraception. There are mainly three major types of contraception:-
Temporary methods
Permanent method
Medical termination of pregnancy
Temporary methods:- they contain natural, barrier or physiological methods of the birth control. In natural, Lactation amenorrhea (absence of menstruation) method is used, where there is intense lactation occurs during the absence of periods in females which prevents from the birth control. In barrier methods- condoms, cervical caps, vaults and Intrauterine devices are used for the contraception. Or, in physiological devices oral pills or injections can be taken for the birth control which confirms the ovulation occurance in females by secreting the FSH (follicle stimulating hormone) or LH (Luteinizing hormone).
Permanent method:- it is a surgical method for the birth control. In man it is known as Vasectomy or in females it is known as tubectomy. Vasectomy is the process of removal of short segment of each vas deferens and tying up of the remaining ends tightly with the surgical thread. And tubectomy is the process of removal of fallopian tube and the remaining ends are tied up tightly with the surgical thread.
Medical termination of pregnancy:- also called induced abortion. It is the voluntary termination of a pregnancy before the foetus making. It is done to get rid of unwanted pregnancy, rapes etc.
In unicellular organisms, asexual reproduction occurs where there is only one parent is involved and no gamete production or parthenogenesis occurs, where one parent cell gets divided into two or multiple daughter cells by binary or multiple fission (eg. Binary fission shown in bacteria, amoeba, planarians and multiple fission shown in plasmodium).
In multicellular organisms, sexual reproduction occurs where two parents are involved to form a zygote or parthenogenesis occurs. All mammals human beings, apes etc. show sexual reproduction process where mother shows viviparity, i.e, gives birth directly to the young ones.
Bisexual flower contains both stamen (male part) and pistil (female part). If the stamen is removed artificially it will show no effect on the flower producing capability of the flower because it still contains the female part. And if the flower has only a female part then cross pollination can occur. The stamen of the other plant may get fertilized with the pistil or the carpel of the flower and thereby they produce fruits.
Yes, we can consider the cell division as a type of reproduction in unicellular organisms because unicellular organisms reproduce asexually and form the new individual identical to the parent. Asexual reproduction involves only one parent cell which get divided into two daughter nuclei and forms the new individual.
Clone is the process of producing the individuals with the identical characters or identical DNA. Clones are formed in the asexual reproduction because there is only one parent is involved. As it involves only one parent there will be no genetic variation and they produce the identical individual. Hence, offspring are produced clone by the asexual reproduction.
Offspring and parents of organisms reproduce sexually have the same number of chromosomes because of halving of chromosomes during the gamete formation. The number of chromosomes remains the same as in the somatic cell. The two haploid gametes in the chromosome form diploid numbers of chromosomes. As shown below:-
Yeast show asexual reproduction and forms the new individuals by the budding process. Yeast requires energy for the growth and the cell division. Sugar is the essential element for the multiplication of the yeast because it provides energy but water does not provide energy. Thus yeast multiplies in the sugar solution.
Large number of spores or availability of moisture and nutrients in bread provides the suitable environment for the spores to grow into mould. Hence mould grows profusely on the moist slice of the bread.
Sexual reproduction involves the production of male and female gametes by the same parent. When the two opposite gametes produced by the same individual is known as bisexual and these two gametes together forms a zygote which develops into a new organism by involving the meiosis process leads to variation. Variation does not occur in asexual reproduction.
By involving the meiosis process i.e, halving of the parental chromosomes inside both of the paternal and the maternal gametes and by their fusion zygote formed which results in the restoration of the original parental number of chromosomes which leads to increase in the genetic diversity.
Yes, planarians divided by the transverse binary fission which is a type of asexual reproduction.
