The scientists concluded that phloem tissue in the heat-treated plant stopped transporting substances.

Explain how the evidence supports this conclusion.

Use information from Figure 9 and Table 4 in your answer.

The scientists then investigated the effect of heat treatment on the movement of water through the xylem of barley plants. They found that water still moved through the heated part of the leaves of heat-treated plants. However, the rate of movement was slower.

Suggest two reasons why water still moved through the heated part of the leaves.

The scientists then investigated the movement of iron ions (Fe3+) from the soil to old and young leaves of heat-treated barley plants and to leaves of plants that were not heat treated. Heat treatment was applied half way up the leaves. The scientists determined the concentration of Fe3+ in the top and lower halves of the leaves of each plant.

Their results are shown in Figure 10.

What can you conclude about the movement of Fe3+ in barley plants?

Use all the information provided.