Translocation
Introduced| English | Meaning |
|---|---|
| translocation/trænsləʊˈkeɪʃn/ | The transport of sugars (and amino acids) in the phloem. |
| sources/ˈsɔːsɪz/ | sources |
| sinks/sɪŋks/ | A region of a plant that uses or stores assimilates delivered by phloem transport. |
| tuber/ˈtjuːbə/ | A sink (storing starch). |
Delivering the sugar
- Leaves make sugar by photosynthesis — but the whole plant needs it.
- Moving that sugar to where it's needed is translocation 转运.
Translocation is the transport of:
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Translocation moves sugars in the phloem.
Translocation takes place in the ______.
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Phloem carries sugars; xylem carries water.
What translocation is
- Translocation is the transport of sugars (and amino acids) in the phloem.
- It moves food from sources 源 (where it's made or stored) to sinks 库 (where it's used).
Translocation: the phloem carries sugars from a source (leaf) to a sink (root or fruit)
Translocation in the phloem
Phloem carries dissolved sugars from where they are made (the source) to where they are used or stored (the sink).
A "source" in translocation is a part that:
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Sources supply sugar; sinks use or store it.
Which is acting as a sink?
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A growing fruit uses sugar, so it is a sink.
Sources and sinks
- A source makes or releases sugar (e.g. a leaf in summer, a storage root in spring).
- A sink uses or stores sugar (e.g. growing shoots, fruits, roots).
Phloem can carry sugar both up and down the plant, depending on need.
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Direction depends on where the sources and sinks are.
Why both directions
- Because sources and sinks change, phloem carries sugar up or down as needed.
- In summer a leaf is a source; a potato tuber 块茎 is a sink (storing starch).
Worked example. In spring, a potato's stored starch becomes a source, sending sugar up to the growing shoots (sinks). In summer, the leaves are sources sending sugar down to refill the tuber.
You've got it
- translocation = transport of sugars in the phloem
- it moves food from sources (made/stored) to sinks (used/stored)
- direction changes with the season — phloem carries sugar either way