This fully-resourced lesson describes the meaning of the terms stem cell, pluripotency and totipotency. The PowerPoint and accompanying worksheets have been designed to cover points 3.11 (i) and (ii) of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification and therefore this lesson also contains discussion periods where the topic is the decisions that the scientific community have to make about the use of stem cells in medical therapies. The lesson begins with a knowledge recall of the structure of eukaryotic cells and the students have to use the first letters of each of the four answers to reveal the key term, stem cell. Time is then taken to consider the meaning of cellular differentiation, and this leads into the key idea that not all stem cells are equal when it comes to the number of cell types that they have the potential to differentiate into. A quick quiz round introduces the five degrees of potency, and then the students are challenged to use their understanding of terminology to place totipotency, pluripotency, multipotency, oligopotency and unipotency in the correct places on the potency continuum. Although the latter three do not have to be specifically known based on the content of specification point 3.11 (i), an understanding of their meaning was deemed helpful when planning the lesson as it should assist with the retention of knowledge about totipotency and pluripotency. These two highest degrees of potency are the main focus of the lesson, and key details are emphasised such as the ability of totipotent cells to differentiate into any extra-embroyonic cell, which the pluripotent cells are unable to do. The morula, and inner cell mass and trophoblast of the blastocyst are used to demonstrate these differences in potency. The final part of the lesson discusses the decisions that the scientific community have to make about the use of embryonic stem cells, adult stem cells and also foetal stem cells which allows for a link to chorionic villus sampling from topic 2. There is also a Maths in a Biology context question included in the lesson (when introducing the morula) to ensure that students continue to be prepared for the numerous calculations that they will have to tackle in the terminal exams. This resource has been differentiated two ways to allow students of differing abilities to access the work

This lesson describes the uses and implications of pre-implantation genetic diagnosis, amniocentesis and chorionic villus sampling. The lesson PowerPoint and accompanying worksheets have been primarily designed to cover point 2.15 of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification but regular links are made to the earlier content of topics 1 & 2, and their knowledge of topics including the heart and circulation, monohybrid inheritance and cystic fibrosis are tested. The lesson begins by challenging them to use this prior knowledge of topic 2 to identify the letters in the abbreviations PGD and CVS. The involvement of IVF to obtain the embryos (or oocytes) is then discussed and a series of exam-style questions are used to get them to understand how this method screens embryos prior to implantation, so that those identified as having genetic diseases or being carriers are not inserted into the female’s uterus. Mark schemes for all of the questions included in this lesson are embedded into the PowerPoint so students can constantly assess their progress. Moving forwards, Down syndrome (trisomy 21) is used as an example of a chromosomal abnormality that can be tested for using CVS or amniocentesis. Time is taken to describe the key details of both of these procedures so students have a clear understanding of the implications and the invasiveness to the female being tested. The link between amniocentesis and an increased risk of miscarriage is considered and the results of a 2006 study are used to challenge them on their data skills.

This lesson describes the uses and implications of pre-implantation genetic diagnosis, amniocentesis and chorionic villus sampling. The lesson PowerPoint and accompanying worksheets have been primarily designed to cover point 2.17 of the Edexcel International A-level Biology specification but there are regular checks of their knowledge of the content of topic 2, where topics including monohybrid inheritance and cystic fibrosis are tested. The lesson begins by challenging them to use this prior knowledge of topic 2 to identify the letters in the abbreviations PGD and CVS. The involvement of IVF to obtain the embryos (or oocytes) is then discussed and a series of exam-style questions are used to get them to understand how this method screens embryos prior to implantation, so that those identified as having genetic diseases or being carriers are not inserted into the female’s uterus. Mark schemes for all of the questions included in this lesson are embedded into the PowerPoint so students can constantly assess their progress. Moving forwards, Down syndrome (trisomy 21) is used as an example of a chromosomal abnormality that can be tested for using CVS or amniocentesis. Time is taken to describe the key details of both of these procedures so students have a clear understanding of the implications and the invasiveness to the female being tested. The link between amniocentesis and an increased risk of miscarriage is considered and the results of a 2006 study are used to challenge them on their data skills.

