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929 Explain how the abiotic factors

Page history last edited by Jay 14 years, 3 months ago

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Effect of abiotic factors in the rate of transpiration.

 

  • Transpiration is a process where water is lost as vapor from leaves and other aerial parts of the plant. The water is lost through the opening of the stomata. Furthermore the opening and closing of the stomata regulates the rate of transpiration in a plant. 
  • Water that is lost by transpiration is replaced by water absorption. More than 90% of the water taken in by the roots is lost by transpiration, showing how only 10% of the water are actually used by the plant for photosynthesis.
  • Even though water is lost by transpiration can affect not only the growth but also the productivity of the plant, it is a fundamental process in plants survival because through transpiration, the sun-drenched leaves and stems are cooled. Furthermore an analogy of human sweat and plant transpiration can be made. Where both water losses function as cooling. 
  • However, it is crucial to balance the rate of transpiration and water absorption of the plant. Because if there were to be more transpiration than water absorption by the plant roots, then there would be a water deficiency that can lead to the death of a plant.  

 

<http://techalive.mtu.edu/meec/module01/images/transpiration.jpg>

 

http://www.apm-realty.com/7as-artesian/images/Transpiration.jpg

Light

  • Light speeds up transpiration by warming the leaf and opening stomata. The warming of the leaf leads to transpiration because water is needed to cool the leaf so that it doesn't dry out.
  • In addition, light triggers the activity of ATP-powered proton pumps in the plasma membrance of guard cells. This triggers the active transport of potassium into the cell. The higher solute concentration within the guard cells causes inward water movement due to osmosis.
  • When potassium ions passively leaves the cells, water also leaves. 



Humidity 

  • Decreasing humidity increases transpiration because of the greater difference in water concentration. In contrast increasing humidity decreases transpiration because the main purpose of transpiration is to keep the leaves humid.
  • High humidity means a higher water potential in the air, so a lower water potential gradient between the leaf and the air, so less evaporation.  



Temperature

  • High temperature increases the rate of evaporation of water from the spongy cells, and reduces air humidity, so transpiration increases.

 

 

Environmental Factor

Effects

Light

Speeds up transpiration by warming the leaf and opening stomata (the warming of the leaf leads to transpiration because water is needed to cool the leaf so that it doesn't dry out)

Humidity

Decreasing humidity increases transpiration because of the greater difference in water concentration. In contrast increasing humidity decreases transpiration because the main purpose of transpiration is to keep the leaves humid.

Wind

Increases the rate of transpiration because humid air near the stomata is carried away

Temperature

Increases temperature causes greater transpiration because more water evaporates

Soil water

If the intake of water at the roots does not keep up with transpiration, turgor loss occurs and the stomata close-this decreases transpiration

Carbon Dioxide

High carbon dioxide levels in the air around the plant usually cause the guard cells to lose turgor and the stomata to close

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OBJL1-List 4 abiotic factors that affect the rate of transpiration in a plant.(4) 

OBJL2-Describe the role of transpiration in a plant.(3)

OBJL3-Compare and contrast the effect light has on Transpiration and the effect temperature has on Transpiration. (5) 

 

Comments (3)

Jay said

at 10:04 pm on Apr 22, 2010

You guys are both goofy! :)

HL-Jin Su said

at 6:53 pm on Apr 20, 2010

wow akira...thnx...

HL-Akira said

at 12:40 pm on Apr 19, 2010

This is actually a helpful source of information, thanks for photos it extended my understanding.

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