Translocation

Question 1

What is moved in translocation?

Answer 1

Sucrose and ammino acids.

Question 2

What is the role of companion cells and how are they specialised?

Answer 2

-Helps phloem carry out function as they lose, help with transport, respiration and active transport. lots of organelles.
-Has lots of RER, ribosomes and mitochondria.

Question 3

What is the process of transloaction?

Answer 3

-Solutes are actively transported from the source to the sieve tubes by companion cells.
-Water potential in sieve cells decreases so water moves into phloem from the xylem and companion cells.
-Hydrostatic pressure rises at the source end of the phloem.
-At the sink end solutes are removed from the phloem and used up which increases water potential inside sieve cells so water leaves by osmosis.
-As water leaves pressure falls at the sink end.
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Question 4

What evidence can support the mass flow hypothesis?

Answer 4

-If a metabolic inhibitor is put in phloem no ATP is produced and no sugar moved into phloem.

Question 5

What evidence goes against the mass flow hypothesis?

Answer 5

-sieve cells need to be under a very high pressure to be able to move solute through he small holes.
-Travels to too many sinks at once, not just the one with the highest water potential.

Question 6

What is the phloem made out of?

Answer 6

Living cells