The importance of water (WJEC A-level Biology)

This detailed lesson describes the properties of water to demonstrate the importance of this molecule for living organisms. The engaging PowerPoint and accompanying resource have been designed to cover the details of specification point (b) of AS unit 1, topic 1 of the WJEC A-level Biology course and has been specifically designed to ensure that each role is illustrated using a specific example.

As this is only the second lesson in the biological compounds topic, which is a topic that students tend to find difficult or potentially less engaging, the planning has centred around the inclusion of a wide variety of tasks to cover the content whilst maintaining motivation and engagement. These tasks include current understanding and prior knowledge checks, discussion points and quick quiz competitions to introduce key terms and values in a memorable way. The start of the lesson considers the structure of water molecules, focusing on the covalent and hydrogen bonds, and the dipole nature of this molecule. Time is taken to emphasise the importance of these bonds and this property for the numerous roles of water and then over the remainder of the lesson, the following properties are described and discussed and linked to real-life examples:

• polarity
• ability to form hydrogen bonds
• surface tension
• as a solvent
• thermal properties
• as a metabolite

The final part of the lesson introduces condensation and hydrolysis reactions and students will learn that a clear understanding of these reactions is critical as they will reappear throughout the topic in the synthesis and breakdown of biological compounds