8th Class Science Reproduction in Animals Notes - Reproduction in Animals

Reproduction in Animals

·                     Reproduction is the biological process by which an individual organism gives birth to its young one. Animals can reproduce by two modes ?

·                     The mode of reproduction in which an individual can reproduce without involvement of another individual of that species is called asexual reproduction.

·                     Sexual reproduction is the type of reproduction in which two individual, called parents, are needed to reproduce the young ones.

·                     Human male reproductive system consists of a pair of testes (singular testis), two sperm ducts and a penis.

·                     Human female reproductive system consists of a pair of ovaries, oviducts (fallopian tubes) and the uterus.

·                     The testes produce male gametes called sperms and the ovary produces female gametes called ova.

·                     In sexual reproduction, male gamete fuses with female gamete. The fusion of ovum and sperm is called fertilization and the fertilized egg is called a zygote.      

·                     The zygote divides repeatedly to give rise to an embryo which gets embedded in the wall of the uterus for further development.

·                     The stage of the embryo in which all the body parts are identifiable is called foetus.

·                     Fertilization that takes place inside the female body is called internal fertilization. This type of fertilization is observed in human beings and other animals such as hens, cows and dogs.

·                     Fertilization that takes place outside the female body is called external fertilization. This type of fertilization is observed in animals like frogs, fish, starfish, etc.

·                     Animals which give birth to their young ones are called viviparous animals. Human beings, cows and dogs are some examples or the viviparous animals.

·                     Animals which lay eggs are called oviparous animals. For example, hen, frog, lizard and butterfly etc.

·                     Some animals physically develop after birth or hatching, involving a conspicuous and relatively abrupt change in their body structure through cell growth and differentiation. This transformation of the larva into adult through drastic changes is called metamorphosis.

·                     Binary fission and budding are some of the methods of asexual reproduction, Hydra reproduces by budding and amoeba reproduces by binary fission.