Carbohydrates (WJEC A-level Biology)

This engaging lesson describes the structure, properties and functions of the monosaccharides, disaccharides and polysaccharides. The PowerPoint lesson has been designed to cover point [c] as detailed in AS unit 1, topic 1 of the WJEC A-level Biology specification and it makes clear links to the upcoming lessons in this topic on alpha and beta glucose and the properties of starch, glycogen, cellulose and chitin.

The lesson begins with a made-up round of the quiz show POINTLESS, where students have to try to identify four answers to do with carbohydrates. In doing so, they will learn or recall that these molecules are made from carbon, hydrogen and oxygen, that they are a source of energy which can sometimes be rightly or wrongly associated with obesity and that the names of the three main groups is derived from the Greek word sakkharon. A number of quick quiz rounds have been written into the lesson to introduce key terms in a fun and memorable way and the first round allows the students to meet some of common monosaccharides. Moving forwards, students will learn that a disaccharide is formed when two of these monomers are joined together and they are then challenged on their knowledge of condensation reactions which were originally encountered during the lesson on water. Students will understand how multiple reactions and multiple glycosidic bonds will result in the formation of a polysaccharide and glycogen, starch and cellulose are recalled and there is a brief introduction to chitin. The final part of the lesson considers how hydrolysis reactions allow polysaccharides and disaccharides to be broken back down into monosaccharides.