8.4Transport in Plants
Translocation Core — Cambridge IGCSE Biology 0610 Revision Notes & Topical Questions
5 min read 15 parts Lesson 7 of 9 Unit quiz
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
Lesson summary
8.4 Translocation — IGCSE BIOLOGY notes: Describe translocation of sucrose and amino acids in phloem from sources to sinks (Supplement).Sugars — Mainly sucrose, made from glucose produced in photosynthesis.Amino acids — Made using glucose and nitrates absorbed from the soil.Trans…
- Sieve plates
- Changing direction
- Cells — The tubes are made of living cells, unlike xylem vessels which are dead
- Source — A part of the plant where substances are made or released
- Sink — A part of the plant where substances are stored or used
- Direction — Substances always move from a source to a sink
Part 1 of 6What is translocated
Sugars
- Mainly sucrose, made from glucose produced in photosynthesis.
Amino acids
- Made using glucose and nitrates absorbed from the soil.
Translocation
- The transport of sucrose and amino acids in the phloem from regions of production to regions of storage or use.
Part 2 of 6Phloem tubes
Cells
- The tubes are made of living cells, unlike xylem vessels which are dead.
Sieve plates
- Cells are joined end to end with holes in the end walls that let substances flow from cell to cell.
Part 3 of 6Sources and sinks
Source
- A part of the plant where substances are made or released.
Sink
- A part of the plant where substances are stored or used.
Direction
- Substances always move from a source to a sink.
Changing direction
- The direction depends on the stage of development or the time of year.
Part 4 of 6Changes through the year
| Time | Source | Sink |
|---|---|---|
| Winter | Storage organs | Other parts of the plant, for respiration and repair |
| Spring growth | Storage organs such as roots | Growing areas |
| Summer | Photosynthesising leaves | Roots, where sucrose becomes glucose and is stored as starch |
Part 5 of 6Xylem and phloem compared
| Tissue | What is moved | Process | Direction | Cells |
|---|---|---|---|---|
| Xylem | Water and mineral ions | Transpiration stream | One way, roots to leaves | Dead |
| Phloem | Sucrose and amino acids | Translocation | All directions | Living |
Part 6 of 6More from the specification
Mesophyll
- The tissue in the middle of a leaf where photosynthesis takes place.
Movement
- An action by an organism or part of it causing a change of position or place.
Stomata
- Pores in the leaf through which water vapour leaves.
Humidity
- The amount of water vapour in the air.
Key terms
| Term | Meaning |
|---|---|
| Translocation | Movement of sucrose and amino acids in phloem from sources to sinks. |
| Source | A part of a plant that releases sucrose or amino acids. |
| Sink | A part of a plant that uses or stores sucrose or amino acids. |
| Sucrose | The sugar mainly transported in phloem. |
| Sieve plate | Perforated end wall of a phloem cell. |
| Phloem | Living tissue that transports sucrose and amino acids. |
Avoid these mistakes
1
Saying a plant part is always a source or always a sink — a storage organ can be both at different times.
2
Saying translocation moves only downwards — it moves from sources to sinks in any direction.
3
Saying phloem carries water and minerals — it carries sucrose and amino acids.
4
Calling phloem tubes dead — they are living cells.
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