Who this is for: Cambridge IGCSE Biology (0610) students who want translocation — transport of assimilates in phloem — to become reliable marks instead of a confused “phloem carries water” answer.
What query it owns: how to understand and revise translocation in Cambridge IGCSE Biology.
Why this is safe: this page owns the translocation revision-guide angle, while Tutopiya’s Translocation subtopic page owns the learning resource and the free Translocation quiz owns the practice.

Translocation is the transport of sucrose and amino acids in the phloem from regions where they are made or stored (sources) to regions where they are used or stored (sinks). Cambridge IGCSE Biology (0610) tests whether you can define translocation, identify sources and sinks, and distinguish it from transpiration and xylem transport. This guide covers the syllabus definitions and the question types that appear every year.

Key takeaways

• Translocation is transport of sucrose and amino acids in phloem — not water.
• A source produces or releases assimilates (e.g. green leaves in daylight).
• A sink uses or stores assimilates (e.g. roots, fruits, growing tips).
• Direction can be up or down the plant depending on source and sink.
• Translocation is an active process requiring energy from respiration in companion cells.

What is translocation in Cambridge IGCSE Biology?

Translocation is the movement of dissolved organic substances — mainly sucrose and amino acids — through the phloem from a source to a sink. In daylight, leaves are the main source because photosynthesis produces sucrose. Sinks include growing regions (meristems), storage organs (roots, tubers) and developing fruits. Unlike xylem transport, phloem translocation can move substances in either direction depending on where sources and sinks are located.

You can read the full explanation, diagrams and notes on Tutopiya’s Translocation subtopic page before you attempt questions.

The core ideas you must master

Idea	What it means	How the exam uses it
Definition	Transport of sucrose/amino acids in phloem	”Define translocation”
Source	Region that supplies assimilates	”Identify the source in a diagram”
Sink	Region that receives assimilates	”State two sinks in a plant”
Substances	Sucrose and amino acids	”State what is translocated”
Energy	Active process, needs respiration	”Explain why translocation needs energy”

Sources and sinks — examples for exam answers

Part of plant	Role in daylight	Role at night / in spring
Green leaves	Source (photosynthesis)	May become sink if no light
Roots	Sink (growth, storage)	Source (stored starch converted to sucrose)
Growing tips / buds	Sink (cell division, growth)	Sink
Fruits / seeds	Sink (development)	Sink
Storage tubers (e.g. potato)	Sink	Source when sprouting

Translocation in past-paper wording: command words that matter

Command word / phrase	What the question wants	Typical translocation stem
Define	Precise syllabus definition	”Define the term translocation.”
State	Short factual answer	”State two substances translocated in phloem.”
Explain	Cause and effect	”Explain why translocation requires energy.”
Identify	Name source or sink	”Identify the source of sucrose in a leaf.”
Compare	Differences from xylem transport	”Compare translocation and transpiration.”

Worked exam-style stems (how to answer the wording)

1. “Define the term translocation.” Translocation is the transport of sucrose and amino acids in the phloem from a source to a sink. Mark-scheme reward: sucrose/amino acids, phloem, source to sink.
2. “State two sinks for translocated sucrose.” Any two from: roots, growing tips, fruits, seeds, storage organs. Reward: named sinks, not vague “rest of plant”.
3. “Explain why translocation is an active process.” Substances are moved against a concentration gradient; energy from respiration in companion cells is required. Reward: against gradient + energy from respiration.

When you can recognise the wording instantly, work the full set on the Transport in Plants topical past paper questions and the Translocation quiz.

How translocation connects to the rest of the syllabus

Translocation occurs in Phloem and depends on photosynthesis (sucrose production in leaves). It contrasts with Transpiration (water loss) and xylem transport. Use Translocation of Food flashcards for active recall. The Cambridge IGCSE Biology resource hub links every Transport in Plants subtopic.

Common mistakes students make

• Saying translocation transports water — that is xylem/transpiration.
• Using “food” instead of sucrose and amino acids.
• Saying phloem only transports downward — direction depends on source and sink.
• Confusing translocation with transpiration — completely different processes.
• Omitting that translocation requires energy from respiration.

When you need more support

If translocation questions keep costing marks — especially source/sink identification — work through the Transport in Plants topical past paper questions and the Translocation quiz, then get focused help from a Cambridge IGCSE Biology tutor.

Frequently asked questions

Is translocation hard in Cambridge IGCSE Biology? The main challenge is distinguishing it from transpiration and naming specific substances, not just “food”.

What is the difference between translocation and transpiration? Translocation moves sucrose and amino acids in phloem; transpiration is loss of water vapour from leaves through stomata.

Can translocation move substances upward? Yes — phloem transport direction depends on where the source and sink are, not fixed upward or downward.

How do I revise translocation effectively? Learn the definition, practise source/sink examples, compare with xylem transport, then take the Translocation quiz.

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