Water Relations

Question 1

Name 4 reasons water movement in plants is important

Answer 1

Cooling; long distance of minerals, hormones, and sugars; leaf movement/curling, opening and closing of stomata; growth from elongation

Question 2

What is the general equation for transpiration?

Answer 2

water loss / area * time

Question 3

How does water exit the leaf into the air?

Answer 3

Through the stomata

Question 4

What comes into the cell to replace water thats leaving?

Answer 4

CO2

Question 5

Whats another word for the epidermis?

Answer 5

Dermal tissue

Question 6

What is the ground tissue?

Answer 6

The part of the plant containing the mesophyll cells where photosynthesis takes place, not the epidermis to vascular tissue

Question 7

What are the two types of vascular tissue?

Answer 7

Xylem and Phloem

Question 8

What is the driving force for transpiration?

Answer 8

concentration gradient of water vapor

Question 9

What is the more complicated equation for transpiration?

Answer 9

(concentration of water vapor internal - concentration external) / resistances

Question 10

What are the three resistances to transpiration and which two are the most important?

Answer 10

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

Question 11

What are three types of boundary layer resistance?

Answer 11

Waxy exterior, trichomes, wiggly surface

Question 12

How does transpiration relate to temperature?

Answer 12

Increases until it plateaus
- increased ability for water to vaporize
- plants use it to cool down

Question 13

How does transpiration relate to humidity?

Answer 13

Decreased transpiration with high humidity

Question 14

What are the two factors that influence the concentration gradient (transpiration)?

Answer 14

Humidity and temperature

Question 15

What are the four factors that influence resistance (transpiration)?

Answer 15

Leaf morphology, light, [CO2], wind

Question 16

How does wind influence transpiration?

Answer 16

Increased wind = more transp

Question 17

What’s up with cohesion and adhesion?

Answer 17

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

Question 18

Does water move from high potential to low or vice versa?

Answer 18

Yes, high to low

Question 19

What is the equation for water potential?

Answer 19

Water potential = pressure potential + solute potential

Question 20

Does water move from areas of high pressure to low or vice versa?

Answer 20

Yes, high to low

Question 21

Does water move from areas with high solute concentrations to low or vice versa?

Answer 21

Vice versa

Question 22

Does water with high water potential or water with low water potential want to move more?

Answer 22

High water potential

Question 23

Does water with a bunch of solutes in it want to move?

Answer 23

No the water is busy

Question 24

Is the pressure potential inside a typical plant cell positive or negative? and what does this mean

Answer 24

Positive –> water wants to leave the cell

Question 25

What is turgor pressure?

Answer 25

The force inside the cell that pushes out against the cell wall

Question 26

What is wall pressure?

Answer 26

The force of the strong cell wall pushing back against turgor pressure

Question 27

Which is usually stronger, turgor or wall pressure?

Answer 27

They are equal

Question 28

How does the humidity of air influence the water potential of the air?

Answer 28

Increased humidity increases water potential

Question 29

Whats the difference between xylem and phloem?

Answer 29

Xylem transports aqueous things --> water, soluble nutrients Phloem transports organic things --> sugars, proteins

Question 30

What are the 4 types of xylem vessel things we learned about?

Answer 30

Simple water conducting cells First vascular tissues Tracheids Vessel elements

Question 31

Which types of xylem things provide the most structural support?

Answer 31

Tracheids and vessel elements

Question 32

Which of the xylem things is found in all vascular plants?

Answer 32

Tracheids

Question 33

Where are vessel elements found?

Answer 33

Gnetophytes and angiosperms

Question 34

What substance provides the structure in xylem thingies?

Answer 34

Lignin

Question 35

What is the disadvantage of simple water conducting cells? Where are they found current day?

Answer 35

Water has to move from cell to cell which is very slow, also no structural support. Found in mosses

Question 36

What is auxin?

Answer 36

A growth hormone in plants --> initiates cell elongation

Question 37

What is a palisade cell?

Answer 37

The nicely lined up mesophyll cells in the middle of the leaf