LO 1.2 - Roots Flashcards
- Function: primary and secondary - True and adventitious - Tap and fibrous - Anatomy: Rootcap, epidermis, cortex and stele - Modifications: aerial, stilt and tuberous
Question
What are the Key functions of Roots?
Name 4 things.
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- Anchorage
- Absorption
- Storage
- Growth
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Question
What is Anchorage?
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Roots anchor plants firmly in the ground and provide support for vertical growth.
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Question
What is Absorption?
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Water and nutrients such as minerals are absorbed by roots and transported through the plant to the locations where they are needed.
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Question
What is Storage?
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Many plant species use roots as a storage organ, primarily for carbohydrates.
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Question
What is Growth?
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Dividing cells in the root cap are responsible for the elongation of root.
(Primary growth)
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Question
What are some secondary functions of Roots?
4 things
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- Prevent soil erosion.
- Mechanical support.
- Climbing.
- Nitrogen Fixation.
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Question
How do roots prevent soil erosion?
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Prevent soil erosion – roots help hold the soil matrix firmly.
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Question
How do roots give mechanical support?
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Mechanical support - Roots can provide stability to the plant.
Eg, In Maize and sugarcane stilt roots developed on the lower part of node which provide mechanical support to the plant.
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Question
How do roots help in climbing?
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Climbing – roots can help weak stemmed plants to cling and climb. Example Ivy
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Question
What is Adventitious Root?
Define it, remember it.
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Adventitious root
Roots that grow from the stem base / also formed on cuttings.
They do not develop from the radical of the seed.
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Question
What are Fibrous roots?
Define it, remember it.
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Fibrous roots
Are a fine network of branching roots.
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Question
What are Lateral roots?
Define it, remember it.
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Lateral roots
Grow out at right angles from parent root.
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Question
What is the Primary root?
Define it, remember it.
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Primary root
First roots that grow from the seed.
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Question
What are Root hairs?
Define it, remember it.
Roots
Root hairs
Single celled ext of the epidermal cells, close to the growing root tip.
Roots
Video
Root hairs in detail.
1 minute watch.
Root Hairs
* Root hairs exist so plants can take up more water/minerals .
* They consist of a nucleus, large vacuole, cytoplasm and mitochondria.
* No chloroplast – So no photosynthesis takes place in the roots.
Click for a 1 minute watch.
Question
What are Tap roots?
Define it, remember it.
Roots
Tap root
* Where a plant has just one large fleshy root that is significantly larger than any lateral roots.
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Info Graphic
Adventitious Roots
This example in Strawberries.
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Adventitious Roots
In Strawberries.
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Info Graphic
Tap Roots vs Adventitious Roots
Comparing Tap to Adventitious roots.
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Tap Roots vs Adventitious Roots
Comparing Tap to Adventitious Roots.
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Question
Stolons are not part of the root system.
So what are Stolons?
Roots
Stolons
* Are horizontal connections between organisms.
* They are a **stem NOT a root **that produce nodes from which new plants form.
Example in Strawberries, Runners are Stolons.
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Info Graphic
Stilt Roots on Maize
Stilt Roots on Maize
Info Graphic
Tuberous Roots
Roots
Tuberous Roots
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Question
What are Tuberous Roots?
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Tuberous root
Is an enlarged fleshy root modified as a storage organ with shoots produced at one end and roots produced at the other.
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Info Graphic
Don’t confuse Tuberous roots with other Storage Roots.
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Potatoes and Dahlia’s are Tuberous
Bulbs, Carrots, Onions and Beetroot are not.
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Question
What are Aerial Roots?
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Aerial roots are roots that are above ground. They are grown for support. Ivy plants have them to cling to structures, such as stone walls, or other trees.
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What are the functions of these roots?
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Storage.
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Study card.
Rootcap
Reveal for 5 bullet points.
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Rootcap
* At the tip of every growing root is tissue called the root cap.
* It is not visible to the naked eye.
* It consists of tissue (parenchyma) with unthickened walls covering the apical meristem.
* The root cap provides protection to the meristem cells as the root goes through the soil.
* Cells can ware away but are quickly replaced by new cells generated by cell division within the meristem.
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Study Card
Root Epidermis
Reveal for 5 bullet points.
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Root Epidermis
* The root hairs of the epidermal cells increase the surface area through which movement of materials can occur.
* The thread like hairs are simply enlargements of the protoplast that extend outward into the soil.
* They have little wall material and are extremely fragile and easily broken.
* It is the outer layer and it forms a boundary between the plant and the environment.
* It protects against water loss, regulates gas exchange, absorbs water and minerals.
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Study Card
Cortex
Reveal for 4 bullet points.
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Cortex
* Made of parenchyma cells.
* Is the largest part of the primary root.
* Three layers of cortex are recognized: the hypodermis (also called exodermis), the endodermis and, between them, the storage parenchyma.
* Its function is transportation of material and also may be used as a food store.
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Study Card
Stele
Reveal for 3 bullet points.
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Stele
* The stele includes all of the tissues within the cortex.
* The pericycle - a cylinder of parenchyma.
* The vascular tissues—xylem and phloem on the inside in the roots.
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