Cell membrane function and difference-digieduco

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  Functions of cell membrane : (a) The proteins and enzymes present in the cell membrane helps in the transport of certain substances like sugar, sodium and other ions etc. across the cell membrane. (b) Cell membrane protects the internal structures of the cell and different organelles of the cytoplasm. (c) It maintains the shape of the cell. (d) It acts as a selective permeable membrane because it allows to pass certain substances while others are not, hence it helps in the transport of selective materials from and to the cells. (e) The membranes on the cytoplasmic organelles and nucleus most probably formed from the plasma membrane. (f) Other important functions of cell membrane of the cells are endocytosis and exocytosis . Endocytosis is the process by which materials are transported into the cells by the formation of vesicles. It includes two processes-phagocytosis (cell eating) and pinocytosis (cell drinking). The reverse process of endocytosis is exocytosis. During th...
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Contrivances for Self-pollination-digieduco

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The Contrivances for Self-pollination are cleistogamy and hypogamy. They are discussed in details below:-

(1) CLEISTOGAMY-Various types of adaptation in cleistogamous flowers belonging to different families are met with. In Viola sp. (Violaceae) there are apetalous flower or flowers havin g small petals in which anthers are closely applied to the stigma by bending of filaments. Cleistogamy is also observed in the underground flowers cf Commelina benghalensis (Commelinaceae)these flowers are minute and inconspicuous, they never open from bud condition. But brightly coloured (blue or violet) aerial flowers of Commelina benghalensis are insect pollinated (chasmogamousduring anthesis the flowers open normally). Cleistogamy often occurs in species of Impatiens (Balsaminaceac). Cardamine (Cruciferae), Halenia (Gentianaceae) etc.
Contrivances for Self-pollination-digieduco

(2) HOMOGAMY-It is the condition of the maturity of anthers and stigmas at the same time.-so that self-pollination is effected, although not always. pollen grains are taken to the stigma by some agents like wind, insects etc. Homogamy is seen in Opuntia dillenii (Cactaceae), Microcos asiatica (Tiliaceae),Argemone mexicana (Papaveraceae),  etc. In Mirabilis sp. (Nyctaginaceae), selfpollination is favoured as the filaments are brought to the contact of the stigma by curling and twining of the same. 

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