Students can go through AP Inter 1st Year Botany Notes 7th Lesson Sexual Reproduction in Flowering Plants will help students in revising the entire concepts quickly.
AP Inter 1st Year Botany Notes 7th Lesson Sexual Reproduction in Flowering Plants
→ Flower is a modified shoot meant for sexual reproduction.
→ In a flower, Androecium is the male reproductive organ and Gynoecium is the female reproductive organ.
→ A typical angiospermic anther is bilobed with each lobe having two theca called Dithecous Anther.
→ The anther of Hibiscus is single lobed and is known as monothecous Anther.
→ The Anther is a four sided structure consisting of four Microsporangia located at the corners, two in each lobe.
→ Each microsporangium appears circular and is surrounded by four wall layers, the epidermis, endo- thecium, middle layers and tapetum.
→ The tapetum nourishes the developing pollengrains.
→ The sporogenous tissue undergo meiosis to form Microspore tetrads called Microsporogenesis.
→ Pollengrains are spherical, covered by two layered wall (exine) outerlayer is made up of sporopollenin and inner layer. Intime is made up of pectin and cellulose.
→ In over 60% of angiosperms, pollengrains are relea¬sed at two celled stage (The larger vegetative and the smaller Generative cell).
→ In the remaining 40% of angiosperms, pollengrains are released at three celled stage (Two male gametes and one vegetative cell).
→ In western countries, pollengrains are used in the form of tablets and syrups because of rich nutrients.
→ The stigma serves as a landing platform for pollengrains.
→ In Loranthus – ovules are not covered by integuments.
→ In Helianthus & Datura, the ovules are unitegmic.
→ In polypetalous members and Monocots, the ovules are bitegmic.
→ In polygonum, the micropyle, chalaza and funicle lie on the same plane called Orthotropous ovule.
→ In Sunflower, the body of the ovule bends at an angle of 180° so called anatropous ovule.
→ In Bean family, the body of the ovule bends like a kidney shape called campylotropous ovule.
→ The formation of megaspores from the megaspore mother cell is called mega- sporogenesis.
→ 7 – celled and 8 nucleated embryo sac is formed from single megaspore celled mono- sporic embryosac.
→ Embryosac contains egg apparatus, antipodals and two polar nuclei.
→ Transfer of pollengrains from anther to stigma is called pollination.
→ Transfer of pollengrains from anther to stigma of the same flower is called self pollination or pollengrains transfer to the stigma of another flower is called cross pollination.
→ Pollination by wind is called anemophily.
→ Pollination by water is called hydrophily.
→ Pollination by animals is called zoophily.
→ Pollination by birds is called ornithophily.
→ Pollination by bats is called chiropterophily.
→ Pollination by squirrels is called therophily Pollination by reptiles is called ophiophily.
→ In sunflower protandrous condition favours cross pollination.
→ In Datura, Solanum, Protogynous condition favours cross pollination.
→ In Hibiscus, the Anther and stigma are placed at different heights called Herkogamy. In Abutilon, self sterility or self. Incompatibility is common.
→ Male and female flowers are present on the same plant, that is called monoeciuous condition.
Ex : Castor, Maiza.
→ Male and female flowers are present on different plants called Dioecious condition.
Ex : Papaya.
→ The pistill has the ability to recognise the pollen and accepts the pollen.
→ The pollen tube enters into the ovule either through Micropyle or chalaza or through Integuments.
→ Removal of Anthers from female parent of a bisexual flower is called musculation.
→ The emusculated flowers are covered with polythene Bags to prevent contamination is called Bagging.
→ One male gamete fuses with Egg to form Zygote (syngamy). The second male gamete fuses with secondary nucleus to form primary endosperm nucleus (Tripple fusion)
→ The zygote develops into globular heart shaped mature embryo.
→ Production of seeds without fertilization is called apomixis.
→ Production of fruits without fertilization of ovary is called parthenocarpy.
→ Occurrence of more than one embryo in a seed is called polyembryony.
→ Allogamy : Transfer of pollengrains from one flower to another.
→ Anemophily : Pollination by wind.
→ Autogamy : Transfer of pollen grains within the same flower.
→ Antipodals : Three cells present in the embryosac towards chalaza.
→ Apomixis : Production of seeds without fertilisation.
→ Chasmogamy: Pollination occurring in an opened flower,
→ Chiropterophily: Pollination by bats.
→ Cleistogamy : Pollination occurring in a closed flower.
→ Clone : Morphologically and genetically similar individual produced through means other than sexual reproduction.
→ Chalaza : Basal portion of the nucellus in the ovule from which the integuments appear.
