EPS Chapter 4 - Plant Physiology Flashcards
Plant Transport
What is transpiration?
Movement of water and mineral nutrients from the soil to the atmosphere
What is evapotranspiration?
Landscape-level movement of water from soil to atmosphere
Water will evaporate from leaf cells at what RH (relative humidity)?
<100 % RH
How much does water does a corn plant lose per day?
0.5 gallons
How much does water does a large maple tree lose per day?
52 gallons
Transpiration is controlled by?
Guard cells of stomata
Turgid guard cells do what?
Open up stoma (Gk mouth)
When are stomas open?
During the day and closed at the night to prevent unnecessary water loss
Why would stomas be open during the day?
Stomas need LIGHT and CO2 for photosynthesis, which happens in the day
Why can’t plants close their stomata for long periods of time to prevent water loss?
They need stomata to open and bring in CO2 for photosynthesis
Xerophytes have what kind of photosynthesis?
CAM photosynthesis
Xerophytes (CAM plants) have their stomates close when?
Close stomates during the day
Why do Xerophytes (CAM Plants) have a close stoma during the day?
They live in extremely dry climates
Explain how guard cells open
Within the guard cells, there are cellulose microfibrils that run horizontally through the cells.
- Grow in length. NOT by width when filled with water / when there is turgor pressure
- NO water = collapsed
In red is the cellulose microfibrils
What triggers the stomates to open?
Day: K+ ions are transported to guard cells followed by a rush of H20 to increase the turgor pressure of the guard cells = opening up the stomates
K+ ions enter –> water enter –> opening the cell
What triggers the stomates to close?
Night: K+ ions leave the guard cells and water follows = closing the stomates
K+ ion leave –> water leaves –> closing the cell
Why is potassium (K+) needed for stomata opening/closing
K+ in osmosis causes and increases turgor pressure –> causes guard cells to open
When guard cells are flaccid = stomata are ___
Closed
When guard cells are turgid = stomata are ___
Open
What are the lead adaptations to growing in arid environments (desert condition?) (Function?)
Thick cuticle, long dermis, hairs, and sunken stomates for water conservation
How does water move up the plant?
Moves up by going cell wall to cell wall, not through each cell
The xylem doesn’t regulate what enters it. Why?
It is dead when functional
Explain transpiration - cohesion theory
Water has cohesive (water-water) and adhesive (water-cell wall) properties