This lesson describes the structure and functions of the organelles that are found in eukaryotic cells. The engaging and detailed PowerPoint and accompanying resources have been designed to cover point (a) in AS Unit 1, topic 2 of the WJEC A-level Biology specification As cells are the building blocks of living organisms, it makes sense that they would be heavily involved in all 6 modules in the OCR course and intricate planning has ensured that links to the lessons earlier in AS unit 1 are made as well as to the upcoming topics in the other units. The lesson uses a wide range of activities, that include exam-style questions, class discussion points and quick quiz competitions, to maintain motivation and engagement whilst describing the relationship between the structure and function of the following organelles: nucleus nucleolus centrioles ribosomes rough endoplasmic reticulum Golgi body lysosomes smooth endoplasmic reticulum mitochondria cell surface membrane vacuole chloroplasts plasmodesmata All of the worksheets have been differentiated to support students of differing abilities whilst maintaining challenge Due to the detail that is included in this lesson, it is estimated that it will take in excess of 3 hours of allocated A-level teaching time to go through all of the tasks

This engaging lesson describes the structures of virus particles and explains why viruses are described as acellular and non-living. The PowerPoint and accompanying resource are part of the second lesson in a series of 2 lessons which have been designed to cover the detail of specification point (b) in AS unit 1, topic 2 of the WJEC A-level Biology specification Details of the COVID-19 epidemic are included in the lesson to increase relevance and to help students to understand this biological topic in greater depth. They will understand that the lack of cell structures results in an acellular classification and the fact that it is unable to reproduce without a host is one of the additional reasons that renders it as non-living. The main focus of the lesson is the nucleic acid, the capsid and the attachment proteins that are present in these microorganisms and time is taken to explain how these structures are involved in the infection of a host cell. The lipid membrane is also introduced and links are made to the previous lessons on eukaryotic cells. The final section uses a version of BBC 1’s POINTLESS to introduce a number of viral diseases in animals and the use of a glycoprotein by HIV to attach to helper T cells is briefly introduced so students are prepared for the immunology option if taken

This lesson describes the structure of a prokaryotic cell including the nucleoid, plasmid, 70S ribosomes and cell wall. The engaging PowerPoint and accompanying resources are part of the first lesson in a series of 2 lessons which have been designed to cover the details in specification point (b) in AS unit 1, topic 2 of the WJEC A-level Biology specification. This lesson has been specifically designed to be taught after the lesson on the structure of eukaryotic cells, specification point (a), so that comparisons can be drawn. A clear understanding of terminology is important for A-level Biology so this lesson begins with a challenge, where the students have to come up with a 3-letter prefix that they believe will translate as before or in front of . This leads into the discovery of the meaning of prokaryote as before nucleus which acts to remind students that these types of cell lack this cell structure. Links to the previous lessons on the eukaryotic cells are made throughout the lesson and at this particular point, the students are asked to work out why the DNA would be described as naked and to state where it will be found in the cell. Moving forwards, the students will discover that these cells also lack membrane bound organelles and a quick quiz competition challenges them to identify the specific structure that is absent from just a single word. In addition to the naked DNA, students will learn that there are also ribosomes in the cytoplasm and will discover that these are smaller than those found in the cytoplasm of an eukaryotic cell (but the same size as those in chloroplasts and mitochondria). The remainder of the lesson focuses on the composition of the cell wall, the additional features of prokaryotic cells such as plasmids and there is also the introduction of binary fission as the mechanism by which these organisms reproduce so that students can recognise that prokaryotic cells do not contain centrioles

This lesson describes the levels of organisation, including the aggregation of cells into tissues, tissues into organs and organs into organ systems. The detailed and engaging PowerPoint and accompanying resources have been designed to cover point (d) of AS unit 1, topic 2 of the WJEC A-level Biology specification and focuses on the levels of organisation in humans and plants. Please note that the lesson does not contain prepared slides of tissue as this is covered in a later lesson. The lesson begins by using the process of haematopoiesis from haematopoietic stem cells to demonstrate how the red blood cell and neutrophil differ significantly in structure despite arising from the same cell along the same cell lineage. A series of exam-style questions will not only challenge their knowledge of structure but also their ability to apply this knowledge to unfamiliar situations. These differences in cell structure is further exemplified by the epithelial cells of the respiratory tract and students are challenged to remember how the shape and arrangement of these cells differ in the trachea and alveoli in relation to their function. The link between specialised cells and tissues is made at this point of the lesson so students are reminded that a tissue is a group of cells that work together to perform a specific function or set of functions. Moving forwards, a quick quiz competition will challenge the students to recognise the liver, kidney, spinal cord and pancreas from a brief functional description and this leads into a series of questions that links back to topics 1 and earlier in topic 2 where proteins, organelles and carbohydrates were originally covered. These prior knowledge checks are found throughout the lesson, along with current understanding checks, and all of the mark schemes are embedded into the PowerPoint to allow students to assess their progress. In terms of organ systems, a quick task challenges them to recognise 8 of the 11 that are found in humans from descriptions and this leaves them to identify the gaseous exchange, digestive and reproductive systems as the remaining 3. The remainder of the lesson focuses on specialised plant cells and the differing shapes and features of the palisade and spongy cells in the mesophyll layer and the guard cells are covered at length and in detail. The cells found in the xylem and phloem tissue are also discussed.

