Water Review A.1.1.3

Front

What is the scientific term for the property of water molecules sticking together?

Back

Cohesion

Front

What role does cohesion play in plants?

Back

Cohesion allows the transport of water under tension in plants, enabling water to be sucked upwards from the roots to the leaves along tubular vessels in xylem tissue.

Front

How is tension generated in the roots and leaves of plants?

Back

Tension in the roots is generated by attractions between soil particles and water, while tension in the leaves develops as water is lost by evaporation to the atmosphere and due to attractions between water molecules and the cell walls of leaf cells.

Front

Why can water in xylem withstand tensions?

Back

Water in xylem can withstand tensions because hydrogen bonds make it cohesive, allowing it to be pulled upwards as long as the water column remains continuous.

Front

What would happen if there were fewer hydrogen bonds in water columns in xylem?

Back

If there were fewer hydrogen bonds, columns of water in xylem would break more easily, and trees would not be able to grow so tall.

Front

What is surface tension and why does it occur in water?

Back

Surface tension is the effect where the surface of a body of water acts like an elastic membrane. It occurs because water molecules are more attracted to each other by hydrogen bonding than to air particles.

Front

How do living organisms use the surface tension of water?

Back

Living organisms use the surface tension of water as a habitat. For example, water striders walk on the water surface, and mosquito larvae hang just below the surface using their siphon.

Front

Why can objects like steel pins float on water despite being denser?

Back

Objects like steel pins can float on water because the cohesion between water molecules due to hydrogen bonds is greater than the attractions between water and the floating object.