Process:- they fix their posterior body part to the substratum and moves their anterior part and then exerts the forceful pull over the posterior part. Due to this the middle part gets stretched and breaks down. Anterior part regenerates the posterior one and then anterior part re- growth occurs and two new individuals are formed.
| Animals | Chromosome Number |
| Humans | 46 |
| Chimpanzee | 48 |
| Cat | 38 |
| Cattle | 60 |
| Rhesus Monkey | 42 |
| Plants | Chromosome Number |
|---|---|
| Mango | 40 |
| Potato | 48 |
| Sugarcane | 80 |
| Tobacco | 48 |
| Wheat | 28 |
a) Size of the organisms does not depend on the number of chromosomes.
b)
c) Chromosomes are thread-like structures located inside the nucleus of the cell of plants and animals. Chromosomes are made up of proteins and single molecules of DNA (deoxyribonucleic acid). Hence the more the number of chromosomes the greater the DNA content.
Male and female gametes posses equal number of chromosomes so if in the tobacco plant, male gamete posses 24 chromosomes then female gamete will also be 24 in number. As both the gametes share their equal number of chromosomes that would be double then the zygote will contain 48 numbers of chromosomes (by combining male and female gametes).
Pollination:- Transfer of pollen grain from the anther (male part of the flower) of stamen to the stigma (female part of the flower) of carpel is known as pollination. It is of two types- Self pollination (transfer of pollen grains from the anther to the stigma of the same flower or genetically similar flower), Cross pollination (transfer of pollen grains from the flower of one plant to the stigma of the flower of another plant). There are various agents which carries the pollination process like anemophily (wind pollination), hydrophily (water pollination), entomophily (insect pollination), ornithophily (pollination by birds) and chiropterophily (bat pollination).
Fertilisation:- Fusion of haploid male gamete (spermatozoan) and a haploid female gamete (ovum) and they together form a diploid cell, i.e, zygote is known as fertilisation.
Pollination and fertilization are interconnected. If there is no pollination then there will be no fusion of male and female gametes and then fertilization doesn't take place.
The number of the chromosomes in parents and offspring remains constant due to halving of chromosomes during the gamete formation and this takes place by the process of meiosis. Gametes contain only half of the amount of DNA from both the parents as compared to the normal cell. And, when the female gamete combines with the male gamete it will form a new zygote after the fertilization process and chromosomes become equal to that of somatic cells. And then the mitosis process takes place for the rest of the stages of the life cycle.
After the fertilization process, the zygote will locate in the ovary of the female.
We came into life to reproduce or we can say that we reproduce to carry forward our generations or lineage. If there will be no reproduction no continuity of lineage occurs then gradually the species will be extinct from the environment and there can be various factors that are responsible for the extinction other than reproduction like competition for food, predation, and parasitism etc. So we can say that reproduction is linked to the stability of the population of a species.
General growth begins with the birth of the individual and growth means growth of body size and shape; whereas the sexual maturation is attained after the specific age and this phase is known as adolescence or the puberty stage. In males maturation is attained between the age of 13- 16 years and in females, sexual maturation is attained about the age of 13. Many hormonal and body changes occurs during this phase.
Path of sperm during ejaculation in male reproductive system is:
Testes → Vasa Efferentia → Epddidymis → Vasa Deferens → Ejaculatory ducts → Urethra
Functions of the glands are as follows:-
1. Testes:- They are primary sex organs. They consist of seminiferous tubules which leads to the spermatogenesis process by producing spermatozoa and sertoli cells which provide nourishment to the developing spermatozoa. Main function of the testes is secretion of testosterone.
2. Prostate gland:- Ensures the production of fluid that carries with the sperm cells from testicles and from other glands, makes up semen. Its muscles also ensure that semen is forcefully pressed into the urethra and expelled out during the process of ejaculation.
3. Cowper’s gland:- It lies below the prostate gland. They secrete alkaline mucus which is discharged into the part of urethra. Mucus coats the urethra before the release of sperms which helps to neutralize acidic urine remaining in the urethra.
4. Seminal vesicles:- Fluid contains sugar fructose, coagulating enzymes, prostaglandin hormone. Fructose provides energy to spermatozoa for swimming. And the prostaglandin hormone stimulates contraction in the female reproductive tract which helps in the meeting of the sperm and ovum in oviduct.
