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Ch 8: Roots, Screen Shot 2021-03-29 at 9.30.17 AM - Coggle Diagram
Ch 8: Roots
Most roots have three functions:
- Anchoring the plant firmly in place.
- Absorbing water and Materials.
- Producing hormones.
In many cases, roots have functions in addition to or instead of anchoring, absorption, and hormone production. Taproots such as these in carrots and beets is the main storage site of carbohydrates during the winter months.
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A Prop Root is any root that grows through air or water before entering the soil. These help to stabilize the plants shoot.
Butteress Root is a root that grows asymmetrically to where it becomes very tall and thin. These can extend up the truck as much as a meter and gives the trunk lateral stability.
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Root Apical Meristem the set of cells capable of dividing, located at the apex of the root. Produces the root itself and also the root cap.
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The Endodermis is a sheath of cells surrounding the vascular tissue of roots (And occasionally horizontal stems). Their Casparian strips prevent uncontrolled diffusion between root cortex and root vascular tissue by means of walls and intercellular spaces.
Casparian Strips are a layer of impermeable login and Suberin in the walls of endodermal cells, preventing diffusion of material through that portion of the wall.
Root Pressure ia the water in the root xylem is under pressure due to the active accumulation of salts by the endodermis and the accompanying influx of water.
Passage Cells are cells in the endodermis that has only Casparian strips whereas all surrounding endodermis cells have thickened waterproof walls.
Nitrogen Fixation is the conversion of atmospheric nitrogen into any compound plants can use. These are typically either nitrate or ammonium.
During the invasion of roots by nitrogen fixing bacteria, the bacteria are encased in an invagination of the plants cell walls causing an Infection Thread
Root Nodule Several species of plants have a symbiotic relationship with nitrogen fixing bacteria. In some species, especially legumes, these become swollen and occupied by bacteria.
Mycorrhizae are fungi that form a symbiotic relationship with the roots of plants. These usually benefit the plant because they provide phosphorus.
An. Ectomycorrhizal Relationship exists to where the fungal hyphae penetrate between the outermost root cortex cells but never invade the cells themselves.
Endomycorrhizal Association is when the hyphae penetrate the root cortex as far as the endodermis. These can pass through the walls of the cortex but can't pass the Casparian Strips.
The Haustoria is a modified root and is a structure where a parasite draws nutrients from the plant. In fungi it is a Hypha.
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