From the root, water (alongwith dissolved minerals) moves up the plants through xylem tubes to stem and leaves. In some trees water has to reach a height of 100 meters or even more. How does water moves up the plants?
As a matter of fact water is pulled up through the xylem when it is evaporated from the leaves. Water first evaporates from mesophyll cells inside a leaf. Water vapors then diffuses out through tiny holes, called stomata (Singular stoma), into the air.
This loss of water by evaporation from plants is called transpiration.
Remove all the leaves of one plants leaving its stem naked. Keep leaves of the other plants intact. Cover each pot and its soil with polythene bag. It would eliminate effect of evaporation from the pots and the soil. Place the pots on dry glass sheets which have been put on a table in a well lighted part of the room. Take two large sized glass bell-jars and wipe them dry thoroughly from inside as well as outside.
Cover both the pots with bell-jars.
You may use large, transparent polythene bags instead of bell-jars.
After sometime you will see that set up "b" starts appearing misty inside. Touch inner surface of bell-jar "b". It would be wet. These changes would not appear in
set up "a".As a matter of fact water is pulled up through the xylem when it is evaporated from the leaves. Water first evaporates from mesophyll cells inside a leaf. Water vapors then diffuses out through tiny holes, called stomata (Singular stoma), into the air.
This loss of water by evaporation from plants is called transpiration.
Remove all the leaves of one plants leaving its stem naked. Keep leaves of the other plants intact. Cover each pot and its soil with polythene bag. It would eliminate effect of evaporation from the pots and the soil. Place the pots on dry glass sheets which have been put on a table in a well lighted part of the room. Take two large sized glass bell-jars and wipe them dry thoroughly from inside as well as outside.
Cover both the pots with bell-jars.
You may use large, transparent polythene bags instead of bell-jars.
After sometime you will see that set up "b" starts appearing misty inside. Touch inner surface of bell-jar "b". It would be wet. These changes would not appear in
Water surface would indicated evaporation of water (transpiration) from the leaves.
Record your Observation and explain the difference between the two set ups.
As soon as the water evaporates through transpiration more water is conducted from the root through xylem.
Flow of water is fastest on warm, dry sunny days when transpiration is fastest. It slows down on cold and cloudy days when transpiration slows down.
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