5. Other glands:- Prepuce contains perpetual gland which produce sebaceous substance.
If the fertilization does not occur in uterus following changes can be seen:
Implantation is the attachment of the blastocyst to the uterine wall in females. It takes place about seven days after fertilization. Several changes are observed in the uterus subsequent to implantation of young embryo:
There are several birth control methods and are also known as contraception methods and the mechanical barrier method is one of them.
1. They prevent sperm entry into the vagina of females and prevent unwanted pregnancy.
2. There are mainly three types of mechanical barrier- 1. Condom, 2. Diaphragm, Cervical caps and Vaults, 3. Intrauterine Device (Copper- T).
Diagrams:-
3. They prevent from being affected during the sexual intercourse with the infected person, i.e, from sexually transmitted diseases.
a) Production of egg – Ovary (primary sex organs of females, helps in the production of ova)
b) Site of fertilization – in ampulla of fallopian tube (fertilization is the fusion of male and female gametes to form zygote)
c) Site of Implantation – Uterus (implantation is the attachment of the blastocyst to the uterine wall in females)
d) Entry of the sperms – Vagina
Diagram:
The ratio of the chromosome number between an egg and its zygote is 1:2. The ratio will always be 1:2 because the egg contains 23 numbers of chromosomes and zygote contains 46 chromosomes. Female contains only X sex chromosome but male contains X and Y sex chromosome which decides the sex of the child. So, when the zygote formation occurs the egg will always contain 1 chromosome but sperm contains either X or Y chromosome.
Asexual reproduction is the process of making two or more daughter cells from one parent cell, i.e, only one parent is involved. So, there is no variation as in sexual reproduction occurs and each of the offspring is genetically or morphologically identical to each other. Budding (formation of daughter individual from the bud arise on the parent body and detached after maturation and forms new individual, eg. Hydra, yeast), fragmentation (when the parent cell nucleus divides into multiple fragments and forms new individual from each fragment) and regeneration (formation of individual by restoring or replacing the damaged cells, tissues and organs); all three are the types of asexual reproduction that involves only single parent cell and where no gamete formation occurs. Hence they are considered as asexual type of reproduction.
Planaria show binary fission where their body is divided transversely and cuts down into two pieces. Each cut piece has the ability to regenerate into the new individual. As shown in figure:
| Asexual Reproduction | Sexual Reproduction |
|---|---|
| Asexual reproduction is the process of making two or more daughter cells from one parent cell. | Sexual reproduction is the process of forming a diploid cell zygote from one haploid male gamete or one haploid female gamete. |
| In this only one parent is involved. | In this two parents are involved. |
| No variation occurs. | Variation occurs. |
| Gametes are not formed. | Gametes are formed. |
Sexual reproduction results in the perpetuation and the multiplication of the species. It contributes to the evolution of the species by introducing variations in a population and there are various reasons for this:
1. Genes are contributed by the two parents.
2. DNA replication leads to variation.
3. It leads to an increase in the number of individuals and hence contributes towards evolution.
| Pollination | Fertilization |
|---|---|
| Transfer of pollen grain from the anther (male part of the flower) of stamer to the stigma (female part of the flower) of carpel is known as pollination. | Fusion of male gamete and a female gamete and they together forms a dipliod cell, i.e. zygote is known as fertilisation. |
| Agents that carry the pollination process like wind pollination, water pollination, insect pollination, pollination by birds and bats. | It is achieved by growth of pollen tubes so that male gamete reaches the female germ cells in the plants is known as siphonogamy and in animals it is achieved as the fallopian tubes. |
| Leads to fertilization. | Lead to production of seeds in plants and production of zygote in animals. |
Ovary is the site of fertilization.
