Module 2 - Biological molecules - Exam Q's

Question 1

Explain why water is a good solvent.

Answer 1

• Molecules are polar.
• Polarity enables water molecules to bind to solute molecules.

Question 1

Explain five properties that make water important for organisms. (5)

Answer 1

It is a solvent - can take part in many important metabolic reactions.

It is a metabolite - in condensation and hydrolysis reactions

High latent heat of vaporization - produces a sig cooling effect.

High specific heat capacity - buffers temperatures, and does not fluctuate, so produces a stable environment for organisms overall and for enzymic activity.

Cohesion - enables the transport of water through columns transpiration stream + enables surface tension so small predators can live on top of the water. This is achieved through capillary action and adhesion.

Question 2

Explain how properties relating to density of water contribute to the survival of organisms. (3)

Answer 2

• ice is less dense than water so it floats on top.
• floating ice insulates organisms below so they can move.
• water is similar density to organisms so they can float

Question 3

Properties of water that make it ideal for amphibians to live

Answer 3

• It has a high specific heat capacity so is temperature stable.