BY2 - Transport In Plants
- Created by: beth-marie2511
- Created on: 26-03-16 13:26
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- BY2 - Transport In Plants
- Structure & Distribution of Vascular Tissue
- Vascular bundle consists of to main tissues.
- Xylem
- Arranged centrally in the roots.
- Anchors plant into the soil.
- Transports water and minerals.
- Made up of vessels and tracheids.
- Vessels form continuous tubes.
- Their walls are made of lignin.
- Waterproof
- Strenthens plant.
- Prevents the plants from collapsing under suction or tension.
- Mature xylem vessels are dead and have no cytoplasm.
- This is advantageous because there is nothing blocking the flow of water and minerals.
- Their walls are made of lignin.
- Tracheids have tapered ends.
- This is so they can 'fit' together.
- Pits allow the transfer of water between cells.
- Vessels form continuous tubes.
- Arranged centrally in the roots.
- Phloem
- Xylem
- Vascular bundle consists of to main tissues.
- Root Structure
- Epidermis
- Single layer of cells with long extensions called root hairs.
- Hairs provide a large surface area so more water can be absorbed.
- Endodermis
- Singular layer of cells that surround the vascular bundle.
- Cells contain suberin which is waterproof.
- Waterproof layer is the Casparian *****.
- Pericycle
- Contains meristematic cells for growth.
- Vascular Bundle
- Contains xylem and phloem cells.
- Epidermis
- Water & Mineral Transport (roots)
- Water enters the plant via the root hair cells.
- This occurs via osmosis.
- Water moves from a high water potential to a lower water potential.
- This occurs via osmosis.
- Water can cross the root by one of these three pathways:
- Apoplast Pathway
- Water moves through the cell walls.
- Apoplast pathway stops at the endodermis because of the Casparian *****.
- This seals the cell walls (it is waterproof).
- At this point water must cross the cell membranes via osmosis.
- Water then travels via the symplast pathway.
- Some of the uptake of water goes into the xylem.
- Water is now in the cell
- Nucleus has control over the cell content.
- Water is now in the cell
- Some of the uptake of water goes into the xylem.
- Water then travels via the symplast pathway.
- Apoplast pathway stops at the endodermis because of the Casparian *****.
- Water moves through the cell walls.
- Symplast Pathway
- Vacuolar Pathway
- Water moves through the vacuoles of cells.
- Via osmosis
- Water crosses the cell wall cytoplasm of each cell.
- Apoplast Pathway
- Water enters the plant via the root hair cells.
- Movement of Water from Roots to Leaves
- 1. Water moves in by osmosis, either by the apoplast, symplast or vacuolar pathways to the xylem.
- 2. Water moves up the xylem by a 'pulling' effect called the transpiration stream.
- Cohesive forces between molecules and adhesive forces between the water molecules and the xylem.
- 3. Water evaporates through the stomata so that more water molecules are pulled up to replace those that have been lost.
- 4. High hydrostatic pressure and high root pressure is caused by water entering the roots.
- 5. Lower hydrostatic pressure as water is being lost.
- 6. Capillarity - Water rising up narrow tubes.
- 5. Lower hydrostatic pressure as water is being lost.
- 4. High hydrostatic pressure and high root pressure is caused by water entering the roots.
- 2. Water moves up the xylem by a 'pulling' effect called the transpiration stream.
- The main force that pulls water up is transpiration.
- Water travels in the xylem, up through the stem and to the leaves where most of it evaporates as water vapour into the atmosphere.
- This creates a 'pull' - more water is puled up the stem.
- Cohesion
- Strong attraction water molecules exert on one another.
- This attraction pulls up other water molecules.
- Adhesive Forces
- Attraction or adhesion between the water molecules and the xylem wall, which is hydrophilic.
- Cohesive and adhesive forces combine - COHESION-TENSION THEORY.
- Capillarity
- Another force that contributes to the water moving up narrow tubes.
- Root Pressure
- (High hydrostatic pressure) A build up a high water potential in the roots compared to the low water potential in the leaves.
- Water travels in the xylem, up through the stem and to the leaves where most of it evaporates as water vapour into the atmosphere.
- 1. Water moves in by osmosis, either by the apoplast, symplast or vacuolar pathways to the xylem.
- Structure & Distribution of Vascular Tissue
- Vascular bundle is arranged on the periphery of the stem.
- Gives the flexible support to the plant and resistance to bending.
- Vascular bundle consists of to main tissues.
- Xylem
- Arranged centrally in the roots.
- Anchors plant into the soil.
- Transports water and minerals.
- Made up of vessels and tracheids.
- Vessels form continuous tubes.
- Their walls are made of lignin.
- Waterproof
- Strenthens plant.
- Prevents the plants from collapsing under suction or tension.
- Mature xylem vessels are dead and have no cytoplasm.
- This is advantageous because there is nothing blocking the flow of water and minerals.
- Their walls are made of lignin.
- Tracheids have tapered ends.
- This is so they can 'fit' together.
- Pits allow the transfer of water between cells.
- Vessels form continuous tubes.
- Arranged centrally in the roots.
- Phloem
- Xylem
- Vascular bundle is in the midrib of the leaves.
- Gives flexibility and strength.
- Cortex
- Thick layer of packing cells (parenchyma)
- Root Structure
- Epidermis
- Single layer of cells with long extensions called root hairs.
- Hairs provide a large surface area so more water can be absorbed.
- Endodermis
- Singular layer of cells that surround the vascular bundle.
- Cells contain suberin which is waterproof.
- Waterproof layer is the Casparian *****.
- Pericycle
- Contains meristematic cells for growth.
- Vascular Bundle
- Contains xylem and phloem cells.
- Epidermis
- Water travels through the cytoplasm.
- Via osmosis
- Down a water potential gradient.
- Via the plasmaodesmata.
- Down a water potential gradient.
- Symplast Pathway
- Via osmosis
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