GCSEScienceAQACombined Science: TrilogyBiologyRevision NotesOrganisationPlant Tissues, Organs & SystemsTranslocation

Translocation (AQA GCSE Combined Science: Trilogy: Biology): Revision Note

Exam code: 8464

Lára Marie McIvor

Written by: Lára Marie McIvor

Reviewed by: Dr Natalie Lawrence

Updated on

AQA Combined Science: Trilogy: BiologyAQA Biology

Translocation

  • Translocation can be defined as:

the movement of dissolved sugars through phloem tissue

  • Sugars may be transported upwards or downwards in the phloem:

    • Sugars travel from the leaves to the rest of the plant when photosynthesis is taking place

    • Sugars travel from storage organs to the rest of the plant when photosynthesis is not taking place

  • Sugars transported by translocation will either be used immediately by the plant or stored

Diagram of phloem tissue showing phloem cells and companion cells. Red arrows indicate sugars and amino acids moving upwards and downwards through the phloem.
Translocation is the movement of dissolved sugars (and amino acids) through the phloem

Comparing transport in the xylem and phloem

Tissue

What is Moved

Process

Direction of Flow

Xylem

Water and mineral ions

Transpiration stream

Unidirectional: from roots to leaves

Phloem

Dissolved sugars (sucrose)

Translocation

Bidirectional: either upwards or downwards

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Author
Reviewer
Lára Marie McIvor

Author: Lára Marie McIvor

Expertise: Content Creator

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.

Dr Natalie Lawrence

Reviewer: Dr Natalie Lawrence

Expertise: Content Writer

Natalie has a MCantab, Masters and PhD from the University of Cambridge and has tutored biosciences for 14 years. She has written two internationally-published nonfiction books, produced articles for academic journals and magazines, and spoken for TEDX and radio.