The phenomenon responsible for maintaining the upward movement of water through vessels in a tree is __________.

• A. hydration shells
• B. surface tension
• C. specific heat
• D. cohesion

Answer: (D)

Verified step by step guidance

1. Understand the concept of cohesion: Cohesion refers to the attraction between molecules of the same substance. In the context of water movement in plants, it is the force that holds water molecules together.
2. Recognize the role of cohesion in plants: In trees, cohesion helps maintain a continuous column of water within the xylem vessels, which are the tubes that transport water from the roots to the leaves.
3. Identify the process of transpiration: Transpiration is the process by which water evaporates from the leaves, creating a negative pressure that pulls water upward through the plant.
4. Connect cohesion to transpiration: As water molecules evaporate from the leaf surface, they pull on the water molecules behind them due to cohesion, facilitating the upward movement of water.
5. Differentiate from other terms: Hydration shells and specific heat are unrelated to the upward movement of water in plants. Hydration shells refer to water molecules surrounding ions, and specific heat is the amount of heat required to change the temperature of a substance.