This lesson describes how the cells of multicellular organisms are organised into tissues, tissues into organs and organs into systems. The detailed and engaging PowerPoint and accompanying resources have been designed to cover point 3.13 of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification and focuses on the levels of organisation in humans and plants The lesson begins by using the process of haematopoiesis from haematopoietic stem cells to demonstrate how the red blood cell and neutrophil differ significantly in structure despite arising from the same cell along the same cell lineage. A series of exam-style questions will not only challenge their knowledge of structure but also their ability to apply this knowledge to unfamiliar situations. These differences in cell structure is further exemplified by the epithelial cells of the respiratory tract and students are challenged to remember how the shape and arrangement of these cells differ in the trachea and alveoli in relation to their function. The link between specialised cells and tissues is made at this point of the lesson so students are reminded that a tissue is a group of cells that work together to perform a specific function or set of functions. Moving forwards, a quick quiz competition will challenge the students to recognise the liver, kidney, spinal cord and pancreas from a brief functional description and this leads into a series of questions that links back to topics 1 and 2 and earlier in topic 3 where blood clotting, proteins, osmosis, organelles, methods of transport, carbohydrates and enzymes were originally covered. These prior knowledge checks are found throughout the lesson, along with current understanding checks, and all of the mark schemes are embedded into the PowerPoint to allow students to assess their progress. In terms of organ systems, a quick task challenges them to recognise 8 of the 11 that are found in humans from descriptions and this leaves them to identify the gaseous exchange, digestive and reproductive systems as the remaining 3. This leads into a section about cystic fibrosis as this genetic disorder impairs the functioning of these systems. The remainder of the lesson focuses on specialised plant cells and the differing shapes and features of the palisade and spongy cells in the mesophyll layer and the guard cells are covered at length and in detail. The cells found in the xylem and phloem tissue are also discussed.

This lesson describes how the expression of a gene mutation impairs the functioning of the gaseous and digestive systems in people with cystic fibrosis. The detailed PowerPoint and accompanying worksheets have primarily been designed to cover points 2.12 (ii) and 2.14 of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification but also challenges the students on their knowledge of previously-covered topics including monohybrid inheritance, protein synthesis, genetic code and blood clotting as well as making links to the upcoming topics of loci, organisation of multicellular organisms and post-transcriptional changes. The main focus of the lesson is the CFTR gene and the functions of the ion channel that is synthesised when this gene is expressed. As well as explaining that this channel allows chloride ions to flow across the apical membrane of the epithelial cells, time is taken to emphasise the importance of its inhibition on the ENaC, which prevents the flow of sodium ions back into the cells. A step by step guide is then used to describe the sequence of events that result in mucus which is motile and can be moved by the wafting action of the cilia in healthy individuals. This leads into the section of the lesson which considers the inheritance of cystic fibrosis in an autosomal recessive manner and then focuses on the change in the primary structure of the channel which results from one of over 1500 different gene mutations. Again, the students are guided through the events that lead to the depletion of the apical surface liquid and the cilia being unable to move the viscous mucus. Although the majority of the lesson is described with reference to the gaseous exchange system, the impaired functioning of the digestive system in terms of the blockage of the pancreas and liver secretions is considered and discussed and the students are challenged on their understanding through a range of exam-style questions. All of the questions included in the lesson have mark schemes which are embedded into the PowerPoint and this allows the students to assess their progress. Due to the detailed content of this lesson, it is estimated that it will take in excess of 3 hours of allocated A-level teaching time to cover

