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Weekly plan 9 Respiration 3 Student book links Specification links 1.4.8 1.4.9 4.4.1 (t)–(w) Link to GCSE/AS specification Suggested time allowed (includes contact and non-contact time): GCSE Respiration Nutrition and diet 3 hours AS 1.1.1 Cell structure 1.1.2 Cell membranes 2.1.1 Biological molecules 2.1.2 Nucleic acids 2.1.3 Enzymes Suggested teaching order Weekly learning outcomes Student should be able to: Explain why anaerobic respiration produces a much lower yield of ATP than aerobic respiration. Compare and contrast anaerobic respiration in mammals and in yeast. Define the term: respiratory substrate. Explain the difference in relative energy values of carbohydrate, lipid and protein respiratory substrates. Key words Anaerobic respiration Relative energy value 1. 2. 3. 4. 5. 6. Glycolysis as a common factor to aerobic and anaerobic respiration Effect of lack of oxygen Lactate fermentation Alcoholic fermentation Define the term: respiratory substrate Energy values of different substrates How Science Works Respiratory substrate Lactate fermentation Aerobic respiration Alcoholic fermentation HSW 5 Investigate the effect of a variable on the rate of respiration or compare aerobic and anaerobic respiration in yeast. Calculate rates of respiration; plot graphs showing the effect of a variable on respiration; and identify and evaluate the limitations of measuring respiration rate. Learning styles (S = Starter activities, M = Main activities, P = Plenary activities) ICT activities Kinaesthetic Activities S1–3 Activities M1–7 Activities P2–3 Interpersonal Activities S1–3 Activities M1–7 Activities P1–3 Auditory Activities S1–3 Activities M1–7 Activities P1–3 Visual Activities S1–3 Activities M1–7 Activities P1–3 See Activity S2 below – writing risk assessments using a word processor and collating ideas via an IWB. See Activity S3 below – use of a spreadsheet to help with calculations. See Activities M1–7 below – writing investigations using a word processor and processing data using a spreadsheet. The web links referred to here are some that the author has found personally helpful but are not intended to be a comprehensive list, many other good resources exist. © Pearson Education Ltd 2009 This document may have been altered from the original 1 Weekly plan 9 Suggested starter activities Equipment Teacher notes 1. Introduce each practical investigation and its aims to the class. 2. As a class, conduct a risk assessment for each Practical activity in the Main activities below. 3. In groups, students use nutritional data from cereal packets to calculate energy values from different food groups. Cereal packets Suggested main activities Equipment Teacher notes 1. Practical activity 10: Determining the respiration rate using respirometers See technician worksheet. See teacher worksheet. 2. Practical activity 11: Determining the respiratory quotient (RQ) of germinating seeds See technician worksheet. See teacher worksheet. 3. Practical activity 12: Investigating dehydrogenase activity in anaerobic respiration of yeast See technician worksheet. See teacher worksheet. 4. Practical activity 13: To investigate the effect of the type of substrate on yeast respiration See technician worksheet. See teacher worksheet. 5. Practical activity 14: The effect of temperature on yeast respiration See technician worksheet. See teacher worksheet. 6. Practical activity 15: The effect of ethanol on yeast respiration See technician worksheet. See teacher worksheet. 7. Practical activity 16: Comparing anaerobic and aerobic respiration See technician worksheet. See teacher worksheet. Suggested plenary activities Equipment Teacher notes 1. Collate practical results and conclusions from the Practical activities as a class. 2. Each student has to stand up and say one thing they have learned from this topic. 3. In groups, students draw a concept map showing how yeast respiration is affected by the variables investigated in the Main activities above. Any other student who has learned the same thing must also stand up – all those standing need to swap places. A3 paper © Pearson Education Ltd 2009 This document may have been altered from the original 2 Weekly plan 9 Homework suggestions Compare and contrast anaerobic respiration in mammals and in yeast. Research a booklet which examines the industrial applications of anaerobic respiration. Complete the write-up of all the Practical activities. Cross-curriculum links Physics – forms of energy Chemistry – redox, mole calculations Physical education – aerobic and anaerobic respiration Home economics – alcohol and bread production PSHE – diet Stretch and Challenge The links to the AS specification stated on page 1 are a good opportunity to develop Stretch and Challenge skills. Pasteur observed that yeast consumes far more glucose when growing under anaerobic conditions than when growing under aerobic conditions. Scientists now know that the rate of ATP production by anaerobic glycolysis can be up to 100 times faster than that of oxidative phosphorylation, but much glucose is consumed and the end product, ethanol, still has a lot of potential chemical energy. When mammalian muscle tissues are rapidly using ATP, they can regenerate it almost entirely by anaerobic glycolysis and lactate fermentation. A great deal of glucose is used but this process is not as wasteful as ethanol fermentation – suggest why. Palmitic acid produces eight 2-carbon fragments. This requires seven turns of the -oxidation cycle. For each turn of the -oxidation cycle, one reduced NAD and one reduced FAD are produced. The seven FAD and seven NAD are reoxidised via oxidative phosphorylation, the hydrogen from reduced NAD being involved in chemiosmosis and ATP synthesis. Each acetyl group enters the Krebs cycle and produces one reduced FAD and three reduced NAD, as well as one ATP by substrate-level phosphorylation. Eight turns of the Krebs cycle are needed to deal with the eight fragments produced during -oxidation. The energy equivalent to the hydrolysis of two ATP molecules is used to combine the fatty acid with acetyl CoA. Calculate the net gain of ATP for one molecule of palmitic acid, oxidised via oxidation and the Krebs cycle. Potential misconceptions Students can find the concept of energy difficult to understand. Some students may still think that respiration equates to breathing. Some students think ATP is a form of energy rather than a storage molecule. It is important to clarify the nature of reduction and oxidation reactions early on, as these can be confusing at GCSE. When you present an overview to the students, it is worth doing so against a diagram of the cell – they can link the stages to the different locations early on. Students often confuse NAD with NADP, and NAD with FAD, and these can also appear in diagrams with H added, e.g. NADH! – refer to oxidised NAD or reduced NAD as appropriate. Only present the level of detail given in the textbook – although many other textbooks will give much more detail, it is more important for students to pick up the main ideas rather than the detail of every compound produced. © Pearson Education Ltd 2009 This document may have been altered from the original 3 Weekly plan 9 Spend some time on terminology such as: decarboxylated; dehydrogenated; dehydrogenase; decarboxylase; and phosphorylation. It is worth reinforcing the relationship between proton concentration and pH. Distinguish between the structure and composition of ethanal and ethanol. Notes The web links referred to here are some that the author has found personally helpful but are not intended to be a comprehensive list, many other good resources exist. © Pearson Education Ltd 2009 This document may have been altered from the original 4