Understanding Transpiration in Plants for Success in O Level Biology

You’ve studied how plants absorb water. But have you ever wondered how they release it? Dive into this article to unravel the secret and ace your O Level Biology course.

What is Transpiration in Plants

It is a process through which plants release water vapour to their surroundings

Students often have the question, “Transpiration in plants occurs through what exactly?

The answer is stomata:

  • Stomata are tiny openings, often found on the underside of leaves

  • They allow water from inside the leaf to escape to the surroundings

  • This “diffusion” of water vapour occurs down the concentration gradient.

If you are not comfortable with the concepts of diffusion and concentration gradient, read our article here for a complete explanation!


Why Should I Know about Transpiration in Plants

If you’re wondering how to get A* in O Level Biology, understanding the meaning of transpiration in plants is a good starting point. It forms the basis of the chapters on plant biology.


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Importance of Transpiration in Plants

A plant doesn’t just release water without reason. In fact, this process serves vital purposes:

  • Release of water helps cool the plant, just like how sweating helps reduce human body temperature

  • It also helps the plant turgid and upright

Factors Affecting Transpiration in Plants

Factors affecting transpiration in plants are:

  • Light: Stomata open wider in bright light, increasing the rate of transpiration.

  • Humidity: High humidity reduces transpiration. If there is already moisture in the outside air, water vapour won’t diffuse out of the stomata as easily.

  • Wind: Faster wind carries away the released water vapour, setting up a steep concentration gradient and increasing transpiration

Tips to Ace Transpiration Questions in O Level Biology

We are often asked: “Is O Level Biology hard?”. Not at all, if you take time building concepts:

  • Memorize the factors that affect the rate of transpiration in plants and understand their explanations.

  • Jot down bullet points on the importance of transpiration in plants


To recap, the meaning of transpiration in plants is “breathing out” water vapour. Transpiration is useful for plants because it aids cooling and helps maintain turgidity.

Remember, being thorough with this chapter can help you score top marks in O Level Biology. If you found this guide useful and want to learn more, stay tuned to Out-Class for more! 

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