Cambridge IGCSE Biology 0610 · Topic 8
Transport in Plants
A plant absorbs water and mineral ions at its roots, but it needs them everywhere — in the leaves, in the growing tips, in the flowers. It also makes sugars in its leaves through photosynthesis, but plenty of the plant’s tissue is nowhere near a leaf. Transport in plants is really the story of how two separate tissues solve those two separate delivery problems, and almost every mark in this chapter depends on you keeping the two stories apart rather than blending them into one generic ‘stuff moves around the plant’ answer.
Cambridge splits this chapter into four syllabus points — 8.1 Xylem and phloem, 8.2 Water uptake, 8.3 Transpiration and 8.4 Translocation — and they build on each other in a fairly linear way. You start by learning what the two transport tissues are and where to find them, then follow water on its actual journey from soil to leaf, then look at what happens to that water once it reaches the leaf and why that loss matters, and finally turn to the completely separate phloem system that moves sugars and amino acids wherever the plant currently needs them.
The biggest source of lost marks across this whole chapter is not missing facts — it’s answering a xylem question with phloem language, or the reverse. Xylem carries water and mineral ions, upward, and that movement is tied to transpiration. Phloem carries sucrose and amino acids, in whichever direction the current sources and sinks demand. The pages below are written to keep that boundary sharp, section by section, rather than papering over it with vague “transport substances around the plant” phrasing that an examiner won’t credit.
What’s in this chapter
| Page | Level | What it covers |
|---|---|---|
| Xylem and phloem | Core + Supplement | What each tissue actually transports, where to find them in a root, stem or leaf section, and the three structural features that make a xylem vessel work. |
| Water uptake | Core | Root hair cells, the exact four-stage pathway water follows to a leaf, and the coloured-stain experiment that makes that pathway visible. |
| Transpiration | Core + Supplement | The evaporation-then-diffusion mechanism behind water loss, why transpiration pulls water up the xylem, and why plants wilt. |
| Factors affecting transpiration | Core + Supplement | Temperature, wind speed and humidity explained mechanistically, plus the potometer method Cambridge expects you to describe. |
| Translocation | Supplement | How sucrose and amino acids move through phloem from sources to sinks — and why the same organ can be either, depending on when you ask. |
Core or Supplement?
Xylem and phloem functions and positions, root hair uptake, the water pathway, the stain investigation, transpiration’s basic definition, and investigating temperature and wind speed with a potometer are all Core, so every candidate needs them regardless of tier. Xylem vessel structure, the internal surface-area explanation for water loss, transpiration pull, wilting, the full mechanistic explanation of temperature, wind speed and humidity, and the whole of translocation are Supplement only, required for the Extended paper. If you’re not sure which tier you’re sitting, that’s worth checking before you spend time on the Supplement sections — none of the Core content in this chapter depends on them.