Unloading of assimilates (eg. sucrose

Question 1

The unloading of the assimilates (eg. sucrose) occurs at the

Answer 1

sinks

Question 2

Scientists believe that the unloading of sucrose is similar to the loading of sucrose, with the sucrose being

Answer 2

actively transported out of the companion cells and then moving out of the phloem tissue via apoplastic or symplastic pathways

Question 3

To maintain a concentration gradient in the sink tissue,

Answer 3

sucrose is converted into other storage molecules such as starch. This is a metabolic reaction so requires enzymes (eg. invertase which hydrolyses sucrose into glucose and fructose)

Question 4

The intracellular space and walls of the sieve cells are adapted for the mass transport of sugars

how

Answer 4

There are very few organelles, a small volume of cytoplasm and a large vacuole present in the intercellular space

The phloem sap can flow easily by moving through the open corridor that has low resistance

Sieve cells have thick cell walls
These walls help them to withstand the pressure exerted by the mass flow of sugars

Question 5

Remember that the loading of sucrose requires two protein pumps (,,,,,,,,,,,]) which are located in the companion cell surface membrane.

Answer 5

proton and co-transporter