Skip to content
Dabour HubLEARN · PRACTICE · EXPLORESign inStudent

8.1Transport in Plants

Xylem and phloem — Cambridge IGCSE Biology 0610 Revision Notes & Topical Questions

5 min read 16 parts Lesson 4 of 9 1 quiz

📚 Cambridge IGCSE Biology 0610 Hub / Topical Revision
🩺
100% Curriculum Specification Match Lesson Doctor Verified
The only platform with 100% curriculum specification match and verified interactive question banks.
0%read
Lesson summary

8.1 Xylem and phloem — IGCSE BIOLOGY notes: State the functions of xylem and phloem, locate them in sections and relate xylem structure to function.Xylem — Transports water and mineral ions from the roots to the stem and leaves, and gives support.Phloem — Transports food material…

  • Arrangement
  • Seen in sections
  • General rule
  • No cross walls
  • No contents
  • Sieve tubes

Part 1 of 7Functions

Functions
Xylem
  • Transports water and mineral ions from the roots to the stem and leaves, and gives support.
Phloem
  • Transports food materials, mainly sucrose and amino acids, from photosynthesising leaves to non-photosynthesising parts of the roots and stem.

Part 2 of 7Vascular bundles

Arrangement
  • Xylem and phloem are arranged throughout the root, stem and leaves in groups called vascular bundles.
Seen in sections
  • Sections of non-woody dicotyledonous roots, stems and leaves show the position of each tissue.

Part 3 of 7Position in sections

General rule
  • Xylem is always on the inside and phloem is always on the outside.
Stem
  • Vascular bundles are arranged in a ring, xylem inner and phloem outer.
Root
  • Xylem forms a central star with phloem lying between its arms.
Leaf
  • Veins contain xylem on the upper side and phloem on the lower side.

Part 4 of 7Xylem vessels (Supplement)

Xylem vessels (Supplement)
Function
  • Transport tissue for water and dissolved mineral ions, which also supports the plant.
No cross walls
  • Cells are joined end to end with no cross walls to form a long continuous tube.
No contents
  • Cells are essentially dead, with no cell contents, so water passes freely.
Lignin
  • The walls are thickened with lignin, which strengthens the tubes and helps support the plant.

Part 5 of 7Phloem structure

1Sieve tubes
  • Living cells joined end to end with holes in the end walls called sieve plates.
2Flow
  • The holes allow easy flow of substances from one cell to the next.
3Companion cells
  • Cells beside each sieve tube that supply it with energy.

Part 6 of 7Xylem and phloem compared

TissueWhat is movedDirection of flowCells
XylemWater and mineral ionsOne way, roots to leavesDead
PhloemSucrose and amino acidsIn all directions, from source to sinkLiving

Part 7 of 7More from the specification

Mesophyll
  • The tissue in the middle of a leaf where photosynthesis takes place.
Transpiration stream
  • Continuous movement of water up the xylem from roots to leaves.
Transpiration
  • Loss of water vapour from leaves by evaporation and diffusion through stomata.
Vessel
  • A long tube formed from dead xylem cells.
Humidity
  • The amount of water vapour in the air.
Translocation
  • Movement of sucrose and amino acids in phloem from sources to sinks.

Key terms

TermMeaning
XylemVessels carrying water and mineral ions up the plant and supporting it.
PhloemTissue carrying sucrose and amino acids.
Vascular bundleA group of xylem and phloem vessels.
LigninSubstance thickening xylem walls.
Sieve platePerforated end wall between phloem cells.
Companion cellA cell that supplies energy to a sieve tube.

Avoid these mistakes

1
Saying xylem carries food — xylem carries water and mineral ions.
2
Mixing up the positions — xylem is on the inside and phloem on the outside.
3
Calling xylem cells living — mature xylem vessels are dead and hollow.
4
Saying phloem only moves substances downwards — it moves them in all directions.

Last updated:

\n