Changes
From Karnataka Open Educational Resources
120 bytes added
, 17:18, 1 August 2014
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| http://www.tantebazar.com/imgx/simple_plant_tissues.jpg | | http://www.tantebazar.com/imgx/simple_plant_tissues.jpg |
| + | '''Figure showing differences between parenchyma,collenchyma and sclerenchyma tissue''' |
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− | DERMAL TISSUE:<br> | + | '''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> | + | 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 cutin 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> | + | 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> | | 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> | + | 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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− | http://www.bbc.co.uk/schools/gcsebitesize/science/images/bi05004.gif<br> | + | http://www.bbc.co.uk/schools/gcsebitesize/science/images/bi05004.gif |
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− | Cross section of a leaf showing epidermis | + | '''Cross section of a leaf showing epidermis''' |
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| ===Activities=== | | ===Activities=== |