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Organisation of cells plant tissues (view source)
Revision as of 21:11, 1 August 2014
, 21:11, 1 August 2014→Notes for teachers
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DERMAL TISSUE:<br>
The outermost covering of all parts of plant-stem,leaves,flowers,fruits,seeds and roots- is formed by protective tissue called Dermal tissue.The epidermis is usually made of a single layer of cells. In some plants living in very dry habitats, the epidermis may be thicker since protection against water loss is critical. The entire surface of a plant has this outer covering of epidermis. It protects all the parts of the plant.Epidermal cells on the aerial parts of the plant often secrete a waxy, water-resistant layer on their outer surface. This aids in protection against loss of water, mechanical injury and invasion by parasitic fungi.<br>
We can observe small pores here and there in the epidermis of the leaf. These pores are called stomata. Stomata are enclosed by two kidney-shaped cells called guard cells. They are necessary for exchanging gases with the atmosphere.Transpiration (loss of water in the form of water vapour) also takes place through stomata.<br>
Epidermal cells of the roots, whose function is water absorption, commonly bear long hair-like parts that greatly increase the total absorptive surface area.<br>
In some plants like desert plants,cabbage,banana etc. epidermis has a thick waxy coating of cutin on its outer surface to prevent water loss.<br>
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===Activities===
===Activities===
