Mass transport in plants- transpiration

Question 1

name the properties of water and what effect they have on the xylem

Answer 1

• polar
• cohesive
• engages in hydrogen bonding
  (enables xylem to have a continuous column of water)

Question 2

define transpiration

Answer 2

water evaporating from the leaves via open stomata

Question 3

define transpiration stream

Answer 3

mass flow of water up a plant (down water potential gradient)

Question 4

in plants where is the highest water potential found

Answer 4

roots/soil

Question 5

regarding plants where is the lowest water potential found

Answer 5

the air

Question 6

describe the features of the xylem as a tissue that transports water in the stem and leaves of plants

Answer 6

• facilitates transpiration stream
• dead, hollow, open ended vessel elements
• narrow
• lignified, structurally strong

Question 7

explain how xylem facilitates transpiration stream

Answer 7

provides a one way mass flow of water from roots to leaves to the air, down the water potential gradient

Question 8

reason for dead, hollow, open ended vessel elements in xylem

Answer 8

allows for continuous flow of water

Question 9

reason for narrow xylem

Answer 9

to aid capillary action

Question 10

reason for lignified, structurally strong xylem

Answer 10

to resist the high negative pressure created in the leaf by transpiration (evaporation)

Question 11

Name the uses of water (in the xylem)

Answer 11

• used as a metabolite in photosynthesis
• maintains cell turgidity
• inorganic ions in soil can be transported to leaves