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 Monocotyledonous Albuminous Seeds-digieduco

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Structure of Monocotyledonous Albuminous Seeds : 

I. MAIZE GRAIN - Maize grains are flat and oblong. These are actually one-seeded fruit. Here the outer covering of the seed is the fused seed coat and the non-separable pericarp. Hilum and micropyle are not visible due to the pericarp covering.

Structure of Monocotyledonous Albuminous Seeds

Embryo is situated on the flat face within the whitish deltoid area. It consists of (i) single shield-shaped cotyledon known as scutellum and (ii) an axis differentiated into Upper plumule covered by coleoptile or plumule sheath and the lower radical covered by coleorhiza or radicle sheath.

Endosperm is the food storage tissue separated from the embryo by a layer known as epithelium. The upper horny part of the endosperm away from scutellum (i. e. the single cotyledon) contains protein, while the lower mealy part of the endosperm nearest to the scutellum contains starch.

ll. RICE GRAIN (Oryza sativa, Gramineae)-

It is also a small one-seeded fruit. The grain is provided with a brownish wall made up of seed coat and the non-separable pericarp fused together.
Structure of Monocotyledonous Albuminous Seeds

Endosperm is starchy which occupies the major portion of the grain-it is separated from the embryo by an epithelial layer.

Embryo is small and situated at one end of the endosperm. Like maize it also consists of (i) one shield-shaped cotyledon known as scutellum and (ii) a short axis, the upper part representing the plumule surrounded by minute leaf-sheath or coleoptile and the lower radicle protected by root cap and surrounded by root-sheath or coleorhiza. A small projected structure known as epiblast, is seen opposite to scutellum.

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