New Terms:
Calyptra (root cap): The root cap is located at the very tip of the root and is also called the "calyptra." The calyptra acts as a "hard hat" and protects other cells from damage.
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apical meristem: The part of the plant responsible for new cells.
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statocytes: The part of the plant cells that are thought to be responsible for gravitropism.
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Main Functions of the Root System
Anchor
Roots act as anchors and help the plant stay upright.
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AbsorbRoots absorb water and minerals from the soil.
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Store
Roots serve as storage for the nutrients produced by the plant.
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TransportRoots form a passage way for water and dissolved substances from the root into the stem and also for foots from the stem back down to the root (botany).
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In plants, the main function of the calyptra is to protect the other root tissues from damage as the root grows and pushes through the soil. It acts as the "hard hat" in a construction site protecting more vulnerable cells.
The calyptra looks like the top of a thimble and can easily be distinguished under a microscope.
The calyptra looks like the top of a thimble and can easily be distinguished under a microscope.
Meristematic Region
Apical Meristem
Located directly behind the root cap is the apical meristem, and is directly responsible for the creation and division of new cells. This is located within the meristematic region.
New cells go through two stages: creation (mitosis) and expansion. Once cells are created they expand as they begin to store more water. |
Meristem Structure
Protoderm
The protoderm forms the outer dermal layer of tissues.
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Ground Meristem
The ground meristem which forms the cortical cells.
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Procambium (provascular tissue)
The procambium is the primary tissues which are elongated and are used in the vascular system.
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Zone of Mitosis
Often referred to as the quiescent center, the zone of mitosis is where the cells are actively dividing. In this zone is where you can observe the cell division process: mitosis.
During this phase, the nucleus is evenly divided between two cells. Once the process is complete, two daughter cells with identical genetic material are produced (biology). |
Meristematic Cells Divide by MitosisThe actively dividing cells are called meristematic cells.
Interphase
Chromatin is a mass of genetic material composed of DNA and proteins that condense (come together) to form chromosomes. The chromatin is located in the nucleus of the cell. |
Prophase
During the prophase, the chromatin condenses (comes together) and becomes visible as new chromosomes are formed. The nucleolus disappears and the nuclear membrane fragments.
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Metaphase (After Phase)
Chromosomes line up along the metaphase plate (imaginary line), and spindle fibers become attached to the chromosomes.
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Some of the new cells are directly added to the calyptra (root cap) and other cells are directly added to the zone of elongation.
The calyptra also contains statocytes and is thought to be responsible for gravitropism in plants. Gravitropism helps plants sense gravity so that they can grow their roots deeper into the ground. If the calyptra was carefully removed, the plant roots would grow in every direction.
Koning, Ross E. 1994. Roots. Plant Physiology Information Website. http://plantphys.info/plants_human/roots/rootlec.shtml. (6-22-114).