RBSE Class 12 Biology Notes Chapter 1 Reproduction in Organisms

These comprehensive RBSE Class 12 Biology Notes Chapter 1 Reproduction in Organisms will give a brief overview of all the concepts.

RBSE Class 12 Biology Chapter 1 Notes Reproduction in Organisms

→ Reproduction : Reproduction is a biological process by which an organism produces another organism (offspring) similar to itself.

→ Reproduction is necessary for the continuity of the species. All the reproductive methods are broadly categorised into two types : Asexual reproduction and Sexual reproduction.

→ Asexual reproduction : It is the production of offsprings by a single parent and is does not involve gametic fusion.

→ Asexual reproduction is common in unicellular organisms such as algae, fungi, protozoans and some invertebrates.

→ The various methods of asexual reproduction are : Fission, Budding, Fragmentation, Regeneration. Spore formation and vegetative propagation.

→ Most of the prokaryotes (e.g., Bacteria) and unicellular protists (e.g,, Amoeba, Paramecium) reproduce by binary fission.

→ Budding is common in yeast and Hydra.

→ Multiple fission is common reproducing method for Amoeba and Plasmodium.

→ Fragmentation mathod of asexual reproduction is very common in algae (e.g., Spirogyra) and Fungi (e.g., Vaucheria).

→ Regeneration is most commonly shown in Planaria.

→ Spore formation is the most common means of asexual reproduction in algae and fungi. The main types of spores are zoospores, sporangiospores, conidia, gemmules, chlamydospores and oidia.

→ Vegetative reproduction : It is a mode of reproduction in which new plants are formed from vegetative parts of the plant like roots, stems, leaves etc.

→ Vegetative reproduction is of two main types : Natural vegetative reproduction and Artificial vegetative reproduction.

→ The natural methods of vegetative reproduction involve some specialised structures namely, runners, suckers, rhizome, tubers, corm, bulbs, stolon, offset etc.

→ Artificial methods of vegetative reproduction have been developed by plant growers and Horticulterists for commercial production of economically important plants. These methods include : cutting, grafting, layering, bud grafting and micropropagation.

→ Vegetative propagation is the only method of reproduction in plants which have lost their capacity to produce seeds.

→ Sexual Reproduction : Sexual reproduction is the production of offsprings by the formation and fusion of specialized male and female cells, called gametes.

→ There are three events of sexual reproduction : Pre-fertilization events (It includes formation of zygote and embryogenesis). It includes gametogenesis and gamete transfer. Fertilization (it is also known as syngamy) and post-fertilization events. (It includes formation of zygote and embryogenesis).

→ Fertilization is the fusion of male and female gametes to form a diploid cell called zygote.

→ The phenomenon of development of female gamete directly into an individual without fertilization is called parthenogenesis.

→ Based on whether the zygote develops outside the body of female parent or inside, animals can be classified into oviparous and viviparous respectively.

→ Reproduction : Process by which an organism produces another organism.

→ Life-span : The period from birth to the natural death of an organism.

→ Asexual reproduction : Production of offspring by a single parent and it does not involve gametic fusion. Haploid : The condition of cell/organism in which only one set of chromosomes is present. 

→ Diploid : The condition of cell/organism in which pairs of chromosomes are present.

→ Clone : The exact copy of parent is called clone.

→ Binary fission : The splitting of a parental cell into two equal daughter cells, is called binary fission.

→ Multiple Fission : The splitting of a parent cell into numerous daughter cells is called multiple fission.

→ Sporulation : The formation of spores to reproduce offsprings is called sporulation.

→ Regeneration : A process in which the missing part of an organism is repaired by proliferation of cells.

→ Zoospores : Endogenously produced unicellular, naked and motile spores.

→ Conidia : Asexual, non-motile spores cut off externally either singly or in chains.

→ Gemmules: Internal asexual reproductive units or buds.

→ Vegetative propagation : A mode of reproduction in which new plants from vegetative part of parent plant.

→ Sexual reproduction : A method of reproduction which involves the fusion of male and female gametes to form a zygote.

→ Gamete : Haploid sexual cell, such as sperm or egg.

→ Gametogenesis : The process of formation of garnets (i.esperms and ova) is called gametogenesis.

→ Oestrous cycle : Characteristic cyclic changes start in non-primate females.

→ Menstrual cycle : Characteristic cyclic changes start in female primates.

→ Monoecious : An individual which can produce both male and female gametes is called monoecious, bisexual or hermaphrodite.

→ Dioecious : An individual which produce only one kind of gametes, is called dioecious or unisexual.

→ Pollination : Transfer of pollen grains to stigma.

→ Zygote : Diploid cell, produced by the fusion of two haploid gametes.

→ Embryogenesis : Development of young one from zygote.

→ Oviparous : Animals which lay egg.

→ Viviparous: Animals which give birth to young ones.

→ Parthenogenesis : Development of embryo from unfertilized female gamete called parthenogenesis.