Plant tissues, transport and water loss
Connect root, leaf and stem structures to absorption, transport, photosynthesis, storage and transpiration.
Exam scope and assessment notes
Use this original lesson for the listed 2026, 2027–2028 and 2029–2031 Cambridge syllabus cycles. This route maps Cambridge's 2026 Version 2, 2027–2028 Version 1 and 2029–2031 Version 1 syllabuses. The 2026 update changes only a weblink; Cambridge reports no significant teaching changes for the 2027–2028 or 2029–2031 cycles. Exams are in the November series, and the qualification is not available in every administrative zone; confirm entry with your centre. Centre-selected local crop, weed, pest, disease and livestock examples must be checked against local agriculture. StudyForA does not replace supervised, risk-assessed practical work, the four assessed practical exercises, the individual practical investigation/report, teacher assessment or Cambridge moderation. Online practice is not an official mark or grade.
Before you begin
- Read the syllabus that matches your exam year and confirm your centre can enter you for code 0600. This route maps Cambridge's 2026 Version 2, 2027–2028 Version 1 and 2029–2031 Version 1 syllabuses. The 2026 update changes only a weblink; Cambridge reports no significant teaching changes for the 2027–2028 or 2029–2031 cycles. Exams are in the November series, and the qualification is not available in every administrative zone; confirm entry with your centre. Centre-selected local crop, weed, pest, disease and livestock examples must be checked against local agriculture. StudyForA does not replace supervised, risk-assessed practical work, the four assessed practical exercises, the individual practical investigation/report, teacher assessment or Cambridge moderation. Online practice is not an official mark or grade.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which tissue carries most water and dissolved mineral salts upward?
What you will learn
- Explain roots, root hairs, diffusion, osmosis and vascular transport.
- Relate leaf and dicot stem structures to function, gas exchange and photosynthesis.
- Explain translocation, storage organs and transpiration and predict how conditions affect water loss.
Roots absorb and transport materials
Root hairs provide a large surface area in contact with soil water. Water enters root cells by osmosis across a partially permeable membrane when water potential is higher outside than inside; mineral ions may enter by diffusion or other uptake processes.
Xylem transports water and dissolved mineral salts through the plant. Root tissue organisation helps move materials toward vascular tissue; the syllabus does not require detailed cell ultrastructure.
Leaves and stems exchange and move materials
A leaf's broad surface receives light; veins contain transport tissue, and stomata allow gas exchange by diffusion. Carbon dioxide enters and oxygen can leave; guard cells regulate stomatal opening. Photosynthesis uses carbon dioxide and water, with light and chlorophyll, to make carbohydrates and release oxygen.
In a dicot stem, vascular tissues transport materials; xylem carries water and mineral salts, while phloem transports synthesised food. Translocation is movement of synthesised food to storage or growing parts.
Storage and transpiration
Roots, stems, fruits and seeds may be modified as storage organs. Stored materials include carbohydrates, oils and proteins; the plant part and crop determine the form.
Water evaporates from moist cell surfaces and water vapour diffuses through stomata. The resulting transpiration stream draws water through the plant. Higher temperature, wind and light can increase transpiration; high humidity reduces the diffusion gradient. These effects depend on plant and conditions.
Sources for this lesson
Pause and explain
Which tissue carries most water and dissolved mineral salts upward?
Worked example
On a hot, dry and windy afternoon, predict what may happen to transpiration and explain two linked steps from soil water to a leaf.
Show the worked solution
- Higher temperature and wind can increase transpiration, while low humidity may strengthen water-vapour diffusion out of the leaf.
- Water enters root hairs by osmosis and moves through root tissues to xylem.
- Xylem carries water upward; evaporation from leaf surfaces and diffusion through stomata contribute to water loss.
Answer Transpiration may rise, increasing the demand for water uptake. Plant response also depends on soil water, stomatal behaviour and species.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Explain the pathway of water from soil into a plant and out through a leaf.
Give me a hint
Use osmosis, xylem, evaporation and stomatal diffusion in order.
Compare my reasoning
- Water enters root hairs from soil by osmosis and moves through root tissues.
- Xylem carries water through the stem to leaf veins and tissues.
- Water evaporates from moist leaf surfaces and diffuses as vapour through stomata.
Water is absorbed by roots, transported in xylem, then evaporates and diffuses through leaf stomata. This flow contributes to transpiration.
Look for these in your work
- Correct sequence
- Tissue named
- Evaporation and diffusion distinguished
A student covers some leaves with a clear bag and observes droplets. Explain the likely source and name one limitation of this observation.
Give me a hint
Consider water vapour leaving the plant and condensing; avoid confusing it with guttation without further evidence.
Compare my reasoning
- Water vapour can leave leaves through stomata during transpiration.
- The bag traps vapour, which may condense into visible droplets on a cooler surface.
- The observation does not by itself quantify transpiration or rule out other moisture sources; use a controlled comparison.
The droplets are consistent with transpired water vapour condensing. A control and measurement are needed to establish amount and exclude other sources.
Look for these in your work
- Source linked to transpiration
- Condensation explained
- Evidence limitation stated
A crop wilts in hot wind despite irrigation. Give two physiological explanations and two measurements to investigate.
Give me a hint
Separate water loss from uptake and assess soil, plant and atmospheric conditions.
Compare my reasoning
- Heat and wind can raise water loss through transpiration.
- Root uptake may not keep pace if soil water is unavailable, roots are damaged or water movement is restricted.
- Measure soil moisture and weather conditions; also inspect plant water status, roots and irrigation delivery.
Wilting may occur when water loss exceeds uptake, but heat, wind, soil water, roots and irrigation delivery all need checking before choosing a response.
Look for these in your work
- Loss and uptake distinguished
- Two explanations stated
- Relevant measurements proposed
Common mistakes
- Calling water movement through phloem transpiration
- Confusing translocation of food with transport of water in xylem
- Saying photosynthesis occurs without light
- Treating every environmental effect as identical for every plant
What can you explain now?
Which tissue carries most water and dissolved mineral salts upward?
Compare with the explanation
Xylem
Xylem transports water and mineral salts through the plant.
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Make it stick
Define translocation and transpiration, then distinguish their materials and routes.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.