Xylem and Phloem - Transport in Plants | Biology | FuseSchool

We could just say movement of water and minerals and movement of glucose and amino acids...

But this is science, and so we like to have special terms to describe these processes!

In these 3 part videos, we're going to look at the transport systems in plants for moving food, water and minerals around.

We have a beating heart and circulating blood, but what do plants do?

Cut a plant open, and it doesn't bleed. So what happens instead?

Plants have their own systems.

They have the Xylem which moves water and solutes from the roots to the leaves,

and the Phloem which moves glucose, made in the leaves by photosynthesis, and amino acids to the rest of the plant.

Here are the xylem and here are the phloem.

Notice how the arrangement is different in the stem and the roots.

The xylem and the phloem are found in groups called vascular bundles. And the position of these bundles changes for different parts of the plant.

Both the xylem and the phloem are made up of rows of cells that form a continuous tube, running the whole length of the plant.

The xylem vessels are made of elongated dead cells that are impermeable to water and have walls containing lignin (a woody material).

Because of this, xylem vessels are tough. Which is why the vascular bundles in the roots are in the centre.

They help prevent the plant being pulled out of the ground. They are also more protected in the centre.

Whereas the stem has to resist being squashed and bent,

and so it has the vascular bundles nearer to the edge to give the stem strength and support.

The phloem vessels are made up of living cells. They transport sucrose and amino acids up and down the plant,

depending upon where they are needed.

Whereas, in the xylem the movement is just one way: from the roots up to the leaves.

So we know that water and minerals go up the xylem, and amino acids and sucrose go up and down the phloem.

But how? In the second part of this video we are going to look at the xylem and transpiration.