Transport in Plants — Transpiration

This lesson covers the transpiration stream and the role of xylem in transporting water and mineral ions through a plant, as required by the Edexcel GCSE Combined Science specification (1SC0). You need to understand how water moves from roots to leaves and the factors that affect the rate of transpiration.

---

Why Do Plants Need a Transport System?

Plants need to move substances around their bodies, but they do not have a circulatory system like animals. Instead, they have two types of specialised transport tissue:

Tissue	What it transports	Direction
Xylem	Water and dissolved mineral ions	Roots → leaves (upward only)
Phloem	Dissolved sugars (sucrose) and amino acids	Source → sink (up or down)

This lesson focuses on xylem and the transpiration stream. Phloem and translocation are covered in Lesson 4.

---

Xylem Structure

Xylem vessels are dead, hollow tubes that form a continuous pipeline from roots to leaves.

Key structural features: