Cohesion

When hydrogen bonds are able to hold a substance together, this is called cohesion. A good example of this is liquid water. When the bonds break, they quickly form and re-form. They last extremly short but the hydrogen bonds are able to make this process of breaking,forming and reforming very quickly so that the water sticks together. Therefore, water molecules are able to bond to their neighbors, making water more structured than most liquids. This is pictured below in the photo with the water molecules staying together due to cohesion.

Cohesion also plays a big part when it comes to transporting water against gravity in plants. When water enters the roots, it moved upward through microscopic vessels to the leaves. The water in these vessels in the veins of the left replace the water that evaporates from the leaft. Water molecules leaving the veins tug molecules farther down in the vessel because of hydrogen bonding. Because of this, the upward pull is transmitted along the vessel down to the roots. Adhesion also plays a role.


Works Cited:
Campbell, Neil, Jane Reece, and Lawrence Mitchell. “Water and the Fitness of the Environment.” Biology. Fifth ed. Menlo Park: Jim Green Publishing, 1999. 38. Print.