transport in plants
DESCRIPTION
For IGCSE O-Level Biology students Chapter 8TRANSCRIPT
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Transport in plants
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Transport systems
There are two transport systems in a plant.
One that transports water and minerals from root to all other parts. These vessels are called ………….
Another vessels transport sugars (sucrose) and amino acids made in leaves to all other plant parts. These are called phloem vessels.
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Xylem vessels
Are long , hollow, continuous tubes that carry water and dissolved minerals from the root up to all parts of the plant.
Contain a tough substance called lignin that lines the walls to provide support.
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Phloem vessels
Phloem tubes are living cells with end tubes with pores (sieve plate).
All cell contents have disappeared except the cytoplasm
The phloem cells have companion cells near them.
Phloem cells transport sucrose and amino acids from where they are made to where they are used or stored.
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Dicot stem Dicot root
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Stem structure
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Root structure
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How water moves into the plant.
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Transpiration
It is the loss of water vapour out of leaves (and stems) through stomata by diffusion.
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Experiments
1. measure water uptake by plant shoots.
2. Show that transpiration takes place in shoots.
3. Show there are more stomata on the lower side of a leaf.
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Potometer
A potometer measures the rate of water uptake.
The distance moved by the air bubble can be measured every minute to show the rate of water uptake.
The air bubble can be moved back to the start position by…………………….
Water is not only lost by transpiration in the leaves it is also used by the leaves during ………….….
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Put your thinking caps on!
Predict what would happen to the rate of water uptake if the temperature increases.
When the wind speed increases?When light intensity increases?When humidity increases?
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Transpiration is affected by
Weather condition Rate of transpiration Why?
Windy Speeds up transpiration
Moist air around the
leaf is blown away
Humid Slows down transpiration
Air around the leaf is
already full of
moisture
Warm Speeds up transpiration
Evaporation occurs faster
Light Speeds up transpiration The stomata opens
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Translocation
Is moving food (sucrose and amino acids) from the sources (leaf, root) to sinks (developing flowers/fruits, storage organs) through the phloem vessels.