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 this p
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Structure of Dicotyledonous Albuminous Seeds-digieduco

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Structure of Dicotyledonous Albuminous Seeds : 

I. CASTOR SEED (Ricinus communis, Euphorbiaceae)-
(a) Seed coat consisting of hard brittle crustaceous blackish or brownish testa with caruncle which is a fleshy outgrowth at the micropyiar region ; hilum is hidden by the caruncle. Distinct longitudinal raphe is present in the centre. Tegmen is absent-the thin membranous covering over the kernel as seen on removing outer hard testa is the perisperm.

Structure of Dicotyledonous Albuminous Seeds-digieduco

(b) Kernel-It is the white fleshy mass as seen on removing the testa. It consists of a thin papery white perisperm and fleshy whitish mass-the endosperm. In the centre of this endosperm, a large straight embryo is embedded. The embryo has two thin leaf-like cotyledons and a short axis in which plumule and radicle with short hypocotyl are distinguished. The plumule is hidden in between the cotyledons.

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