Transport in plants

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What does the xylem carry around the plant?
Water and mineral salts
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What does the phloem carry around plant?
Mainly sugars
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What is the driving force of the water moving up the xylem?
Evaporation due to transpiration (as a concentration gradient is created)
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Give an advantage of root hair cells?
Increases surface area to absorb more water and minerals
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What substance makes the xylem strong?
Lignin
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Describe the structure of xylem
long, tubular, formed by fusion end to end, the cells are hollow and dead, strengthed by lignin
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How does water enter the root hair cells?
Osmosis
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How are mineral ions taken in by the root hair cells?
Active transport
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Describe the route taken by water to reach the xylem via the symplastic pathway
Water enters the root hair cell by osmosis, water diffuses across across the cell due to the concentration gradient into the epidermis, water diffuses across and through the plasmodesmata into the cortex then into the endothermis then into the xylem
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Describe the root taken by water to reach the xylem via the apoplastic pathway
Water diffuses across the cells in the cell wall until it's stopped by the casperian ***** and forced into the endothermis and enters the xylem
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Which 3 factors cause water to move up towards the xylem?
Root pressure, Co-hesion tension theory and capillary action
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What is root pressure?
The mineral ions are actively transported into xylem vessels in the root by endodermal cells. This makes the water potential of the xylem more negative and causes water to enter the xylem by osmosis
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What is capillary action?
is responsible for some water creeping up the xylem vessels simply because they are very narrow
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Explain the cohesion tension theory
Water evaporating from the leaves drives the movement of water from the roots. The evaporation creates a WP gradient & the properties of water which allows them to cohere pulling up more water molecule behind them, driving water up the xylem
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Explain why a tree trunk is smaller at midday than at night
The transpiration rate is at it's highest forcing more water upward, due to the cohesion tension theory, the xylem is 'sucked' inwards shrinking the diameter of the trunk
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Other cards in this set

Card 2

Front

What does the phloem carry around plant?

Back

Mainly sugars

Card 3

Front

What is the driving force of the water moving up the xylem?

Back

Preview of the front of card 3

Card 4

Front

Give an advantage of root hair cells?

Back

Preview of the front of card 4

Card 5

Front

What substance makes the xylem strong?

Back

Preview of the front of card 5
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