Class 10 Science - ICSE-BIOLOGY
Transpiration
The chapter 'Transpiration' in Class 10 ICSE Biology explores the loss of water in the form of water vapour from the aerial parts of plants, mainly through stomata. You will learn about the mechanism of stomatal opening and closing, the factors affecting the rate of transpiration, and the adaptations in plants to reduce water loss. The chapter also details experimental setups like Ganong's potometer and highlights the significance of transpiration, often referred to as a 'necessary evil'. This is a high-scoring topic in board exams, frequently featuring direct theoretical questions, diagram-based questions, and experimental reasoning.
Start Learning FreeKey Concepts
Transpiration
The biological process by which water is lost in the form of water vapour from the aerial parts of living plants.
Stomatal Transpiration
The primary type of transpiration where water evaporates through microscopic pores called stomata present mostly on the underside of leaves.
Potometer
An experimental device used to measure the rate of water intake by a cut shoot, which is nearly equal to the water lost through transpiration.
Guttation
The loss of water in liquid form from the margins of leaves through special structures called hydathodes, usually occurring at night or early morning.
Root Pressure
The hydrostatic pressure developed in the roots due to continuous active absorption of water, helping push water up to small heights in plants.
Important Formulas
Board Exam Info
In ICSE Class 10 Biology, this chapter typically carries around 5 to 8 marks. Questions often include diagram labeling of stomata or potometers, experimental reasoning (e.g., why oil is poured on water in a potometer), and distinguishing between transpiration and guttation.
Frequently Asked Questions
Why is transpiration called a 'necessary evil'?
It causes a dangerous loss of water leading to wilting, but it is necessary because it creates the transpiration pull for upward movement of water and minerals, and cools the plant.
What is the function of oil in a potometer experiment?
A layer of oil is poured on the surface of water in a potometer to prevent loss of water through direct evaporation from the surface.
How does humidity affect the rate of transpiration?
Higher humidity in the surrounding air decreases the rate of transpiration because the diffusion gradient between the leaf air spaces and the atmosphere is reduced.
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