transportation of plants

What is transpiration pull and how does it work?

When water evaporates from plants, water molecules stick together and pull the water from the roots down through the xylem creating a pressure like in a straw.

How is this attraction between water molecules called?

Cohesion

How does the xylem’s structure help transpiration pull?

The xylem is made of hydrophilic material, making water pass through easier, and the lignin on the wall makes the xylem tissue much stronger and resistant to the high pressure

How is the phloem tissue built?

It doesn’t have closed walls, more like a sieve, like this the phloem sap can move throughout the plant and come out where it’s needed the most.

How does osmosis favour the movement of the phloem sap?

The water from the nearby xylem moves into the phloem, more or less depending on the pressure in the region, increasing the pressure in the phloem more and more, with the biggest part of the sap going to the roots.