Phloem

What process allows sucrose to diffuse into companion cells from source cells?

Facilitated diffusion.

What ions are actively transported into the cell walls of companion cells?

Hydrogen ions (H+).

Through what mechanism is sucrose transported along with hydrogen ions in sieve tube elements?

Co-transport proteins.

What happens to the water potential when sucrose concentration increases in the sieve tube elements?

It lowers the water potential.

What causes water to move from the xylem into the phloem?

High sucrose concentration in the phloem creates a lower water potential.

What is the result of water moving into the phloem due to high sucrose concentration?

Increased hydrostatic pressure.

How is sucrose used in sink cells after it is transported there?

It is used up for respiration or starch production.

How does sucrose enter sink cells?

By co-transport down the concentration gradient.

What effect does sucrose uptake in sink cells have on their water potential?

It lowers the water potential in the sink cells.