Reproduction in Animals Class 8 basic concepts

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1. At the end of this chapter the pupil will be able to: Differentiate between sexual reproduction and asexual reproduction Identify the parts of male reproductive system and female reproductive system Distinguish between internal fertilisation and external fertilisation. Cite examples of viviparous animals and oviparous animals. Develop skill in drawing diagrams like reproductive system, life cycle of frog, binary fission in amoeba etc. Observe and identify various stages in the development of frog Develop interest and enthusiasm in learning biology. Apply the gained knowledge in daily life and derive conclusion from experiences. Learning outcomes and Goals

2. Topics to be covered Sexual Reproduction Male reproductive system Female reproductive system Fertilisation Embryonic development in human beings Viviparous and Oviparous animals Metamorphosis Asexual reproduction-Budding and Binary fission

3. Reproduction is a process by which an organism produces offsprings that are biologically or genetically similar to the parent organism Reproduction in animals is of two types – Asexual Reproduction Sexual Reproduction Reproduction in animals

4. Sexual reproduction  is the process in which new organisms are created by combining the genetic information from two individuals of different sexes. In higher animals a specialised Reproductive System helps in carrying out sexual reproduction Sexual Reproduction

5. Male Reproductive System It consists of a pair of testes, sperm ducts and penis. The testes produce numerous male gametes called sperm. Sperms are carried through sperm ducts to the urethra which passes through muscular penis.

6. Sperm is a microscopic, motile, male reproductive cell or gamete composed of a head, middle piece and tail. The tail helps sperms in swimming. The sperm helps in transferring the genetic material to the female body during the mating. Sperm

7. Fem ale Reproductive System It consists of a pair of ovaries, oviducts (fallopian tubes) and uterus. The ovary produces the female gamete called ovum or egg. The oviduct collects the ovum and passes it to the hollow muscular structure called uterus. The lower side of the uterus is called cervix. A narrow muscular passage called vagina connects the outside with uterus

8. Ovum or egg cell  is a microscopic, female reproductive cell or gamete. Each ovum is a rounded and non-motile structure. Egg is much larger than the sperm. Ovum

9. Fertilisation Fertilisation is the process of fusion of the sperm and the ovum (egg). The nucleus of the sperm fuses with the nucleus of the ovum to form a zygote or fertilised egg

10. The type of fertilisation in which the fusion of sperm and ovum takes place inside the female body is known as internal fertilisation. Eg. Human beings, cat , lion, snake , birds ,deer etc. Internal Fertilisation

11. The process of releasing the eggs and sperms into the water by frogs and fishes is termed spawning Hundreds of eggs are produced by the female frog at a time. The eggs are delicate and are protected by a jelly like envelope Spawning

12. The type of fertilisation in which the fusion of sperm and ovum/egg occurs outside the female body is called external fertilisation. Eg. Fish, frog, starfish, sea anemone, sea urchin, coral etc. External Fertilisation

13. In-vitro fertilisation  (IVF) is a process of fertilisation   where an egg  is combined with sperm outside the body  (in glass test tube). After the fertilisation the embryo is deposited in same or another woman's uterus for successful pregnancy. In- Vitro Fertilisation

14. Embryonic development in Human Zygote Embryo Foetus

15. Embryonic development in Hen

16. The animals which undergo internal fertilisation and later give birth to young ones are called viviparous animals . Eg. Human beings, elephant, dog, giraffe, zebra, tiger etc.

17. The animals which undergo internal fertilisation and later lay eggs which hatch into young ones are called oviparous animals . Eg. Snakes, insects, birds, lizards tortoise, turtle etc.

18. Metamorphosis Frogs have multiple stages in their life cycle such as egg, tadpole, tadpole with legs, froglet and frog. The drastic changes taking place during the development of egg into an adult is termed metamorphosis

19. Asexual Reproduction Asexual reproduction  is a type of reproduction which does not involve the fusion of gametes.The offspring that arise by asexual reproduction from a single cell or from a multicellular organism inherit the genes of that parent.

20. Budding in Hydra Hydra develops a bud on its tubular body. The bud grows in size and gets detached from the parent hydra. The newly formed hydra is called daughter hydra. This type of asexual reproduction in hydra is termed budding.

21. Binary Fission in Amoeba The nucleus of the amoeba divides into two followed by the division of the cell. Each daughter amoeba receives one nucleus. The process of producing new amoebae by splitting the parent amoeba into two is termed binary fission.

22. Cloning is a process of generating a genetically identical copy of a cell or any other body part or a complete organism. Cloning

23. Cloning of Dolly

24. 1. What is the function of sperm? 2. Where does fertilisation take place in fish ? 3. Why do female frogs produce hundreds of eggs at a time? 4. What is the difference between frog’s egg and hen’s egg? 5. Mention some examples of oviparous animals. 6. What is common between budding and binary fission? Recapitulation

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