Translocation (Cambridge (CIE) O Level Biology) : Revision Note

Naomi Holyoak

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Translocation

  • The soluble products of photosynthesis are sugars and amino acids

  • These are transported around the plant in the phloem

    • Sugars are transported in the form of sucrose

  • The transport of sucrose and amino acids in the phloem, from regions of production to regions of storage or use, is known as translocation

  • Translocation involves the transport of dissolved substances from a source to a sink inside a plant

    • A source is the part of a plant that supplies sucrose and amino acids

    • A sink is where sucrose and amino acids will be used or stored

  • Transport in the phloem occurs in different directions depending on the stage of development or the time of year

Sources and sinks table

Region

Definition

Examples

Source

The part of a plant that supplies sucrose and amino acids

A photosynthesising leaf during summer will produce sugars which can be transported to other parts of the plant

A storage organ in the roots, e.g. a potato tuber, during early spring will break down starch to produce sugars; this will fuel the growth of new leaves

Sink

The part of a plant that uses or stores sucrose and amino acids

A leaf bud during early spring will not yet be photosynthesising, so will need a supply of sugars from a storage organ

A storage organ in the roots during the summer; leaves will produce more sugars than they need at this time of year, so excess sugars can be stored

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Naomi Holyoak

Author: Naomi Holyoak

Expertise: Biology

Naomi graduated from the University of Oxford with a degree in Biological Sciences. She has 8 years of classroom experience teaching Key Stage 3 up to A-Level biology, and is currently a tutor and A-Level examiner. Naomi especially enjoys creating resources that enable students to build a solid understanding of subject content, while also connecting their knowledge with biology’s exciting, real-world applications.