OrganisationDefinitions

Key Definitions

Part of Transpiration · GCSE GCSE Biology revision

This definitions covers Key Definitions within Transpiration for GCSE Biology. Transpiration process, stomatal control, factors affecting rate, plant adaptations, measuring transpiration, and practical investigations It is section 14 of 21 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.

Topic position

Section 14 of 21

Practice

21 questions

Recall

25 flashcards

Key Definitions

Transpiration: The evaporation of water from the surfaces of mesophyll cells inside the leaf, followed by diffusion of water vapour through air spaces and out via open stomata into the surrounding air.

Transpiration stream: The continuous movement of water through a plant — from soil, through root hair cells by osmosis, across the root cortex, up through xylem vessels, and out through stomata via transpiration.

Stomata (singular: stoma): Pores in the leaf epidermis through which gas exchange and water vapour loss occur. Opened and closed by guard cells.

Guard cells: Pairs of kidney-shaped cells flanking each stoma. Changes in their turgor pressure (controlled by potassium ion movement) open and close the stomatal pore.

Potometer: An apparatus used to measure the rate of water uptake by a cut plant shoot. It measures water uptake, which is approximately equal to (but not identical to) the transpiration rate.

Xerophyte: A plant adapted to survive in an environment with very little water, such as a desert. Xerophytes typically have structural and physiological adaptations to reduce the rate of transpiration.

Wilting: Loss of rigidity (turgor) in plant cells when the rate of transpiration exceeds the rate of water uptake from the soil, causing cells to become flaccid.

Keep building this topic

Read this section alongside the surrounding pages in Transpiration. That gives you the full topic sequence instead of a single isolated revision point.

How It Works: Why Environmental Factors Change Transpiration Rate Common Misconceptions The Hidden Power of Water Loss Key Facts About Transpiration

Practice Questions for Transpiration

What is transpiration?

A. The evaporation of water from plant leaves through stomata
B. The movement of sugars through phloem
C. The absorption of water by root hair cells
D. The process of photosynthesis in leaves

1 markfoundation

Describe the three stages of transpiration in a leaf.

3 marksstandard

Quick Recall Flashcards

What is a xerophyte?

A plant adapted to survive in dry/arid conditions with limited water availability (e.g., cacti, marram grass).

What is a potometer?

An apparatus that measures the rate of water uptake by a plant shoot. Used to estimate transpiration rate (though actually measures uptake, not loss).

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How It Works: Why Environmental Factors Change Transpiration Rate

Common Misconceptions