Translocation
| English | Chinese | Pinyin |
|---|---|---|
| translocation | 转运 | zhuǎn yùn |
| sources | 源 | yuán |
| sinks | 库 | kù |
| tuber | 块茎 | kuài jīng |
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:
Translocation moves sugars in the phloem.
Translocation takes place in the ______.
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:
Sources supply sugar; sinks use or store it.
Which is acting as a sink?
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.
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