Plant Transport

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Why do plants need a transport system?
1) metabolic demands (parts of plants that dont photosynthesis and need glucose , hormones) 2) Size (continuously growing, needs an effective transport system to move stuff all over) 3) SA:V (Some parts large, small in others, cant rely on diffusion)
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What is the vascular bundle?
An organ in the plant made up of transport tissues (Xylem and Phloem)
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What is the role of the VB?
To transport substances and to give the plant support
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Name the different places the VB is found in different areas of the plant
Roots- Around the edge, Stem- In the middle, Leaves- Spread out as veins
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Describe the structure and function of the Xylem
Transports water and mineral ions, xylem vessels (elongated hollow cells), xylem parenchyma (stores food and contains tannin) Tannin (bitter substance to protect plant from herbivores) Lignified secondary wall (support and strength)
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Describe the structure and function of the phloem
transports organic solutes up and down the plant, sieve tube elements (long hollow cells with broken down nucleus and organelles, filled with phloem sap, not lignified), Sieve plates (perforated wall in between sieve tube elements) Companion cells
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What is the role of the companion cell?
The companion cell is like the life support for the STE because they have broken down organelles ect, Plasmodesmata are microscopic pores that link the CC with the STE, this allows the CC to carry out normal cell functions for itself and the STE
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Name 5 points as to how water helps plants in terms of structure and metabolism
1) turgor pressure, hydrostatic skeleton, support. 2) Turgor also drives cell expansion, roots can penetrate tarmac ect 3) Evaporation to keep plants cool 4)Transport 5) Needed for photosynthesis
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How are root hair cells adapted as exchange surfaces?
Microscopic size (can penetrate easily), hair projections give it a large SA:V, thin surface layer (short diffusion pathway), high conc of solutes in cytoplasm maintains WP gradient
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Describe the symplast pathway
Water travels through the symplast (continuous cytoplasm connected through plasmodesmata), the root hair cell has a higher WP than the next cell so the water keeps moving along to the next cell until reaching the xylem
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Describe the apoplast pathway
Water travels through the apoplast (cell walls and intracellular spaces) as water moves into the xylem, more water is pulled into the plant due to cohesive forces, this creates a tension meaning there is a continuous flow
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What is the tonoplast pathway?
Where water travels through the cell wall membrane and the vacuoles, very slow.
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Explain the movement of water into the xylem
The water in the apoplast pathway reaches a waterproof waxy layer called the Casparian strip around the endodermal cells, this forces the water into the cytoplasm of the EC to join the symplast pathway. WP of xylem cells is lower than EC, goes in Xm
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What is an advantage of the water on the apoplast pathway being moved onto the symplast pathway?
It has to go through the selectively permeable membrane which filters out any potentially toxic substances to the plant
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What is root pressure?
Pressure caused by the active pumping of minerals into the xylem to produce movement of water by osmosis. Root pressure gives water a push up the xylem.
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Card 2

Front

What is the vascular bundle?

Back

An organ in the plant made up of transport tissues (Xylem and Phloem)

Card 3

Front

What is the role of the VB?

Back

Preview of the front of card 3

Card 4

Front

Name the different places the VB is found in different areas of the plant

Back

Preview of the front of card 4

Card 5

Front

Describe the structure and function of the Xylem

Back

Preview of the front of card 5
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