Water Relations Flashcards
Name 4 reasons water movement in plants is important
Cooling; long distance of minerals, hormones, and sugars; leaf movement/curling, opening and closing of stomata; growth from elongation
What is the general equation for transpiration?
water loss / area * time
How does water exit the leaf into the air?
Through the stomata
What comes into the cell to replace water thats leaving?
CO2
Whats another word for the epidermis?
Dermal tissue
What is the ground tissue?
The part of the plant containing the mesophyll cells where photosynthesis takes place, not the epidermis to vascular tissue
What are the two types of vascular tissue?
Xylem and Phloem
What is the driving force for transpiration?
concentration gradient of water vapor
What is the more complicated equation for transpiration?
(concentration of water vapor internal - concentration external) / resistances
What are the three resistances to transpiration and which two are the most important?
S: stomatal resistance (small size, small apertures, low density)
B: boundary layer (waxy exterior, trichomes, wiggly surface)
I: internal resistance (packed interior / increased internal density) not as importane
What are three types of boundary layer resistance?
Waxy exterior, trichomes, wiggly surface
How does transpiration relate to temperature?
Increases until it plateaus
- increased ability for water to vaporize
- plants use it to cool down
How does transpiration relate to humidity?
Decreased transpiration with high humidity
What are the two factors that influence the concentration gradient (transpiration)?
Humidity and temperature
What are the four factors that influence resistance (transpiration)?
Leaf morphology, light, [CO2], wind
How does wind influence transpiration?
Increased wind = more transp
What’s up with cohesion and adhesion?
Water is attracted to itself and the walls of vascular system –> is pulled up by transpiration, which pulls water out of the soil and into the roots
Does water move from high potential to low or vice versa?
Yes, high to low
What is the equation for water potential?
Water potential = pressure potential + solute potential
Does water move from areas of high pressure to low or vice versa?
Yes, high to low
Does water move from areas with high solute concentrations to low or vice versa?
Vice versa
Does water with high water potential or water with low water potential want to move more?
High water potential
Does water with a bunch of solutes in it want to move?
No the water is busy
Is the pressure potential inside a typical plant cell positive or negative? and what does this mean
Positive –> water wants to leave the cell
What is turgor pressure?
The force inside the cell that pushes out against the cell wall
What is wall pressure?
The force of the strong cell wall pushing back against turgor pressure
Which is usually stronger, turgor or wall pressure?
They are equal
How does the humidity of air influence the water potential of the air?
Increased humidity increases water potential
Whats the difference between xylem and phloem?
Xylem transports aqueous things –> water, soluble nutrients
Phloem transports organic things –> sugars, proteins
What are the 4 types of xylem vessel things we learned about?
Simple water conducting cells
First vascular tissues
Tracheids
Vessel elements
Which types of xylem things provide the most structural support?
Tracheids and vessel elements
Which of the xylem things is found in all vascular plants?
Tracheids
Where are vessel elements found?
Gnetophytes and angiosperms
What substance provides the structure in xylem thingies?
Lignin
What is the disadvantage of simple water conducting cells? Where are they found current day?
Water has to move from cell to cell which is very slow, also no structural support. Found in mosses
What is auxin?
A growth hormone in plants
–> initiates cell elongation
What is a palisade cell?
The nicely lined up mesophyll cells in the middle of the leaf
