7.8 Transport of organic molecules in the phloem

Question 1

what is the movement of glucose in the plant?

Answer 1

translocation

Question 2

what happens at the source during translocation?

Answer 2

• H+ ions move from the companion cell to the palisade cell
• increasing H+ ion conc
• sucrose diffuses to companion cell with H+ ions

Question 3

how does sucrose move into the companion cell?

Answer 3

by co-transport with the H+ions

Question 4

how do H+ ions move into the palisade cell at the source?

Answer 4

actively using ATP

Question 5

what happens after sucrose moves into the companion cell?

Answer 5

• sucrose diffuses into sieve tube element
• decreasing water potential
• causing water to move from xylem into the sieve tube element
• increasing hydrostatic pressure

Question 6

what happens to sucrose at the sink?

Answer 6

• sucrose actively transported into the sink
• sucrose converted into starch or used in respiration

Question 7

what happens at the sink after the sucrose moves into the companion cell?

Answer 7

• water potential increases
• water moves back into the xylem
• decreasing hydrostatic pressure
• sucrose moves by mass flow down the hydrostatic conc gradient from source to sink