Transport of Water & Transpiration.

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  • Created by: ElishaG
  • Created on: 05-04-17 20:12
What does endodermis do?
Actively transports ions to xylem to maintain concentration- increases hydrostatic pressure.
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What are the 3 pathways water can travel through to move into the xylem?
1)Apoplast Pathway.2)Symplast Pathway.3)Vacuolar Pathway.
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Where does water travel when it moves via the apoplast pathway?
Through fully permeable cell wall- toxins are not removed so the Casparian ***** helps/
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Where does water travel when it moves via the symplast pathway?
Only travels through cytoplasm- filtered by membranes that remove toxins.
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Where does water travel when it moves via the vacuolar pathway?
Cytoplasm and vacuole- filtered by membranes so toxins removed.
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LEARN DIAGRAM FOR THIS..
..
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How is the Casparian ***** formed?
1)Endodermis cells secrete waxy substance (suberin).2)Waterproofed cell walls form Casparian *****.
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What happens to water from the apoplast pathway when it reaches the Casparian *****?
1)Blocked by endodermis.2)Forced to cross partially permeable plasma membrane.
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What is Transpiration?
Evaporation and diffusion of water vapour from the leaf into the atmosphere via the stomata.
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Why does transpiration have to occur?
Because the plant cannot close the stomata to prevent it as carbon dioxide enters the plant via the stomata for photosynthesis.
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How do water molecules move up the xylem?
By mass flow.
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What is mass flow?
The movement of a body of water from an area of high pressure to an area of lower pressure.
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What is cohesion?
Hydrogen bonding between water molecules.
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What is adhesion?
Hydrogen bonding between water and xylem vessel walls.
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What does adhesion prevent?
Water falling down the plant.
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What are the 10 labels for a leaf cross-section? LEARN TO LABEL.
1)Waxy cuticle.2)Upper epidermis.3)Lower epidermis.4)Pallisade mesophyll.5)Spongy mesophyll.6)Guard cells.7)Stomata.8)Xylem.9)Phloem.10)Air space.
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Explain what happens when water in the xylem reaches the leaves.
1)Water leaves xylem by osmosis.2)Water moves to spongy mesophyll cells via apoplast and symplast pathways.3)Water evaporates into air spaces.4)Water vapour diffuses through stomata into outside air.
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What drives the mass flow of water up the stem from the roots?
Low pressure in the leaf.
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What can be used to measure the rate of transpiration?
A potometer.
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What does a potometer estimate?
The rate of water loss.
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There are 7 pieces of equipment needed for a potometer, what are they?
1)Stopwatch.2)Ruler-measure distance meniscus travelled.3)Water in beaker.4)Capillary tube-air bubbles move through it using cohesion and adhesion.5)Vaseline-sealant.6)Reservoir-reset experiment.7)Healthy shoot-effective measure,xylem intact.
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What is done to prevent air bubbles in the xylem?
Shoot is cut underwater.
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What are xerophytes?
Plants that are well adapted to living in very dry conditions with little rainfall, e.g. cacti.
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Name and explain 5 adaptations of xerophytes.
1)Smaller leaves-reduces SA, spines protect.2)Stems for photosynthesis-thick,fleshy tissue.3)Waxy cuticle-reduce water loss.4)Hairs on leaves-prevent transpiration via stomata.5)Sunken stomata-reduces evaporation rate,longer diffusion path.
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What are hydrophytes?
Plants that grow in water- partially or completely.
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Name and explain 6 adaptions of hydrophytes.
1)No waxy cuticle-water loss not a problem.2)Stomata on upper surface-cuticle repels water to keep stomata open.3)Large SA of stems-anchorage.4)Air sacs-flotation.5)Reduced structure-not much strengthening tissue,more flexible.6)Wide leaves-more SA
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Other cards in this set

Card 2

Front

What are the 3 pathways water can travel through to move into the xylem?

Back

1)Apoplast Pathway.2)Symplast Pathway.3)Vacuolar Pathway.

Card 3

Front

Where does water travel when it moves via the apoplast pathway?

Back

Preview of the front of card 3

Card 4

Front

Where does water travel when it moves via the symplast pathway?

Back

Preview of the front of card 4

Card 5

Front

Where does water travel when it moves via the vacuolar pathway?

Back

Preview of the front of card 5
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