Respiratory substrates (CIE A-level biology)

This lesson explains the relative energy values of the respiratory substrates, carbohydrates, lipids and proteins. The PowerPoint and accompanying resources have been planned to cover the content of point 12.1 (4) of the CIE A-level biology specification (for assessment in 2025 - 2027).

The lesson begins with a challenge, where the students have to recognise the key term substrate using either 1 or 2 descriptions. The definition of a respiratory substrate is provided and students will learn that although glucose is the chief respiratory substrate, lipids and proteins can be metabolised to generate molecules of ATP. A quick quiz round is used to introduce the relative energy value per gram of carbohydrate and then this is used as a reference value for the remainder of the lesson. Students will learn that the energy value is higher for lipids and this is explained, making reference to the stages of respiration that will be covered in greater depth in the 12.2 lessons. The final part of the lesson considers proteins and makes a link to deamination, which again will be covered later in the course.

The lesson contains multiple understanding checks and all answers are embedded into the PowerPoint to allow students to assess their progress.