Question

What features of water explain how it can be drawn up a tall tree from roots to leaves? a. cohesion, the result of extensive hydrogen bonding b. adhesion, water’s tendency to stick to surfaces such as the inner walls of tracheid and vessels c. high surface tension that develops when water evaporates from intercellular leaf spaces d. all of the above e. none of the above

Short answer

The correct answer is d. all of the above.

Step-by-step solution

Understanding the Options

Firstly, analyze each given option - this involves understanding what each term signifies. Cohesion refers to water molecules being attracted to each other, adhesion refers to water molecules being attracted to other substances, surface tension refers to the cohesion between water molecules at the surface of a body of water, and evaporation refers to the process of water changing from a liquid to a gaseous state.

Connecting the Concepts

Secondly, connect these concepts to the mechanics of how water is transported from the roots to the leaves in a tree. Cohesion helps water to form a continuous stream within the xylem (a type of transport tissue) of the plant, while adhesion helps the water stick to the inside walls of the plant's tubes, counteracting the force of gravity. When water evaporates from the leaves, a surface tension is created which pulls more water up through the plant.

Making the Decision

Finally, after having understood and connected all the concepts, it is clear that all the options (cohesion, adhesion, surface tension, evaporation) play a role in the process of water's ascent in a tree. Therefore, the correct option is 'd. all of the above'.

Key concepts

Cohesion in Water

Cohesion in water refers to the attraction that water molecules have for each other. This happens because of the hydrogen bonds that form between them. These bonds make water molecules "stick" together, forming a continuous stream.
In the context of water transport in trees, this cohesion is essential. As water is pulled up through the tree, especially through the xylem, the water molecules stick together, creating a water column.

• This column is important because it allows for the smooth transport of water from the roots to the leaves.
• Without cohesion, the water column could break, interrupting the flow of water.

Thus, cohesion plays a critical role in helping trees transport water efficiently.

Adhesion in Plants

Adhesion describes how water molecules are attracted to other substances. In trees, this involves water sticking to the walls of the xylem vessels and tracheids, which are small tubes within the plant.
This adhesion is crucial as it helps the water fight against gravity.

• By adhering to the walls, the water does not slip back down the tubes.
• This ensures a smoother upward movement of water through the tree.

In combination with cohesion, adhesion ensures that water reaches all parts of the tree effectively.

Surface Tension in Leaves

Surface tension is the result of cohesion at the surface of a liquid. In leaves, this occurs when water evaporates from the surface, generating a pulling force.
This pull is important for drawing more water up through the plant.

• The surface tension at the leaf surface assists in maintaining the water column within the xylem.
• Without this force, the upward transport of water would be less efficient.

Surface tension thus supports the continuous movement of water throughout the tree by creating a persistent upward pull.

Hydrogen Bonding

Hydrogen bonding is a key factor contributing to the properties of water that make it essential for life, including in trees. These bonds occur between the slightly positive hydrogen atoms and the slightly negative oxygen atoms of neighboring water molecules.
The strength of hydrogen bonds gives water its cohesive properties.

• This bonding ensures the formation of the water column in the xylem.
• It provides the stability needed for both cohesion and adhesion to function properly.

Without hydrogen bonding, water would not be able to move effectively through the plant's xylem.

Xylem Transport

Xylem transport refers to the movement of water and nutrients from the roots up through a plant. The xylem is a specialized tissue designed for this purpose.

• It consists of hollow, tube-like structures that create a continuous pathway from roots to leaves.
• The cohesion and adhesion of water within the xylem maintain the stability of the water column.

As water evaporates from the leaves, it causes a decrease in pressure that pulls more water into the xylem system, facilitating its continuous transport upward.