REPRODUCTION.pptx
- 1. REPRODUCTION
- 2. Asexual Reproduction • It is a mode of reproduction involving a single parent. Asexual reproduction does not involve the fusion of gametes, and therefore, the off-springs produced are genetically identical to the parent. • The organisms produced by asexual reproduction are less diverse in nature. • This type of reproduction is practised widely by unicellular organisms.
- 3. Modes of Asexual reproduction 1. Fission • Fission is defined as the splitting of the organisms into two halves and each half gives rise to a new organism. For example, Amoeba, bacteria. • The most common type of fission is binary fission. It is a division of organisms such as bacteria into two or more parts. a) Binary Fission -> The most common type of fission is binary fission. It is a division of organisms such as bacteria into two.
- 4. b) Multiple Fission Plasmodium reproduces through multiple fission where one single cell divides its nucleus to form many nuclei. This is followed by the division of the cell body to form daughter cells, each having a single nuclei.
- 5. 2. Fragmentation • Fragmentation is another mode of asexual reproduction in which organism breaks into pieces and each piece give rise to a new organism. For example, Spirogyra
- 6. 3. Regeneration • Regeneration is the ability to form new organisms from body parts. Cut or broken part generates a new organism. For example, Hydra, Planarians. • Regenerative cells help to regenerate.
- 7. 4. Budding • Budding is a type of asexual reproduction in which a small cyst-like structure is formed on the parent’s body, which gives rise to a new individual. • Bud may remain attached to the parent (yeast) or may separate and become a new individual (hydra).
- 8. 5. Spore formation • Organisms such as fungi (Rhizopus) make spores that can grow into completely new individuals when dispersed from their fruiting bodies. • Spores are produced inside sporangia. • They are covered by a thick outer layer that protects them in adverse conditions. • When spores get suitable environmental conditions, they germinate and begin to grow.
- 9. 6. Vegetative propagation • This is a type of asexual reproduction seen in plants. • The vegetative parts of the plant, like leaves, stems, and roots, give rise to a new plant. • Vegetative propagation can be artificial or natural. • Natural vegetative propagation happens through Tuber (e.g. Potato) leaves (e.g. bryophyllum), stem (e.g. turmeric, ginger), bulbs ( e.g. onion, lily), etc. • Artificial methods include cutting (rose), grafting, layering and plant tissue culture.
- 11. • Reproduction enables and ensures the continuity of species, generation after generation. • Reproduction at its most basic level involves making copies of the blueprints of body design. • The chromosomes in the nucleus of a cell contain information for the inheritance of features from parents to the next generation in the form of DNA (Deoxyribo Nucleic Acid) 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 designs. • The cells use chemical reactions to build copies of their DNA. This creates two copies of the DNA in a reproducing cell, and they will need to be separated from each other. • To ensure that, a cell divides itself into two cells, each cell containing its own DNA and cellular apparatus. • Now, both these cells will be identical, but we cannot say that copying of the DNA will be 100% identical. • There might be some variations in the chemical reaction which means organisms cannot create exact copies of themselves. VARIATION
- 12. SEXUAL REPRODUCTION Sexual reproduction involved two different parent organisms involving a female and a male parent. • Significance of Sexual Reproduction • Sexual reproduction is the source of variation. The mixing of two organisms gives rise to new recombinants or variants. Sexual reproduction involves the mating of germ cells also known as gametes. When male gametes and female gametes each with a haploid (half) set of chromosomes combine they will form a diploid zygote. Zygotes undergo repeated divisions to form a new organism. • In humans, the male gamete is small and motile whereas the female gamete is large and non- motile.
- 13. Sexual reproduction in flowering plants :- a) Reproductive parts of a flower :- • The stamen and pistil are the reproductive parts of the flower. • Stamen is the male reproductive part. It produces pollen grains in the anther which contains the male germ cell (male gamete). • Pistil is the female reproductive part. It produces ovules in the ovary which contain the female germ cell (female gamete).
- 14. b) Pollination :- The transfer of pollen grains from the anther to the stigma of a flower is called pollination. It takes place by wind(Anemophily), water (Hydrophily) insects (Zoophily), Birds (Ornithophily) or Bat (Entomophily, Animals (Chiropterophily). It is of two types:- (A) Self pollination: If the pollen grains are transferred from the anther to the stigma of the same flower it is called self pollination. E.g.- Pea, Wheat, Rice, Chinarose etc. (B) CROSS POLLINATION:- it is the transfer of pollen grains from the anther of one flower to the stigma of another flower born on other plant of the same species.
- 15. c) Fertilisation :- • After the pollen grain is transferred to the stigma it produces a pollen tube which passes through the style and enters the ovary and ovule. • In the ovule the male germ cell (male gamete) fuses with the female germ cell (female gamete) to form a zygote. This process is called fertilisation. After fertilisation the zygote divides several times and forms the embryo which then develops into the seed and the ovary develops into the fruit.
- 16. Germination: It is the initial stage in the growth of a seed to develop into a seedling under appropriate conditions.
