Question

According to the pressure–flow model of movement of phloem contents, photosynthate movement from source to sink is driven by

• A. an ATP–dependent pressure–flow pump
• B. a water–pressure potential gradient
• C. transpiration
• D. a pH gradient

Answer 1

The correct option is B a water–pressure potential gradient

According to the pressure-flow model of the movement of phloem contents from source to sink is driven by a water pressure potential gradient. The hydrostatic pressure increases in phloem which initiates pressure flow. This makes the sap flows through the phloem.