1. February 7 2013 Focus Question: How does a plant maintain homeostasis?

2. Plant Homeostasis

3. Homeostasis: balance of a system
Turgid: full of water (crisp)
Flaccid: not full of water
Wilt: plants wilt when they are not full of water

4. Transpiration: loss of water by a plant
Water is taken up through the roots and leaves via the stoma on the leaves

5. Stoma (stomata) are the pores on the underside of the leaf
Opening and closing of the stoma are regulated by the guard cells

6. When the guard cells are turgid they pull apart from each other, opening the stoma and allowing gas and water to leave

7. When the guard cells are flaccid they seal the stoma shut, preventing water loss

8. When the stoma are open the plant can undergo photosynthesis
When the stoma are closed, no photosynthesis can take place because no gas exchange

9. When stoma are open…
Gas exchange
Photosynthesis
Water loss

10. When stomata are closed…
No glucose production
No gas exchange
No water loss

11. Virtual Lab

12. Factors that affect transpiration rate
Light
In bright light transpiration
The stomata open wider to allow for gas exchange during photosynthesis
Increases

13. Factors that affect transpiration rate
Temperature
Transpiration is faster at high temperatures OR
Transpiration is slower at low temperatures
Evaporation and diffusion are faster at higher temperatures

14. Factors that affect transpiration rate
Wind
Transpiration is faster in windy conditions
Water vapor is removed quickly by air movement, speeding up diffusion of more water vapor

15. Factors that affect transpiration rate
Humidity
Transpiration is slower in humid conditions
Diffusion of water out of leaf slows down if leaf is already surrounded by water vapor