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Delivery guides are designed to represent a body of knowledge about teaching a particular topic and contain:
- Content: A clear outline of the content covered by the delivery guide;
- Thinking Conceptually: Expert guidance on the key concepts involved, common difficulties students may have, approaches to teaching that can help students understand these concepts and how this topic links conceptually to other areas of the subject;
- Thinking Contextually: A range of suggested teaching activities using a variety of themes so that different activities can be selected which best suit particular classes, learning styles or teaching approaches.
Having identified and understood the roles of DNA and enzymes in Section B1.2, learners will investigate two important cellular reactions that provide cells with the resources necessary to maintain life.
B1.3a describe cellular respiration as a universal chemical process, continuously occurring in all living cells that supplies ATP
B1.3b describe cellular respiration as an exothermic reaction including:
B1.3c compare the processes of aerobic and anaerobic respiration
– in plants/fungi and animals the different conditions, substrates, products and relative yields of ATP
B1.3d explain the importance of sugars in the synthesis and breakdown of carbohydrates including:
– use of the terms monomer and polymer
B1.3e explain the importance of amino acids in the synthesis and breakdown of proteins including:
– use of the terms monomer and polymer
B1.3f explain the importance of fatty acids and glycerol in the synthesis and breakdown of lipids
Metabolic processes such as respiration are controlled by enzymes. Organic compounds are used as fuels in cellular respiration to allow the other chemical reactions necessary for life.
Underlying knowledge and understanding
Learners should also have some underpinning knowledge of respiration. This should include that respiration involves the breakdown of organic molecules to enable all the other chemical processes necessary for life. Learners should be able to recall the word equation for respiration.
Common misconceptions or difficulties students may have
Learners commonly hold the misconception that ventilation is respiration. They can also get confused between the terms breakup and breakdown. The word and symbol equation for aerobic respiration is also easily mixed up with that of photosynthesis covered in Section B1.4. This is understandable as it is the reverse, however, care must be taken to avoid this common difficulty.
Conceptual links to other areas of the specification - useful ways to approach this topic to set students up for topics later in the course
Respiration is a ubiquitous reaction found in living organisms. It is specifically covered in the topic ‘Ecosystems’ where it is considered in terms of decomposition.
In the topic ‘Maintaining Internal Environments’ respiration is seen as a key factor involved in maintaining a constant internal environment. There will be many other areas where an understanding of respiration will underpin the reasons for other biological processes.
Approaches to teaching the content
Continuing with the experimental nature of the topic as a whole, this section again provides a wide range of practical activities, both real and virtual. It is crucial that learners are provided with practical opportunities to develop appropriate skills but importantly this will encourage a deeper understanding of the complex aspects of the cellular reactions that are to be studied. 'Demonstrating an exothermic reaction' introduces the idea of exothermic reactions set in a real-life context that learners will be familiar with.
Commercial heat packs can be used to a show exothermic reaction.
To conduct a very quick demonstration as a starter activity:
- Set off heat packs and pass them around the learners.
Note: be sure to get the heat packs back! They are reusable! Heat packs are saturated sodium acetate solutions. Flexing the metal disc inside provides a crystallization site, and the solution crystallizes within seconds. The crystallization is a strongly exothermic process. This can be used as a discussion point to raise a Q&A session on where the heat is generated in our bodies (cellular respiration).
For the curious, a video explanation of how the heat pack works can be found in the resources link.
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