Explain why plants need both xylem and phloem vessels, referring to the substances transported in each.

Xylem and phloem are both essential for plant survival because they transport different substances that are required in different parts of the plant.

Xylem vessels move water and dissolved mineral ions from the roots up to the leaves and other shoots. The water is required for photosynthesis in the leaves and to maintain cell turgor, which keeps the plant upright.

Phloem vessels carry sugars, mainly glucose, produced in the leaves during photosynthesis to all other tissues. These sugars are used for respiration and for growth in non‑photosynthesising parts such as roots, growing tips and storage organs.

Thus, xylem supplies the water and minerals needed for photosynthesis and turgidity, while phloem distributes the sugars produced, allowing the plant to grow and function throughout its body.