Diagram of a pistil showing pollen tube growth and its entry into the ovule:
| GAMETES | ZYGOTE |
|---|---|
| Gametes are formed by meiotic division. | Zygote is formed by mitotic division. |
| Gametes are produced by male and female. | Male and female gametes fuse to form a single cell called zygote, process is known as fertilization. |
| They are haploid i.e, halves number of chromosomes. | They are the fusion of two haploid gametes i.e, diploid- has double number of chromosomes. |
| Gametes are produced for the sexual reproduction. |
Zygote is formed by the fusion of gametes and then forms the embryo. |
Diagram:-
Male gametophyte:- Gamete producing organ is Anther.
The male gametophyte is derived from the Microspore or the pollen grains which is produced inside the pollen chamber of another by forming a pollen tube. The mature male gametophyte is 3- celled, one vegetative tube cell or two male gametes.
Female gametophyte:- Gamete producing organ is Ovary
The female gametophyte is derived from the Megaspore or the pollen grains which are formed inside the nucleus of the ovule and always remain embedded within the membrane of the megaspore. The mature female gametophyte is 7- celled, an egg, two synergids (two small nuclei near the egg), three antipodes and a central cell.
Placenta is a reddish- brown disc and less than 1kg in weight. Foetal surface is smooth and has the umbilical cord
attached to the centre of placenta to the foetus. It contains a large number of branching villi from the vascular chorion on the embryo’s side of the tissues, formed in the uterine wall. These villi contain blood cells and bear microvilli which increase the surface area for the exchange of materials by diffusion, active transport and pinocytosis.
Placenta plays an important role in bringing the foetal and the maternal blood close enough to permit the exchange of materials between the two of them. Glucose, amino acids, proteins, lipids, water, mineral salts, vitamins, hormones, antibodies and oxygen are passed from mother to the embryo. Placenta serves as the nutritive, respiratory and excretory organ of the foetus or the embryo.
The birth control methods which deliberately prevent fertilization are known as contraception. Contraceptive methods should be user- friendly, easily available, effective and with no side effects. There are various contraceptive methods to prevent fertilization or pregnancy and for the birth control are following:-
Permanent Method or surgical method:- This surgery can occur in both male and female, known as Vasectomy in males and Tubectomy in females. Their operation is very minor and performed by giving low dose or local anesthesia. It involves the removal of the short segment of fallopian tubes in females and vas deferens in males and the remaining ends are tied up tightly with the surgical thread. Thus prevents fertilization by re- absorption of sperms into the body.
Diagram:
Once in a month, the mature ovum from one ovary is released. Ovaries are the solid organ which is composed of connective tissue stroma. The egg is conveyed from the ovary to the fallopian tubes. During the copulation, male discharges the semen into the female’s vagina. Then sperm from the vagina reaches the ampulla by their own efforts and partly by the action of uterus and fusion of spermatozoan and the ovum is known as fertilization.
As the menstrual cycle occurs in about 28 or 29 days this means that one egg is released in one month for fertilization. Thus we can say that fertilization can occur only once in a month.
Reproduction is a biological process in which an organism gives rise to the new individual which is similar to itself and this process is very essential for organisms because it enables the continuity of the species lineage after generations. If there will be no reproduction no continuity of lineage occurs then gradually the species will be extinct from the environment.
Reproduction also makes balance between mortality and the natality rate which arises due to the various factors. Hence reproduction helps in the stability of the species.
Disease that spreads from person to person through sexual intercourse with the infected person is known as Sexually transmitted diseases (STD S ) or venereal diseases (VD) or reproductive tract Infection (RTI). This leads to various diseases like HIV leading to AIDS (acquired immunodeficiency syndrome), gonorrhoea, syphilis, genital herpes, hepatitis- B.
Preventions:-
1. One must avoid sexual intercourse with an unknown person or multiple persons.
2. Use condoms or other contraceptive methods during intercourse.
3. If you have any doubt, one must consult a qualified doctor without delay.
4. Avoid sharing of trimmers, razors, towels and underclothing.
