Transpiration

Definition

Transpiration is the process by which water vapor is released from the surfaces of plants, particularly through tiny openings called stomata. This movement of water vapor plays a crucial role in the water cycle by contributing to the overall moisture in the atmosphere and facilitating the transport of nutrients within plants. Additionally, transpiration helps regulate plant temperature and influences weather patterns by contributing to cloud formation and precipitation.

5 Must Know Facts For Your Next Test

1. Transpiration occurs mainly during the day when stomata are open for gas exchange, allowing more water to evaporate.
2. About 90% of the water taken up by roots is lost through transpiration, highlighting its importance in plant hydration.
3. Transpiration creates a negative pressure in the plant's xylem, assisting in the upward movement of water and nutrients from roots to leaves.
4. The rate of transpiration can be influenced by environmental factors such as temperature, humidity, wind speed, and light intensity.
5. Transpiration plays a vital role in the water cycle by returning water vapor to the atmosphere, which can later condense and contribute to precipitation.

Review Questions

• How does transpiration contribute to nutrient transport within plants?
  • Transpiration helps create a negative pressure within the plant's xylem, which facilitates the upward movement of water along with dissolved nutrients from the roots to the leaves. As water evaporates from the stomata during transpiration, it pulls more water up from the roots due to cohesion and adhesion properties of water molecules. This process not only helps supply essential nutrients but also maintains hydration in plant tissues.
• Discuss how environmental factors influence the rate of transpiration in plants.
  • Environmental factors such as temperature, humidity, wind speed, and light intensity significantly impact the rate of transpiration. Higher temperatures can increase evaporation rates from leaf surfaces, leading to greater transpiration. Conversely, high humidity levels can reduce transpiration because the concentration gradient between the inside of leaves and the outside air decreases. Wind can enhance transpiration by removing moisture-laden air around the stomata, while increased light intensity typically opens stomata for photosynthesis, also promoting higher transpiration rates.
• Evaluate the significance of transpiration within the broader context of the water cycle and climate regulation.
  • Transpiration is crucial for maintaining moisture levels in the atmosphere and plays an integral role in the water cycle. By releasing water vapor into the air, it contributes to cloud formation and precipitation patterns that impact local climates. Furthermore, it helps regulate temperatures in both plants and their surrounding environments. Understanding how transpiration affects weather systems can provide insights into climate change impacts, as alterations in plant behavior or distribution could disrupt regional hydrology and weather patterns.

Related terms

Stomata: Small openings on the surface of leaves that allow for gas exchange and transpiration to occur.

Evaporation: The process by which liquid water is transformed into water vapor, contributing to moisture in the atmosphere.

Photosynthesis:

The process by which green plants use sunlight to synthesize foods from carbon dioxide and water, while releasing oxygen as a byproduct.