Cohesion

Definition

Cohesion refers to the attraction between molecules of the same substance, which in the case of water, is primarily due to hydrogen bonding. This unique property of water enables it to maintain a continuous flow and supports various ecological and biological processes. The cohesive nature of water molecules contributes to surface tension and allows for phenomena such as water droplets forming on surfaces and the movement of water through plant tissues.

5 Must Know Facts For Your Next Test

1. Cohesion is responsible for water's high surface tension, which allows small objects, like insects, to rest on the surface without sinking.
2. Water molecules exhibit cohesion due to hydrogen bonds, creating a strong attraction that can lead to the formation of droplets.
3. This cohesive property plays a critical role in the process of transpiration in plants, helping to transport water from roots to leaves.
4. Cohesion allows water to resist external forces, maintaining its structure and enabling it to form streams and rivers as it flows.
5. In addition to supporting life processes, cohesion affects weather patterns and influences how rain falls and interacts with the environment.

Review Questions

• How does cohesion contribute to the unique properties of water that are essential for life?
  • Cohesion enhances water's unique properties by allowing it to maintain a high surface tension, which is crucial for various biological processes. For example, this property enables small organisms to walk on water surfaces and helps plants transport water through transpiration. Without cohesion, these vital interactions within ecosystems would be disrupted, highlighting its importance for sustaining life.
• Discuss how the concepts of cohesion and adhesion work together in biological systems, particularly in plant transportation.
  • Cohesion and adhesion work hand in hand in biological systems, especially during water transport in plants. While cohesion allows water molecules to stick together, forming a continuous column within xylem vessels, adhesion helps water molecules cling to the walls of those vessels. This combination creates an effective system for moving water from roots to leaves, demonstrating how these two properties are interconnected in supporting plant life.
• Evaluate the environmental implications of water's cohesive properties on ecosystems, particularly regarding habitat stability and nutrient transport.
  • Water's cohesive properties have significant environmental implications for ecosystems, influencing habitat stability and nutrient transport. Cohesion contributes to surface tension, allowing organisms that depend on this feature for survival to thrive in aquatic environments. Additionally, the ability of water to form droplets and move through soil ensures that nutrients are efficiently transported through ecosystems. This interplay highlights how cohesion not only supports individual species but also plays a vital role in maintaining healthy ecosystems.

Related terms

Hydrogen Bonding:

A weak bond that occurs when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom.

Surface Tension:

The elastic-like force existing at the surface of a liquid, caused by the attraction of molecules in the liquid that makes it behave as if covered by an elastic membrane.

Adhesion:

The attraction between different substances, such as water molecules and other materials, which can result in phenomena like capillary action.