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Bell Ringer - 5 Min
• Why do you need transportation in living organisms? Explain your answer with a suitable example.
Water movement through plants
• How does water move through a plant? – Which part of the plant does water enter?
– Which part of the plant does water leave?
• What do you know already? – With the person next to you discuss for 1 minute
what you already know about the movement of water through plants
Transpiration and Transpiration Pull
• Transpiration is the movement of water molecules through the plant. Up from the roots, through Xylem vessels and evaporating out through the stomata in the leaves.
• During transpiration, water is continually removed from the top of xylem vessels to supply cells in the leaves so pressure at the top of xylem reduces and water flows up.
Evaporation and transpiration
• Evaporation is the process of a liquid turning to gas.
• Transpiration is the release of water vapour from a plant through the leaves, causing water to move through the plant.
Xylem
• The xylem carries water and minerals from the roots to the leaves
• The cellulose cell walls contain extra layers of a chemical called lignin.
• Once xylem cells have formed the xylem they die making long thin vessels for water to move through
Phloem
• The phloem carries dissolved food such as sugars from the leaves to other areas of the plant
• Phloem cells are alive. If they are damaged they cannot work properly.
Xylem & Phloem Xylem Tissue
• made of Tracheid
cells
•transports water from
root to leaves via -
a. Capillary Action
b. Transpiration Pull
Phloem Tissue
• Made of sieve tubes and companion cells
• Transports food (organic molecules) from leaf
to root or vice versa
•sugar transport
Guard Cells & Stomata
• Allow movement of CO2, H2O & O2 into or out of plant
• Transpiration – movement of water out of leaves (through stoma)
• Guard Cell Regulation
Transpiration
• When it is sunny the plant will photosynthesise more meaning stomata are open to allow more carbon dioxide in, more water can be lost.
Transpiration • As humidity
increases the rate of transpiration decreases.
• The higher the humidity the more water there is in the air.
• How do you think this affects the rate of diffusion?
Wilting • If a plant is losing
more water than it can replace, it will begin to wilt.
• This will reduce the amount of water lost as the surface area is reduced.
1. What is the scientific name for water moving through a plant?
2. What is the name of the vein in plants that water moves through?
3. Give 3 ways that affect the rate of transpiration and explain why.
4. What is a potometer?
5. How does wilting reduce water loss?
1. What is the scientific name for water moving through a plant?
Transpiration
2. What is the name of the vein in plants that water moves through?
Xylem
3. Give 3 ways in which water is useful in plants
Cools it down when it evaporates, used for photosynthesis, support, carries dissolved minerals
4. How do plants use osmosis to help them regulate water loss?
Water osmoses into or out of the guard cells to open or close stomata. If guard cells are turgid, stomata is open.
5. Give 2 ways in which plants reduce water loss from them
Few stomata, small leaves, stomata on the bottom of leaf, ability to close stomata (waxy cuticle), wilting
6. Why do water particles move out of the air spaces in leaves into the air?
Because there is a higher concentration of water particles in the air space than outside the leaf so the water particles diffuse out of the leaf
Transport of Organic Nutrients
translocation is the process of transporting
the manufactured carbohydrates in
photosynthesis via phloem from the leaves
to other parts of the plant