This lesson describes how the expression of a gene mutation impairs the functioning of the organ systems in people with cystic fibrosis. The detailed PowerPoint and accompanying worksheets have primarily been designed to cover point 2.16 in AS unit 1 of the Edexcel International A-level Biology specification but also challenge the students on their knowledge of previously-covered topics such as inheritance, protein synthesis and the genetic code as well as making links to the upcoming topics of loci and post-transcriptional changes. The main focus of the lesson is the CFTR gene and the functions of the ion channel that is synthesised when this gene is expressed. As well as explaining that this channel allows chloride ions to flow across the apical membrane of the epithelial cells, time is taken to emphasise the importance of its inhibition on the ENaC, which prevents the flow of sodium ions back into the cells. A step by step guide is then used to describe the sequence of events that result in mucus which is motile and can be moved by the wafting action of the cilia in healthy individuals. This leads into the section of the lesson which considers the inheritance of cystic fibrosis in an autosomal recessive manner and then focuses on the change in the primary structure of the channel which results from one of over 1500 different gene mutations. Again, the students are guided through the events that lead to the depletion of the apical surface liquid and the cilia being unable to move the viscous mucus. Although the majority of the lesson is described with reference to the gaseous exchange system, the impaired functioning of the digestive system in terms of the blockage of the pancreas and liver secretions is considered and discussed and the students are challenged on their understanding through a range of exam-style questions. All of the questions included in the lesson have mark schemes which are embedded into the PowerPoint and this allows the students to assess their progress. Due to the detailed content of this lesson, it is estimated that it will take in excess of 3 hours of allocated A-level teaching time to cover

This lesson describes the mechanisms of ventilation and gas exchange in insects. The PowerPoint and accompanying worksheets are the part of the second lesson in a series of 2 lessons which have been designed to cover the details that are set out in point 3.1.1 (f) of the OCR A-level Biology A specification. The first lesson in this series describes ventilation and gas exchange in bony fish In the previous lesson, the students were introduced to the different circulatory systems of mammals and bony fish and this knowledge is checked upon at the start of this lesson. This is relevant because the open circulatory system of an insect explains how oxygen is not transported in the blood but instead is absorbed from the body fluid that bathes the tissues. The next part of the lesson describes the structure of the spiracles, tracheae and tracheoles in the tracheal system and explains how this system is responsible for the delivery of oxygen to the open end of the tracheole for gas exchange with this fluid. As the tracheae are supported by chitin, which is similar in structure and function to cellulose and keratin respectively, a series of exam-style questions are used to challenge the students on their knowledge of those polymers from module 2.1.2 (biological molecules). As always, the mark scheme is embedded in the powerpoint so students can assess their understanding and progress. The final part of the lesson describes how squeezing of the tracheoles by the flight muscles and the changes in the volume of the thorax as a result of the movement of the wings are similar to mechanisms observed in mammals.

This lesson describes how the surfaces in insects, fish and mammals are adapted for gas exchange. The PowerPoint and accompanying worksheets have been designed to cover the detail of point 4.3 (i) of the Edexcel A-level Biology B specification. The lesson has been intricately planned to challenge the students on their understanding of the surface area to volume ratio (as covered in topic 4.1) and to make direct links to upcoming lessons on the transport systems in humans. The lesson begins by explaining that single-celled organisms are able to diffuse oxygen and carbon dioxide across their body surface but that as organisms increase in size and their SA/V ratio decreases, they need adaptations at their gas exchange surfaces to be able to obtain the oxygen to meet their metabolic demands. This leads into the next part of the lesson which describes the roles of the following structures in insects and bony fish: spiracles, tracheae, tracheoles and tracheole fluid operculum, gill arch, gill filaments and lamellae The next task challenges the students to use their knowledge of topics 1, 2 and 3 to come up with the letters that form the key term, countercurrent flow. This is a key element of the lesson and tends to be a principle that is poorly understood, so extra time is taken to explain the importance of this mechanism. Students are shown two diagrams, where one contains a countercurrent system and the other has the two fluids flowing in the same direction, and this is designed to support them in recognising that this type of system ensures that the concentration of oxygen is always higher in the oxygenated water than in the blood in the lamellae. As the alveoli as a structure of gas exchange was introduced at GCSE, this final part of the lesson has been written to challenge the recall of that knowledge and to build on it. The main focus is the type of epithelium found lining the alveoli and students will discover that a single layer of flattened cells known as simple, squamous epithelium acts to reduce the diffusion distance. Again, students will have met this in a lesson in topic 2 on specialised cells (and tissues) so a number of prior knowledge checks are used alongside current understanding checks. The following features of the alveolar epithelium are also covered: Surface area Moist lining Production of surfactant The maintenance of a steep concentration gradient As a constant ventilation supply is critical for the maintenance of the steep concentration gradient, the final task considers the mechanism of ventilation

