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Ch. 8: Roots - Coggle Diagram
Ch. 8: Roots
Root Structure
Mucigel- Dictyosomes of root cell cap cells secrete a complex polysaccharide. This lubricates the passage of the root through the soil.It also causes the soil to release its nutrient ions and permits the ions to diffuse more rapidly toward the root. Rich in carbohydrates and amino acids, which foster rapid growth of soil bacteria around the root tip.
Zone of elongation- Located right behind the root cap and root apical meristem. Only a few millimeters long within which the cells undergo division and expansion.
Root Hair Zone- Behind the zone of elongation. A region in which many of the epidermal cells extend out as narrow trichomes.
Root Hairs- form only in a part of the root that is not elongating, otherwise they would be shorn off. These greatly increase the root's surface area.
Function for only several days, then they die and regenerate.
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Root Strips- Absorption of minerals in the root hair zone causes a powerful absorption of water, and a water pressurebuilds up.
if not for the mature endodermis, root pressure would force the water to leak out into the shoot. If water leaks into the stem cortex and filled intercellular spaces, oxygen diffusion would be prevented and the tissues would suffocate.
prop roots- Any of the modified roots that arise from the stem of certain plants and provide extra support. Such stems are usually tall and slender and the prop roots develop at successively higher levels as the stem elongates, as in the maize plant.
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Soil
On a microscopic level, soil contains sand grains, crystals, and other components that can damage the delicate apical meristem and root cap. Cell multiplication is a big component of root growth since the cap is worn away in this process.
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Root Hair
Root hair grows outward, greatly increasing absorption of water and minerals.
The zone of elongation merges gradually with the zone of maturation; no distinct boundary exists because the differences between the two represent the gradual continued differentiation of the cells.
Cortex cells- continue to enlarge, their most significant activity is transfer of minerals from the epidermis to the vascular tissue. This can either be by diffusion through the walls and intercellular spaces by absorption into the cytoplasm of a cortical cell and then transferal from cell to cell, probably through plasmodesmata.
mycorrhizae
a fungus which grows in association with the roots of a plant in a symbiotic or mildly pathogenic relationship.
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