Transpiration and factors affecting the rate

• What do plants require for photosynthesis?

  CO2
• How does CO2 enter the plant?

  Through the stomata
• What happens to guard cells when they are turgid?

  They cause the stomata to open
• What occurs when guard cells lose water?

  They become flaccid and cause the stomata to close
• Where does water evaporate from during transpiration?

  From the surface of the cells in the air spaces of the mesophyll
• What is transpiration?

  The movement of water vapor through the open stomata
• What is the transpiration stream?

  Water is pulled up through the xylem to replace lost water
• What happens to water uptake by the roots during transpiration?

  More H2O is taken up by the roots
• What conditions affect the rate of transpiration?

  Conditions that affect the rate of photosynthesis
• What are two factors that increase the rate of photosynthesis?

  Light intensity and temperature
• How does humidity affect the rate of transpiration?

  Very humid conditions lower the concentration gradient and slow the rate
• What happens in dry conditions regarding transpiration?

  Higher water concentration gradient leads to a faster rate
• How does air movement affect transpiration?

  Lots of air movement maintains a steep concentration gradient, increasing the rate
• What do plants want to achieve regarding water loss and photosynthesis?

  Reduce water loss while still photosynthesizing
• What role does the thick waxy cuticle play in plants?

  It waterproofs the leaf, preventing water loss
• How does the waxy cuticle affect transpiration?

  It reduces the surface area for transpiration
• What is the function of stomata in plants?

  They open and close to regulate water loss
• Under what conditions do stomata typically open?

  In more favorable conditions
• What are the factors affecting the rate of transpiration?

  • Light intensity
  • Temperature
  • Humidity
  • Air movement (wind)
• What are the adaptations plants have to reduce water loss?

  • Thick waxy cuticle
  • Reduced surface area for transpiration
  • Regulation of stomata opening and closing