7.9 Mass Flow Hypothesis

Question 1

What is translocation?

Answer 1

Mass flow of sucrose and amino acids from source to sink

Question 2

What are features of translocation?

Answer 2

Requires energy source to sink transport phloem water medium concentration gradient

Question 3

What is the mass flow hypothesis?

Answer 3

Translocation occurs due to pressure gradients

Question 4

How does mass flow hypothesis propose translocation occurs?

Answer 4

Solutes loaded water enters pressure increases solutes removed water leaves pressure decreases pressure gradient

Question 5

What happens at the sink in mass flow hypothesis?

Answer 5

Solutes actively unloaded

Question 6

What evidence supports mass flow hypothesis?

Answer 6

Ringing experiments radioactive tracers aphids metabolic inhibitors

Question 7

What evidence is against mass flow hypothesis?

Answer 7

Sugars don’t only move to highest water potential pressure gradient not high enough