→ Chalazogamy : Entry of pollen tube into embryosac through chalaza of the ovule.
→ Coleorhiza : Undifferentiated sheath of embryonal axis enclosing radicle and root cap.
→ Coleoptile : Hollow foliar structure of epicotyl, that encloses plumule.
→ Dichogamy : Ripening of anthers ;and stigma in a flower at different times.
→ Dioecious : Male and female flowers on different plants.
→ Doublefertilization : Two fusion processes (a) one male gamete + egg cell (b) second male gamete + secondary nucleus; characteristic feature of angiosperms.
→ Entomophily : Pollination by insects
→ Egg apparatus : Three cells present in the embryosac towards micropyle.
→ Embryo : Miniature plant consisting of axis (plumule, radical) and cotyledons enclosed in the seed coat.
→ Embryology: Branch of science which deals with development and formation of gametes, ‘ process of fertilisation and development of embryo.
→ Embryosac : Female gametophyte containing egg apparatus, secondary/ polar nuclei and antipodals ; in angiosperms mostly 7 celled (8-nucleate).
→ Endosperm : Nutritive tissue for the developing embryo; in angiosperms it is a triploid tissue.
→ Endothecium : The layer below the epidermis in anther wall with fibrous bands on tangential walls, which help in dehiscence of anther.
→ Fertilization ; Fusion of male gamete with the egg cell.
→ Floriculture : Cultivation of flower yielding plants.
→ Funicle : Stalk of the ovule.
→ Gametophyte : Plant body with haploid cells producing gametes.
→ Geitonogamy : Transfer of pollen grains from one flower to another of the same plant.
→ Herkogamy : Anthers and stigma at different heights or in different directions.
→ Heterogametes : Two morphologically distinct gametes (male and female).
→ Homogamy : Anthers and stigma of a flower ripen at the same time.
→ Hydrophily : Pollinai.on by water.
→ Integuments : Multicellular coats Protecting the nucellus in the ovule.
→ Isogametes (Homogametes) : Two Gametes are similar in structure and function.
→ Juvenile Phase : The stage of growth and maturity.
→ Malacophily : Pollination by snails.
→ Monoecious : Male and female flowers on the same plant.
→ Megaspore : Haploid cell, developing into female gametophyte or embryosac.
→ Mesogamy : Entry of pollen tube through base of ovule or through funicle or integuments.
→ Micropyle : An opening into the ovule where integuments do not enclose the nucellus.
→ Microspore : Pollen grain developing into male gametophyte (3-celled). .
→ Nucellus : Mass of thin walled parenchymatous tissue inside the ovule.
→ Ornithophily : Pollination by birds.
→ Ovule : Megasporangium in flowering plants.
→ Pericarp; The outer wall of a fruit.
→ Perisperm: The persistent residual nucellus.
→ Pollen Bank : It is a collection of pollen grains in viable state of posterity. Pollen banks are important, as it can made available pollen for breeding experiments, and for raising haploid plants.
→ Pollen/Nectar robbers : Insects which consume pollen or nectar without helping in pollination.
→ Pollination : Transfer of pollen grains from anther to stigma.
→ Pollinators : Agents which help in pollination.
→ Protandry : Ripening of anthers earlier than stigmas of same flower.
→ Protogyny : Ripening of stigma earlier than anthers of same flower.
→ Polyembryony : Development of more than one embryo, in the same seed.
→ Porogamy : Entry of pollen tube through the micropylar end of the ovule.
→ Primary Endosperm Nucleus : Triploid nucleus formed by the union of second male gamete and fusion product of two polar nuclei.
→ Raphe : Part of funicle in an inverted ovule, which remain attached beyond hilum along side of the body of ovule.
→ Scutellum : Cotyledon of Monocots (Grass Family).
→ Secondary Nucleus : Fusion product of two polar nuclei.
→ Seed bank : It is a collection of seeds in a viable state of posterity. It is one of the most efficient methods of ex-situ conservation for sexually reproducing species.
→ Self sterility : Inability of pollen grains to-germinate on stigma of the same flower.
→ Sporophyte : Plant body with diploid cells producing haploid spores by meiosis in spore mother cells.
→ Synergids : Two cells present on either side of egg in egg apparatus.
→ Tapetum : Inner most wall layer of anther nourishing the developing microspores.
→ Vivipary : The seeds germinate while they are still attached to the mother plant.
→ Xenogamy : Transfer of pollen grains from one plant to another of the same species.
→ Zoophily : Pollination by animals.
→ Zygote : Diploid cell formed by the fusion of male and female gametes.