Back to AI Flashcard MakerAnatomy and Physiology /OCR Biology A - 3.1.3 - Transport in Plants Part 2
OCR Biology A - 3.1.3 - Transport in Plants Part 2
This deck covers key concepts related to the transport mechanisms in plants, focusing on root hairs, meristems, water uptake, transpiration, translocation, and more.
Purpose of root hairs
Provide a very large surface area for uptake of water and ions
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Key Terms
Term
Definition
Purpose of root hairs
Provide a very large surface area for uptake of water and ions
Why is the root tip covered by a cap of cells
Protects dividing cells of the top and lubricates root movement
Meristem in roots
Increase height of plants
Meristem in stem
Increase plant girth
Stele
Section in middle of transverse section of dicotyledonous root Endodermis Xylem tissue Phloem tissue
Water uptake
Water enters capillaries from soil (osmosis) Apoplast and symplast pathways (root hair cells to cortex) Water leaves apoplast at endodermis and enter ...
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| Term | Definition |
|---|---|
Purpose of root hairs | Provide a very large surface area for uptake of water and ions |
Why is the root tip covered by a cap of cells | Protects dividing cells of the top and lubricates root movement |
Meristem in roots | Increase height of plants |
Meristem in stem | Increase plant girth |
Stele | Section in middle of transverse section of dicotyledonous root Endodermis Xylem tissue Phloem tissue |
Water uptake | Water enters capillaries from soil (osmosis) Apoplast and symplast pathways (root hair cells to cortex) Water leaves apoplast at endodermis and enter from symplast Water enters xylem under root pressure then travels in tracheids and vessel elements Water carried to mesophyll through small veins Evaporates in leaf air spaces and from stomata |
Pith | Made of parenchyma cells | Forms inner cortex |
Epidermis in plants | Protects moist under tissues from desiccation and invasion of pathogens |
Transpiration | Loss of water from a plant | H2O moves from an area of high hydrostatic pressure to areas of low |
What is transpiration affected by | Gravity Electrostatic forces Water potential |
How does water enter the xylem from the soil | H2O moves into cell as active transport transports inorganic ions into the cell (ATP) Lowers H2O potential --> higher conc. of solute; conc. gradient H2O can moves from an area of high WP (soil) to an area of low WP (cell) - osmosis |
Translocation | Movement of dissolved solutes (sucrose) from sources to sinks through the phloem |
Why is translocation bidirectional | Roots can act as a sink by releasing carbs and also as a store depending on time of year |
Process of translocation | Glucose formed in photosynthesis and condensed (sucrose) Moves into companion cell by active transport (active loading) Reduces WP allowing H2O to move in (osmosis) Creates high hydrostatic pressure - mass flow Sucrose diffuses out of phloem to where it's needed for growth and storage |
Mass flow | Assimilates enter sieve tube and lower wp Water enters through osmosis and increases hydrostatic pressure Assimilates leave at sink and increase wp Water leaves and lowers hydrostatic pressure High hydrostatic pressure, forcing sap through vessels towards regions of lower pressure |
How does the process of translocation reoccur | Sink removes sugar, increases WP --> H2O leaves tubes (osmosis) keeping hydrostatic pressure low |
Tonoplast | Membrane around cell wall |
Function of endodermis | Controls amount of H2O coming in (casparian strip) |
What is the Caspian strip made of | Suberin - impermeable to water, lipid |
What does Casparian strip stop | Movement of water through the apoplast |
Source to sink | Sugar moving from where its made to where its stored |
Possible sinks | Seeds Fruit Meristems Roots |
Possible sources | Leaves Food stores in seeds when they geminate Storage organs |
How does water get up the xylem | Root pressure Capillary action Transpirational pull H2O cannot return to cortex through apoplast therefore pressure builds up in cortex pushing H2O up xylem |
Root pressure | Endodermis in roots uses metabolic energy to pump ions into root Reduces WP in xylem and medulla H2O moves across endodermis into medulla (osmosis) |