movement of solutes

1. nitrate ions

2. phosphate ions

3. sulphate ions

4. magnesium ions

5. calcium ions

1. to make amino acids, proteins and nucleic acids

2. to make phospholipids, nucleic acids and ATP

3. to make the amino acids cysteine and methionine

4. to make chlorophyll

5. to make calcium pectate for the middle lamella of cell walls

how are these ions transported into the plant

Ions are absorbed from the soil mainly by active transport, though facilitated diffusion may also be used under certain circumstances

what’s the evidence for ions being transported like this

1. The concentrations of ions inside root cells are up to 100 times greater than in the soil, so they are being transported up their concentration gradient.

2. Different ions are taken up at different rates and by different amounts. This means the process is selective, which suggests that different membrane pumps are involved.

3. If respiratory inhibitors such as cyanide are applied to living roots, ion uptake is greatly reduced, since there is no ATP being made to drive the membrane pumps. Any remaining uptake must be passive.

4. The active uptake of ions is partly responsible for the water potential gradient in roots, and therefore for the uptake of water by osmosis.

how ions physically move into the xylem

Ions are transported through plants with water. They diffuse down their concentration gradient through the root to the xylem, where they are loaded into the xylem by active transport. Ions travel up the xylem by mass flow as the water is pulled up the stem (in other words they are simply carried up in the current of the xylem solution). In the leaves they are selectively absorbed into the surrounding cells by active transport using ATP made in the phloem companion cells.

what is glucose transported into and why

its transported into sucrose as its less reactive

what’s translocation

The phloem contains a very concentrated solution of dissolved solutes, called the sap, and the transport of solutes in the phloem is called translocation.

what is a source

where sugar is made

what is a sink

where sugar goes

what happens with sugar in a plant in summer

In the summer most of the sugar moves from the leaves where it is made into the roots wear it is stored

what happens in spring in a plant in summer

sugar is transported from the roots to the growing buds

describe mass flow in the plant

1.      In the leaves sucrose is loaded into the phloem vessels by active transport by the companion cells. This decreases the water potential in the leaf phloem.

2.      In the leaves ions are also actively transported out of the xylem vessels into leaf cells, which increases the water potential of the leaf xylem.

3.      Water in the leaves therefore diffuses from xylem vessels to phloem vessels by osmosis, down its water potential gradient. 

4.      This osmosis increases the hydrostatic pressure in the phloem, so water and dissolved solutes are forced downwards to relieve the pressure. This is mass flow: the flow of water together with its dissolved solutes due to a force.

5.      In the roots sucrose is unloaded from the phloem either by diffusion or by active transport into the cells of the root.

6.      At the same time, ions are being pumped into the xylem from the soil by active transport, reducing the water potential in the xylem.

7.      The xylem now has a lower water potential than the phloem, so in the roots water diffuses by osmosis from the phloem to the xylem.

8.      Water and its dissolved ions are pulled up the xylem by tension from the leaves. This is also mass flow.