CIE - AS Level Biology - Water - Revision Guide

Cambridge International - AS Level Biology

Resource Type: Revision Guide

Format: Word

Unit: Biomolecules

Topic: Water

Summary:
Hydrogen bonding occurs between water molecules due to the polarity of the water molecule. A water molecule consists of two hydrogen atoms bonded to one oxygen atom. The oxygen atom has a slightly negative charge, while the hydrogen atoms have a slightly positive charge. This polarity allows water molecules to form hydrogen bonds with each other. The oxygen atom of one water molecule attracts the hydrogen atom of another water molecule, creating a weak bond. This attraction between water molecules leads to the unique properties of water.

Water’s solvent action is crucial for living organisms. Its polar nature allows it to dissolve a wide range of substances, such as salts, sugars, and many organic molecules. This property enables water to transport essential nutrients, ions, and waste products within organisms.

Water has a high specific heat capacity, meaning it can absorb and retain a large amount of heat without a significant change in temperature. This property helps regulate temperature in living organisms, preventing sudden fluctuations. It buffers against temperature changes in environments, providing a stable habitat for many organisms.

Water also possesses a high latent heat of vaporization, requiring a significant amount of heat to convert it from a liquid to a gas. This property allows organisms to cool down by evaporative cooling, such as through sweating or panting. It helps maintain temperature homeostasis and prevents overheating in organisms.

Understanding these properties of water provides insights into its vital roles as a solvent, temperature regulator, and coolant in the functioning and survival of living organisms.