Transpiration

Transpiration is a Consequence of Gas Exchange

Four Main Factors Affect Transpiration Rate

 

A Potometer can be Used to Estimate Transpiration Rate

 

Xerophytic Plants are Adapted to Reduce Water Loss

 

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  • Created by: Benedicta
  • Created on: 07-01-11 14:12
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Transpiration
Xerophytic Plants are Adapted to Reduce Water Loss
Like cacti, pine tree and prickly pears adapted to live in dry climates
1. Stomata that are sunk in pits - so they're sheltered from the wind, helps slow transpiration
down
2. Layer of hairs in epidermis - traps moist air round stomata - reduces water potential gradient
between leaf and air, slowing transpiration down
3. Curled leaves - traps moist air, slowing transpiration - lowers exposed surface are for losing
water and protects stomata from wind
4. Spines instead of leaves - reduces surface area for water loss
5. Thick, waxy layer on epidermis - reduces water loss by evaporation because layer waterproof
(water can't move through it)
6. Reduced number of stomata - means fewer places where water can be lost
01 January 2011
20:25
Transpiration is a Consequence of Gas Exchange
Transpiration is the evaporation of water from a plant's surface
1. Plant needs to open its stomata to let in carbon dioxide so that it can produce glucose
(photosynthesis)
2. But this also lets water out - high concentration of water inside leaf than in air outside
3. Water moves out of leaf down water potential gradient when stomata open
4. Transpiration's really a side effect of gas exchange needed for photosynthesis
Four Main Factors Affect Transpiration Rate
1. Light - lighter it is faster the transpiration rate.
Because stomata open when it gets light
When dark, stomata usually closed, so little transpiration
2. Temperature - higher the temperature, faster the transpiration rate
Warmer water molecules have more energy so they evaporate from cells in leaf faster
Increases water potential gradient between inside and outside leaf, making water diffuse out
of leaf faster

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Humidity - lower the humidity, faster transpiration rate.
If air around plant is dry, water potential gradient between leaf and air increased
4. Wind - windier it is, faster transpiration rate.
Lots of air movement blows away water molecules from around stomata.…read more

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