How to Revise IGCSE Biology Topic 8: Transport in Plants
Biology editorial review is supported by the
named review panel.
Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Key point
Compare xylem and phloem (substance, direction, cell status, energy). Know the four factors affecting transpiration. Understand root hair cell absorption (osmosis for water, active transport for minerals).
Topic 8 covers how water and minerals move up through xylem (transpiration) and how sugars move through phloem (translocation). Key exam areas include comparing xylem and phloem, factors affecting transpiration rate, and potometer experiments.
Priority 1: Xylem vs phloem
Xylem: transports water and mineral ions upward. Dead cells, hollow, lignin-thickened walls. Passive: driven by transpiration pull. Phloem: transports dissolved sugars (sucrose) both up and down (source to sink). Living sieve tube elements with companion cells. Active: requires energy.
Priority 2: Transpiration and its factors
Transpiration is the loss of water vapour from leaves through stomata. Four factors affect the rate: temperature (higher → faster evaporation), humidity (lower → steeper gradient → faster), wind (removes humid air → steeper gradient), light intensity (stomata open wider in light).
Priority 3: Root hair cells
Root hair cells absorb water by osmosis (soil water is more dilute than cell sap) and mineral ions by active transport (minerals are more concentrated inside the root hair cell). Root hairs increase surface area for absorption.
Frequently asked questions
What is the difference between transpiration and translocation?
Transpiration = water loss from leaves via stomata (passive, upward in xylem). Translocation = sugar transport from source to sink (active, both directions in phloem).
Put the guide into practice
Questions and practical resources
Use a fresh question to check whether the idea can be applied without prompts.