- 17. SEXUAL REPRODUCTION • It is the process of producing new organisms from two parents by making use of their sex cells or gametes. e.g- human, fish, dogs, cats and most of the flowering plants. •Thus the two major process i.e. formation of gametes and fusion of gametes constitutes sexual reproduction. •Two sexes namely Male( producing male gamete / Sperm) and Female (producing female gamete / Ova) are involved. Significance of sexual reproduction: 1. It promotes variation and thus promotes diversity of characters in the offspring’s. 2. 2. It plays a prominent role in the origin of new species.
- 18. SEXUAL REPRODUCTION IN HUMAN BEINGS • Sexual reproduction involving male reproductive organ and female reproductive organ (growth to •The reproductive organs of human being i.e. Testis in male and ovary in female become functional only after attaining sexual maturity. In male sexual maturity is attained at the age of 13-14 years while in female at the age of 10-12 years. This is known as the age of puberty. PUBERTY: It is the age at which the sex hormone or gametes begin to be produced and the boy and girls becomes sexually mature.
- 19. SEXUAL MATURITY IN HUMAN BEING • Various changes takes place in human body at the time of sexual maturity:- • Changes common in both boys and girls:- 1) Thick hair growth in armpits & genital area between the thigh (also called Pubic region). 2) 2) Thinner hair on legs, arms and faces. 3) 3) Oily skin and appearance of pimples
- 20. Human Reproductive System • a) Male reproductive system : • It consists of two portions one that produces germ cell and the other that deliver the germ cell to the site of fertilisation. • The human male reproductive systems consists of the following organs:-
- 21. • The male reproductive system comprises a pair of the testis, glands, accessory ducts, and male genitalia. • The testis is the site where male gametes or germ cells are produced. They are located outside the abdominal cavity in a sac-like structure known as the scrotum. This is to maintain the lower temperature required for the formation of sperm. Testis produces the male hormone testosterone needed for the development of secondary sexual characteristics in males such as the formation of beard and moustaches and also in the development of sperm. • Vas deferens is a duct that transports sperm to the urethra, which is a common passage for urine and sperm ejaculation. • Prostate glands and seminal vesicles are also found in males to nourish and for easy transport sperm in the female genital tract. All these secretions along with sperm form the semen.
- 22. Female Reproductive System • The female reproductive system consists of a pair of ovaries, uterus, cervix, vagina, and external genitalia.
- 23. • Female eggs or ova are produced in the ovaries. The formation of ova in the ovaries is known as oogenesis. • The ovary produces female hormones such as oestrogen, progesterone. These hormones are needed for female sexual development and well as for pregnancy. • The fallopian tube carries ova from the ovary to the womb. Two oviducts joined to form the uterus. Uterus then opens into Vagina via the cervix.
- 24. • Sperm enter into the female vagina at the time of sexual intercourse. Then the sperm reaches the fallopian tube where it fuses the ova to form a zygote. This is known as fertilisation. • Then the zygote divides to form an embryo. The embryo gets implanted into the uterus. The embryo development occurs in the uterus to form the foetus. • Mother supplies nutrition to the growing foetus via the placenta. • The placenta helps in the exchange of nutrients, gases and the removal of excretory products. • The development of a child inside the womb of the mother takes place for about 9 months. Then the rhythmic uterine contraction leads to the delivery of the baby outside the female body.
- 25. Menstruation • If the egg is not fertilised, the uterine lining is shed off in the form of fluid known as menstrual fluid. The discharge occurs from the vagina as blood and mucus. This is known as menstruation. • It lasts for about 2 to 8 days.
- 26. REPRODUCTIVE HEALTH • It is defined as the state of well being in terms of safe sex, reproductive fitness as well as the absence of any reproductive diseases. Unsafe sex leads to different diseases which are known as sexually transmitted diseases. Some of the sexually transmitted diseases are as follows- • Gonorrhoea is caused by bacteria • Syphilis is caused by bacteria • AIDS (acquired immunodeficiency syndrome) is caused by a virus HIV(human immunodeficiency virus)
- 27. VARIOUS METHODS OF CONTRACEPTION • CONTRACEPTIVE -: • Contraceptives are devices that prevent unwanted pregnancy and help avoid STDs. • Contraceptives can be of various types such as mechanical barriers, hormonal/chemical methods, surgical methods, etc. • 1. Mechanical barriers • Condoms are one of the most effective methods of contraception. • A mechanical barrier that stops the semen from entering the female tract preventing pregnancy. • It also avoids the possibility of contracting STDs. • Note -: Diaphragms are barriers that can be added inside the female reproductive tracts.
- 28. 2. Chemical method a) Contraceptive pills change the level of hormones in the body that prevents the release of the ovum from the ovaries. b) Emergency pills are those pills which can be taken after coitus to avoid pregnancy. They quickly change the level of hormones in the body and prevent a successful implantation even if the egg gets fertilized. 3. IUD (Intrauterine Device) • They can be used for a couple of years. • It is a device that is inserted into the uterus, changing its shape and preventing successful implantation of the zygote. E.g. loop or Copper T. 4. Surgical method (Sterilization) • Sterilization is a surgical method of going permanently sterile. • This can be done in both males and females. • In males, it is called vasectomy and in females, it is called