2.3B Water transport

Question 1

what is transpiration

Answer 1

evaporation from leaves

Question 2

what are the 3 section of water movement

Answer 2

1. movement through roots
2. movement through stem
3. movement through leaf

Question 3

what are the 2 paths that water moves through roots

Answer 3

1. sympath pathway
2. apoplast pathway

Question 4

is apoplast or aeoplast faster

Answer 4

apoplast

Question 5

what is the symplast pathway

Answer 5

• moves through the cytoplasm of one cell, to the cytoplasm of an adjacent cell (via plasmodesmata)
• moves across cortex via osmosis (down water potential gradient)

Question 6

how does water move into root hair cells

Answer 6

via osmosis from soil

Question 7

what is the apoplast pathway

Answer 7

• water moves within cell walls + spaces between cells
• quicker, water moves easily through cellulose fibres + less resistance to water flow

Question 8

what is cohesion

Answer 8

when water molecules are attracted to eachother

(due to hydrogen bonds)

Question 9

how is the apoplast pathway driven

Answer 9

by cohesion

Question 10

how is the symplast pathway driven

Answer 10

by water potential gradient(between root hair cells and xylem)

Question 11

what must happen before water can pass into the xylem (apoplast)

Answer 11

pass through a layer of cells: endodermis

Question 12

what in the endodermis causes the apoplast pathway to stop

Answer 12

casparian strip

Question 13

what is the casparian strip made of

Answer 13

Suberin (waterproof)

Question 14

what does the casparian stip do?

Answer 14

disallow water to move via the apoplast pathway

Question 15

how does water move after it has encountered the casparian strip

Answer 15

moves through cell membrane, into cytoplasm (becoming part of the symplast pathway)
This allows the cell membrane to choose what can enter the xylem

Question 16

how is the water potential in the xylem lowered?

Answer 16

cells in endodermis pump ions into xylem (via active transport)

Question 17

why is water potential lowered in the xylem

Answer 17

triggering water to move into xylem via osmosis. this is called ROOT PRESSURE

Question 18

what does ROOT PRESSURE require

Answer 18

ATP

Question 19

what happens to ROOT PRESSURE if a respiratory inhibitor is used

Answer 19

it stops. No ATP is being produced

Question 20

what happens to ROOT PRESSURE if oxygen is excluded

Answer 20

stops. no ATP