2.4 Water and its functions

Question 1

Water is a dipolar molecule.
•What is a dipolar molecule?

Answer 1

A molecule that has no overall charge, slightly negative charge a and slightly positive charge

Question 2

Water is a universal solvent.
What does water dissolve?

Answer 2

• gases such as oxygen and CO2
• wastes such as ammonia + urea
• inorganic ions and small hydrophilic molecules such as amino acids, ATP
• enzymes

Question 3

Water has properties of adhesion and cohesion.
Define adhesion and Cohesion.

Answer 3

A - attraction between molecules of different substances

C - attraction between molecules of the same substance

Question 4

Water is less dense as a solid than a liquid.
How is this beneficial to living organisms?

Answer 4

Only surface of water is frozen so water underneath allows for organisms to still survive, ice doesn’t sink and kill them too.

Question 5

Water is important for capillary action.
How does this work?

Answer 5

Cohesion between the water molecules, with hydrogen bonding water has large cohesive forces and allows it to be pulled up through a tube, such as a XYLEM VESSEL.

Question 6

Water has a high heat of vaporisation.
Why?

Answer 6

As water molecules stick to one another, energy is needed to break the bonds. A high amount of energy is needed to break the bonds.

Question 7

Water has a high surface tension.
Explain why?

Answer 7

The cohesive property allows for hydrogen bonds between the water molecules to ‘stick’ to one another which creates a film over the surface.