Lecture 29- Transport in Vascular Plants

Question 1

how does water climb a tall tree? (3)

Answer 1

capillary action (thinner tube = greater height)
transpiration (occurs where leaves are, allows for water loss)
root pressure (water enters via osmosis)

Question 2

what does the transpirational pull do?

Answer 2

evaporation of water from a plants surface, the water gets replaced as it evaporates

Question 3

what happens to the air as the water evaporates?

Answer 3

it goes further into the mesophyll walls

Question 4

surface tension of water creates a negative pressure potential in the tree, what does that mean?

Answer 4

it pulls water and minerals from the root up with its negative water potential gradient

Question 5

what are the 3 different routes used for water and solute transport?

Answer 5

apoplastic route
symplastic route
transmembrane route

Question 6

where does the apoplastic route go through?

Answer 6

cell wall

Question 7

where does the symplastic route go through?

Answer 7

cytosol (inside cell, and goes between cells through the plasmodesmata)

Question 8

where does the transmembrane route go?

Answer 8

across the cell wall and plasma membrane

Question 9

what is the water potential in plants as they go up the tree?

Answer 9

the highest water potential is close to 0
goes to lower (more -) water potential as it goes up the tree

Question 10

what happens if a dehydrated (flaccid) cell is placed in a solution with lower solute concentration?

Answer 10

cell will gain water and become turgid (firm)

Question 11

what do guard cells look like when turgid?

Answer 11

cells bow outward
pore between them opens

Question 12

what do guard cells look like when flaccid?

Answer 12

less bowed
pore closes

Question 13

what is the main function of bulk flow?

Answer 13

efficient long distance transport of fluid

Question 14

where does most mineral and water absorption occur?

Answer 14

near root tips (because thats where the epidermis is permeable to water)

Question 15

how can water and solutes move through tracheids and vessel elements of the xylem and sieve tube elements of the phloem?

Answer 15

mature tracheids and vessel elements have no cytoplasm
sieve tube elements have few organelles

Question 16

what does the endodermis do?

Answer 16

surrounds the vascular cylinder and is the last checkpoint for selective passage of minerals that can go into the xylem
it also contains a casparian strip

Question 17

what does the casparian strip do?

Answer 17

made of suberin, helps to block apoplastic transfer

Question 18

where are sugars made? (sugar sources)

Answer 18

mesophyll because thats where theres the most amount of chloroplasts

Question 19

where do sugars get transported to via sieve tube elements?

Answer 19

sugar sinks

Question 20

do sugar sinks photosynthesize?

Answer 20

no

Question 21

how can a storage organ be both a sugar source and sugar sink?

Answer 21

depends on the season. can be a sugar source in winter and a sugar sink in summer

Question 22

what route does sugar take through the cells?

Answer 22

symplastic or
both symplastic and apoplastic