Scheme of Work Cambridge International as & a level

Extension activity: Learners explain how alternative experiments, without the use of respirometers, can be conducted to give more accurate readings for values of the respiratory quotient.

12.2 Respiration KC1 KC2 KC6

12.2.1 State where each of the four stages in aerobic respiration occurs in eukaryotic cells. 12.2.2 Outline glycolysis as phosphorylation of glucose and the subsequent splitting of fructose 1,6-bisphosphate (6C) into two triose phosphate molecules (3C), which are then further oxidised to pyruvate (3C), with the production of ATP and reduced NAD. 12.2.3 Explain that, when oxygen is available, pyruvate enters mitochondria to take part in the link reaction. 12.2.4 Describe the link reaction, including the role of coenzyme A in the transfer of acetyl (2C) groups . 12.2.5 Outline the Krebs cycle. 12.2.6 Explain that reactions in the Krebs cycle involve decarboxylation and dehydrogenation and the reduction of the coenzymes NAD and FAD. 12.2.7 Describe the role of NAD and FAD in transferring hydrogen to carriers in the inner mitochondrial membrane. 12.2.8 Explain what happens during oxidative phosphorylation. 12.2.9 Describe the relationship between the structure and function of mitochondria using diagrams and electron micrographs.

Remind learners of the molecular structure of glucose from Topic 2 by showing a model of this molecule. Elicit discussion to explain that the atoms can be separated, and this underlies the process of respiration. (F) Help learners to understand that dividing a complex biological mechanism into smaller stages can help to understand it. After describing the mechanisms, learners close their books and attempt to sketch or record as bullet points the key facts on a blank piece of paper. Next, allow leaners to look at their notes and correct and classify their own errors to reflect on their performance. Animations and interactive graphics: www.science.smith.edu/departments/Biology/Bio231/etc.html, www.sumanasinc.com/webcontent/animations/content/cellularrespiration.html, http://highered.mheducation.com/sites/9834092339/student_view0/chapter7/how_glycolysis_works.html, www.wiley.com/legacy/college/boyer/0470003790/animations/tca/tca.htm, http://vcell.ndsu.nodak.edu/animations/flythrough/mitochondria_03.htm www.johnkyrk.com (F) Learners work in pairs to draw and label a diagram of a mitochondrion on a piece of poster paper. Review misconceptions as you walk around the room, and then produce a diagram on the board for learners to use to make their corrections. Extend the activity by asking learners to write the name of each of the four stages of aerobic respiration in the correct locations on the mitochondrion. You can use resources to illustrate the events of aerobic respiration, such as the poster at: https://bigpictureeducation.com/cellular-respiration-poster Set up a Krebs cycle ‘circus’ for learners to move between stations at which they collect or drop off coins or photocopies of molecular structures that represent the different intermediates. Learners design two or three multiple-choice questions on the subject of aerobic respiration. Before the next lesson, select the best 10 and provide these to the class as a formative exercise. This will motivate learners to make high-quality questions. (F)