This detailed lesson describes the relationship between the structure and function of starch and cellulose. The engaging PowerPoint and accompanying resource have been designed to cover point 4.9 of the Pearson Edexcel A-level Biology A specification and focuses on the importance of the glycosidic and hydrogen bonds for the structure of these polysaccharides.
The structure of amylose and amylopectin was described during a lesson in topic 1, so the start of this lesson challenges the students on their recall of these details. They have to complete a comparison table for these two polysaccharides by identifying the monomer and type of glycosidic bonds that are found in each of the structures. Time is taken to explain how the greater resistance to digestion of amylose means that this carbohydrate is important for plant energy storage whereas the multiple chain ends in the branched amylopectin means that this polysaccharide can be hydrolysed quickly when energy is needed. The rest of the lesson describes the structure of cellulose and focuses on the link between the structure and the need for this polysaccharide to support the plant cell as well as the whole plant. Students will see how every other beta glucose monomer is rotated by 180 degrees and will learn that hydrogen bonds form between these molecules on the same chain as well as between adjacent chains in a cellulose microfibril.
The lesson concludes with a quick quiz competition where the students have to compete to open a safe using a combination made up of key values associated with glycogen, starch and cellulose.
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Topic 4: Biodiversity and natural resources (Edexcel SNAB)
This lesson bundle contains 11 lesson PowerPoints and their accompanying resources which are filled with a wide variety of tasks to motivate and engage the students whilst covering the detailed content of topic 4 of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification. Extensive planning has gone into each lesson to ensure that understanding is complete and that students are challenged to make links to previously covered topics. The tasks include exam-style questions, differentiated tasks, guided discussion points and quick quiz competitions and together these cover the following specification points in topic 4: * The meaning of the terms biodiversity and endemism * Measuring biodiversity within a habitat using species richness and within a species by calculating the heterozygosity index * Comparing biodiversity between habitats by calculating an index of diversity * The concept of niche and examples of behavioural, anatomical and physiological adaptations * Natural selection can lead to adaptation and evolution * The Hardy-Weinberg equation can be used to see whether a change in allele frequency is occurring in a population over time * Reproductive isolation can lead to the formation of new species * Classification is built around the species concept * Critical evaluation of new data by the scientific community, which leads to new taxonomic groupings * The ultrastructure of plant cells * The structure and function of the polysaccharides starch and cellulose * The similarities and differences between the structures, position and function of sclerenchyma fibres, xylem vessels and phloem * The importance of water and inorganic ions to plants * Evaluate the methods used by zoos and seed banks in the conservation of endangered species and their genetic diversity If you would like to sample the quality of the lessons in this bundle, then download the isolation and speciation, ultrastructure of plant cells and xylem, phloem and sclerenchyma lessons as these have been uploaded for free
Biological molecules (Edexcel SNAB)
This lesson bundle contains 10 lessons which have been designed to cover the Pearson Edexcel A-level Biology A (Salters Nuffield) specification points which focus on the structure and function of the biological molecules, including water, carbohydrates, lipids and proteins. The lesson PowerPoints are highly detailed, and along with their accompanying worksheets, they have been planned at length to contain a wide range of engaging tasks which cover the following A-level Biology content that's found in topics 1, 2 and 4 of the course: 1.2: Understand the importance of water as a solvent in transport, including its dipole nature 1.12 (i): Know the difference between monosaccharides, disaccharides and polysaccharides, including glycogen and starch (amylose and amylopectin) 1.12 (ii): Be able to relate the structures of monosaccharides, disaccharides and polysaccharides to their roles in providing and storing energy 1.13: Know how monosaccharides join to form disaccharides (sucrose, lactose and maltose) and polysaccharides (glycogen and amylose) through condensation reactions forming glycosidic bonds, and how these can be split through hydrolysis reactions 1.14 (i): Know how a triglyceride is synthesised by the formation of ester bonds during condensation reactions between glycerol and three fatty acids. 1.14 (ii): Know the differences between saturated and unsaturated lipids 2.9 (i): Know the basic structure of an amino acid 2.9 (ii): Understand the formation of polypeptides and proteins (amino acid monomers linked by peptide bonds in condensation reactions) 2.9 (iii): Understand the significance of a protein’s primary structure in determining its three-dimensional structure and properties (globular and fibrous proteins and the types of bonds involved in its three-dimensional structure) 2.10 (iv): Know the molecular structure of a globular protein and a fibrous protein and understand how their structures relate to their functions (including haemoglobin and collagen) 4.9: Understand the structure and function of the polysaccharides starch and cellulose, including the role of hydrogen bonds between β-glucose molecules in the formation of cellulose microfibrils
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