Who this is for: Cambridge IGCSE Biology (0610) students who want transpiration — loss of water vapour from leaves and its role in moving water up xylem — to become a reliable source of marks instead of a vague definition mixed up with translocation.
What query it owns: how to understand and revise transpiration in Cambridge IGCSE Biology (0610).
Why this is safe: this page owns the transpiration revision-guide angle, while Tutopiya’s Transpiration subtopic page owns the learning resource and the free Transpiration quiz owns the practice.

Transpiration is one of the most frequently tested processes in the Transport in Plants unit of Cambridge IGCSE Biology (0610). Whenever a question involves water loss from stomata, wilting, potometer experiments, or factors that change transpiration rate — examiners expect a precise definition and a clear explanation of transpiration pull. This guide explains exactly what transpiration covers, how to handle the question types that actually appear, and where to practise each skill.

Key takeaways

• Transpiration is the loss of water vapour from aerial parts of a plant, mainly through stomata in leaves.
• Transpiration pull draws water up xylem as water evaporates from mesophyll cell walls into air spaces and diffuses out through stomata.
• Temperature, humidity, wind and light affect the rate; state each with a biological reason in explain questions.
• Wilting occurs when water loss by transpiration exceeds water uptake by roots.
• Always separate transpiration from translocation (sugars in phloem) and guttation (liquid water droplets — not on core syllabus but sometimes confused).

What is transpiration in Cambridge IGCSE Biology?

Transpiration is the loss of water vapour from the aerial parts of a plant, especially through stomata in leaves. In Cambridge IGCSE Biology (0610) it creates a pull on the column of water in xylem — the transpiration stream — drawing water from roots to leaves to replace water that evaporates from mesophyll surfaces. It is essential for transporting minerals and for cooling the leaf, but excessive transpiration can cause wilting.

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

The core ideas you must master

Idea	What it means	How the exam uses it
Evaporation from mesophyll	Water evaporates from cell walls into air spaces	”Describe the pathway of water through a leaf.”
Diffusion through stomata	Water vapour exits when stomata are open	”Explain the role of stomata in transpiration.”
Transpiration pull	Tension pulls water up xylem	”Explain how water moves up the stem.”
Factors affecting rate	Temperature, humidity, wind, light	”Explain how wind affects transpiration.”
Wilting	Loss exceeds uptake	”Explain why a plant wilts on a hot day.”

How to answer transpiration questions — step by step

1. Define transpiration — loss of water vapour from aerial parts, mainly stomata.
2. Describe the leaf pathway — xylem → mesophyll cells → evaporation from cell walls → air spaces → stomata → atmosphere.
3. Explain transpiration pull — evaporation creates tension → water pulled up xylem → cohesive water column (optional at IGCSE: cohesion-tension).
4. For factor questions — name factor → effect on evaporation/diffusion gradient → faster or slower transpiration.
5. For experiments — potometer measures water uptake (related to transpiration rate).
6. Check you have not described translocation — that is sugar transport in phloem.

Test yourself with the free Transpiration quiz after working through explain stems.

Factors affecting transpiration rate

Factor	Effect on rate	Biological reason
Higher temperature	Increases	More kinetic energy → faster evaporation
Lower humidity	Increases	Steeper water vapour concentration gradient outside leaf
Wind / air movement	Increases	Removes humid air at leaf surface → maintains gradient
Bright light	Increases	Stomata open → more water vapour escapes
Closed stomata	Decreases	Less pathway for water vapour to leave

Transpiration in past-paper wording: command words that matter

Command word / phrase	What the question wants	Typical transpiration stem
Define	Precise meaning	”Define transpiration.”
Describe	Sequence or observations	”Describe how water is lost from a leaf.”
Explain	Mechanism + reason	”Explain how transpiration pulls water up the xylem.”
Suggest	Apply to context	”Suggest why a plant wilts in dry, windy conditions.”
Compare	Differences	”Compare transpiration and translocation.”

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

1. “Define transpiration.” Loss of water vapour from the aerial parts of a plant (mainly through stomata in leaves). Mark-scheme reward: water vapour + aerial parts + stomata.
2. “Explain how transpiration causes water to move up the stem.” Water evaporates from mesophyll → lower pressure in xylem → transpiration pull draws water up from roots → continuous column in xylem. Reward: evaporation + pull/tension + xylem.
3. “Explain how an increase in wind speed affects transpiration.” Wind removes water vapour near leaf surface → maintains steep concentration gradient → faster diffusion of water vapour through stomata → increased transpiration rate. Reward: gradient + faster loss.

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

How transpiration connects to the rest of Biology (0610)

Transpiration links water uptake in roots to xylem structure and leaf structure (stomata, spongy mesophyll). It connects to diffusion (water vapour out of stomata) and contrasts with translocation in phloem. When you are ready to mix topics, the Cambridge IGCSE Biology resource hub lets you move from transpiration into translocation or any weak subtopic.

Common mistakes students make

• Defining transpiration as loss of liquid water — it is water vapour.
• Saying transpiration happens in roots — mainly leaves (aerial parts).
• Confusing transpiration with translocation.
• Forgetting to link stomata to the pathway in describe questions.
• In factor questions, stating an effect without explaining the gradient or evaporation.

When you need more support

If transpiration questions keep tripping you up — especially transpiration pull or factor explanations — work through the Transport topical past paper questions and the Transpiration quiz, then get focused help from a Cambridge IGCSE Biology tutor.

Frequently asked questions

Is transpiration hard in Cambridge IGCSE Biology? The definition is straightforward. Marks are lost on transpiration pull explanations and factor questions without biological reasons.

What is the quickest way to define transpiration in an exam? Loss of water vapour from aerial parts of a plant, mainly through stomata.

Does transpiration only happen during the day? Rate is highest when stomata are open in light; some water loss can occur at night if stomata remain partially open.

How do I revise transpiration effectively? Read the subtopic notes, practise the leaf pathway and factor explains, then take the Transpiration quiz.

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