How to draw internal structure of скачать в хорошем качестве

How to draw internal structure of

ABOUT VIDEO: The internal structure of a dicot root can be studied from transverse section of a young root of sunflower, gram and pea. The arrangement of tissues from the periphery to the centre are; 1. Epdermis: it is the outermost single layer. It is composed of thin- walled, closely packed parenchymatous cells without intercellular spaces. Unicellular root hairs are present. 2. Cortex: It consists of many layers of thin walled rounded or polygonal parenchymatous cells. Cotex cells store food and conduct water from epidermis to the inner tissues. 3. Endodermis: It is the innermost layer, made up of a single layer of barrel shaped compact parenchyamatous cells without intercellular spaces. Cells of endodermis lying opposite the protoxylem elements are thin walled and known as passage cells because they allow the passage of water from roots to the xylem. Other thickened parts in the cells of endodermis is casparian stripe. 3. Pericycle: It composed of single layer of thin walled parenchymatous cells containing abundant protoplasm. 5. Conjunctive tissue: The parenchyma lying in between xylem and phloem bundles constitutes the conjunctive tissue. 6. Vasculare bundles: It is radial type. These are arranged in an ring, xylem and phloem form an equal number of separate bundles placed on different radii. a) Xylem: It appears conical in shape and are thick walled. Protoxylem lies towards the periphery, so the xylem is exarch. Xylem parenchyma and fibres are absent and a few tracheids are present around the vessels. b) Phloem: It lies alternate to xylem patches. The patches are smaller and consists of sieve tubes, companion cells and phloem parenchyma. The phloem fibres are absent. The outerpart of this tissue next to pericycle is the protophloem and inner is the metaphloem. 7. Pith: It occupies small area in the centre and consists of a few compactly arranged, thin- walled parenchymatous cells without any intercellular space. #Please#Subscribe