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transpiration

Primary Information
Secondary Information

Definition

Transpiration is the process of water vapour diffusion from the aerial parts of plants into the atmosphere. It is a major component of the water cycle.

Transpiration is driven by the difference in water vapour pressure between the inside of the leaf and the outside air. The inside of the leaf is humid because of the evaporation of water from the mesophyll cells. The outside air is less humid because of the water vapour that has already evaporated from other plants and the ground.

Transpiration is important for plants because it helps to cool them down and to transport water and nutrients throughout the plant. It also helps to regulate the atmosphere by transferring water vapour into the air.

The rate of transpiration is affected by a number of factors, including:

  • The amount of water available to the plant
  • The temperature of the air
  • The humidity of the air
  • The wind speed
  • The amount of sunlight
  • The type of plant

How can the word be used?

Transpiration is an important process for plants, as it helps them to cool down and to get rid of excess water.

transpiration

Different forms of the word

Noun:

the process by which water vapour is released from the leaves of plants into the atmosphere.

Verb:

to release water vapour from the leaves of plants into the atmosphere.

Etymology

The word "transpiration" comes from the Latin words "trans" and "spirare", which mean "through" and "breathe" respectively.

The first recorded use of the word "transpiration" in English was in the 17th century.

The word "transpiration" is a Latin word, and it is related to the Italian word "traspirazione" and the Spanish word "transpiración".

Question

What is transpiration?

AQA Science Exam Question and Answer

Question:

Explain the process of transpiration in plants and its role in the overall functioning of a plant's vascular system. Describe how factors such as temperature, humidity, and wind affect the rate of transpiration. Provide an example of how plants benefit from transpiration.

Answer:

Transpiration is the process through which plants lose water vapour from their leaves into the atmosphere. It plays a crucial role in a plant's overall functioning, particularly in the transport of water and nutrients through the vascular system.

During transpiration, water is drawn up from the roots through the xylem vessels and transported to the leaves. Once in the leaves, water molecules evaporate from tiny pores called stomata, located mainly on the underside of leaves. This process creates a negative pressure that facilitates the upward movement of water, allowing nutrients to be transported along with it.

Several environmental factors influence the rate of transpiration. Higher temperatures increase the rate of water evaporation, as warmer air can hold more moisture. Humidity affects the concentration gradient between leaf and air, influencing water vapour movement. Wind increases transpiration by carrying away the water vapour and maintaining a drier environment around leaves.

Plants benefit from transpiration in various ways. It helps to cool the plant by releasing excess heat through water vapour, similar to how sweating cools our bodies. Additionally, transpiration creates a suction force that helps draw water and nutrients from the soil into the roots. This process supports photosynthesis, nutrient transport, and structural stability in plants.