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Published byJohnathan Poole Modified over 9 years ago
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Plant Tissues Plant structures are composed of 4 main tissues. They are: Epidermis – outer layer of cells which protect the plant from water loss and from fungi and bacteria Vascular Tissues – transport water, sugars and other materials through the plant Ground Tissues – tissues that the vascular tissue is embedded in…. usually storage cells Meristematic – cells that divide
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Plant Tissues Meristematic- growth Epidermal- protection
Parenchyma- storage Sclerenchyma- strengthen and support Vascular- transportation xylem = water + nutrients phloem = plant products in solution
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Plant Tissues
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In Most Plants Glucose is produced in the leaves through photosynthesis. The glucose is converted to sucrose (by dehydration synthesis) for transportation. The sucrose is converted to starch and stored.
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Roots Roots have many functions.
1. anchor the plant 2. bind soil… stops erosion 3. absorb water and minerals 4. store food (usually as starch)
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Root Types
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Taproots look large and fleshy,
are mostly found in plants with two seed-leaves (dicots), grow deep into the ground to search for food, are able to store food, which is particularly necessary for perennial plants during periods of dormancy.
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Fibrous roots lie close to the surface of the soil,
are mostly found in plants with one seed-leaf (monocots) collect precipitation before it sinks deep into the ground, can often be found growing side by side with taproots- the two types of roots combine efforts to maximize efficiency.
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Adventitious roots are common in both dicots and monocots
develop to help the plant climb: for example, ivy help develop modified underground stems, such as bulbs
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Aerial Roots modified to absorb water from the air
Aerial roots of an Orchid Orchids in bloom
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Root Hairs are actually epidermal cells adapted to absorb water
* Water enters the cells by Osmosis * Minerals enter by Active Transport
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Regions of the root tip Region of Maturation - Most cells differentiate into various distinctive cell types. Root hairs form. Region of Elongation - Cells become several times their original length. Vacuoles merge Region of Cell Division - Composed of apical meristem in the center of the root tip. Most cell division occurs at the edge of the inverted cup-shaped zone. Root Cap - Thimble-shaped mass of parenchyma cells covering each root tip. Protects tissue from damage. Function in gravity perception.
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The Root Tip
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The Function of Root Tissues
Epidermis – outer layer of cells, provide protection from drying out, water loss and infection. Cortex – area made up of parenchyma cells. Parenchyma cells are usually storage cells Endodermis – regulates materials entering the center of the root. Pericycle –the outermost layer of cells of the stele Xylem – transports water Phloem – transports sugar Stele – Also known as the “Vascular Cylinder”…… made up of the xylem and phloem Pith – tissue located in the center of the stem Apical Meristem - (Meristematic Tissue) – tissue that in a constant state of growth… apical means “located at the tip” Meristem accounts for the increase in length of the roots and stems.
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Dicot Root X-section
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Monocot root X-section
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Dicot root X-section Most Dicot roots have an “X” of xylem cells in the center of the root.
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The Casparian Strip regulates the movement of water into the root
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Stele
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