The table gives statements about plant vascular tissues. Some apply to xylem vessels and some to phloem tubes.
Complete the table by using a tick (✓\checkmark✓) or a cross (×\times×) to show if each statement applies to xylem or to phloem. The first statement has been done for you.
StatementXylemPhloemtransport water and mineral ions✓×contain companion cellshave cell walls thickened with lignintransport substances via translocationcontain sieve platestransport substances in both upwards and downwards directions \begin{array}{|l|c|c|} \hline \textbf{Statement} & \textbf{Xylem} & \textbf{Phloem} \\ \hline \text{transport water and mineral ions} & \checkmark & \times \\ \hline \text{contain companion cells} & & \\ \hline \text{have cell walls thickened with lignin} & & \\ \hline \text{transport substances via translocation} & & \\ \hline \text{contain sieve plates} & & \\ \hline \text{transport substances in both upwards and downwards directions} & & \\ \hline \end{array} Statementtransport water and mineral ionscontain companion cellshave cell walls thickened with lignintransport substances via translocationcontain sieve platestransport substances in both upwards and downwards directionsXylem✓Phloem×Fusarium wilt is a vascular disease in tomato plants where fungal pathogens colonize and block the xylem vessels, narrowing the lumen and restricting the transport of water and mineral ions to the leaves.
Explain how the narrowing of xylem vessels is a disadvantage to a tomato plant growing in hot, dry, and windy conditions.
In humid, low-light environments, transpiration rates are significantly lower.
Suggest why a moderate narrowing of the xylem vessels has a much smaller effect on the survival of a plant growing in a deeply shaded rainforest understory than on a crop plant growing in an open, sunny field.
