Water Flashcards – AQA A-Level Biology - (7402)

How does water’s polarity make it a solvent in cells?

Its polar molecules interact with many charged or polar substances, allowing them to dissolve and form aqueous solutions.

Why is water a useful medium for metabolic reactions?

Dissolved substances can move and interact in it, allowing reactions to occur in solution.

What does it mean that water has a relatively high heat capacity?

A substantial amount of energy is needed to raise the temperature of a given amount of water.

What contributes to water’s high heat capacity?

Hydrogen bonding between water molecules.

How does water’s high heat capacity affect temperature changes in biological systems?

Water changes temperature relatively slowly as it gains or loses energy, buffering temperature changes.

What does it mean that water has a relatively high latent heat of vaporisation?

A relatively large amount of energy is needed to vaporise a given mass of water.

Why is energy needed to vaporise water?

To overcome intermolecular attractions, including hydrogen bonds.

How does water evaporating from a surface cool it?

The evaporating water takes energy from the surface.

What does water's high latent heat of vaporisation mean for water loss during evaporative cooling?

Cooling can occur with relatively little loss of water.

What causes cohesion between water molecules?

Attraction between water molecules through hydrogen bonds.

What role does cohesion play in water transport in plants?

It helps maintain continuous columns of water in tube-like transport cells.

What is surface tension at a water–air surface?

Attraction between water molecules makes the surface resist being stretched or broken.