chapter 9 - transport in plants

Question 1

phloem structure and function

Answer 1

• living tissue
• non-lignified
• transports food up or down the plant
• sieve tube elements and companion cells

Question 2

xylem structure and function

Answer 2

• non-living tissue
• lignified
• transport of water and mineral ions
• moves up frin roots to shoots & leaves
• long, holliw structures

Question 3

reasons for transport systems

Answer 3

• metabolic demand, make thier own glucose & oxygen by photosynthesis.
• size, big plants need very effective transport.
• SA:V ratio, leaves have large sa:v ratio for the exchange of gases with the air.

Question 4

what is a dicotyledonous plant

Answer 4

• a plant which makes seeds that contain two cotyledons (organs that act as food stores), forms the first two leaves when the seed germinates.

Question 5

where is water taken up

Answer 5

through root hair cells

• long and narrow = increases SA:V
• able to penetrate between soil particles
• able to maintain a water potential gradient between soil and cells

Question 6

how does water move towards the xylem

Answer 6

• symplast pathway (through cytoplasm)
• apoplast pathway (through cell walls)
• vacuolar pathway (through cytoplasm & vacuole)

Question 7

what is a casparian strip

Answer 7

• an impermeable band around the endodermal cells forces water out the apoplast pathway.
• waterproof, mainly waxy substance (suberin)
• prevents toxic solutes moving into the plant.

Question 8

evidence for root pressure

Answer 8

• poisons, effect mitochondria and prevent production of ATP and causes root pressure to disappear.
• root pressure increases with temp suggesting chemical reactions are involved.
• xylem sap exudes frim cut at end of stem ay certain times.