This lesson describes the adaptations of gas exchange surfaces in single-celled organisms, insects, bony fish and dicotyledonous plants. The PowerPoint and accompanying worksheets are part of the first lesson in a series of 6 lessons that have been designed to cover the detail of point 3.2 (Gas exchange) of the AQA A-level Biology specification. The lesson has been intricately planned to challenge the students on their understanding of the surface area to volume ratio (as covered in the previous lesson) and to make direct links to upcoming lessons on gas exchange and transport systems in humans. The lesson begins by explaining that single-celled organisms are able to diffuse oxygen and carbon dioxide across their body surface but that as organisms increase in size and their SA/V ratio decreases, they need adaptations at their gas exchange surfaces to be able to obtain the oxygen to meet their metabolic demands. This leads into the next part of the lesson which describes the roles of the following structures in insects and bony fish: spiracles, tracheae, tracheoles and tracheole fluid operculum, gill arch, gill filaments and lamellae The next task challenges the students to use their knowledge of topics 1 and 2 to come up with the letters that form the key term, countercurrent flow. This is a key element of the lesson and tends to be a principle that is poorly understood, so extra time is taken to explain the importance of this mechanism. Students are shown two diagrams, where one contains a countercurrent system and the other has the two fluids flowing in the same direction, and this is designed to support them in recognising that this type of system ensures that the concentration of oxygen is always higher in the oxygenated water than in the blood in the lamellae. The final part of the lesson describes the role of the stomata and the mesophyll cells in the gas exchange of a dicotyledonous plant. Students will learn that guard cells contain chloroplasts which generate ATP and then they are challenged to order a series of statements to form a description of the events that result in the opening of the stomata. The differing structures of the spongy mesophyll and palisade mesophyll cells are then considered before the students are challenged to explain how carbon dioxide moves through the leaf after entering via the stomata and then how water vapour and oxygen leave. Clear links are made to the loss of water vapour by transpiration so students are prepared for the lessons covering this biological process later in topic 3.

This lesson describes the roles of the buccal cavity, operculum, gill lamellae and countercurrent flow in ventilation and gas exchange in bony fish. The detailed PowerPoint and accompanying resources are part of the first lesson in a series of 2 that have been designed to cover the details of point 3.1.1 (f) of the OCR A-level Biology A specification. The second lesson in this series covers the mechanisms of ventilation and gas exchange in insects. The lesson has been specifically planned to prepare students for the content of module 3.1.2 (Transport in animals) and therefore begins with an introduction and a brief description of the single circulatory system of a fish as this has an impact on the delivery of deoxygenated blood to the lamellae. A quick quiz competition is used to introduce the operculum and then the flow of blood along the gill arch and into the primary lamellae and then into the capillaries in the secondary lamellae is described. The next task challenges the students to use their knowledge of module 2 to come up with the letters that form the key term, countercurrent flow. This is a key element of the lesson and tends to be a feature that is poorly understood, so extra time is taken to explain the importance of this mechanism. Students are shown two diagrams, where one contains a countercurrent system and the other has the two fluids flowing in the same direction, and this is designed to support them in recognising that this type of system ensures that the concentration of oxygen is always higher in the oxygenated water than in the blood in the lamellae. The remainder of the lesson focuses on the coordinated movements of the buccal-opercular pump to ensure that the water continues to flow over the gills. Current understanding and prior knowledge checks are included throughout the lesson and students can assess their progress against the mark schemes which are embedded into the PowerPoint

This lesson explains the meaning of biodiversity and describes how it can be assessed in a habitat, in a species level at a genetic level and at a molecular level. The engaging PowerPoint and accompanying resources have been designed to cover points (h-l) in AS unit 2, topic 1 of the WJEC A-level Biology specification but as a lot of genetic content is covered when considering diversity within a species, this lesson can be used as an introduction to the upcoming topics of inheritance A quiz competition called BIOLOGICAL TERMINOLOGY SNAP runs over the course of the lesson and this will engage the students whilst challenging them to recognise key terms from their definitions. This quiz introduces biodiversity, loci, allele and recessive and each of these terms is put into context once introduced. Once biodiversity has been revealed, the students will learn that they are expected to be able to assess the biodiversity within a habitat and within a species and at a molecular level. The variety of alleles in the gene pool of a population increases the genetic diversity so a number of examples are used to demonstrate how the number of phenotypes increases with the number of alleles at a locus. The CFTR gene is used to demonstrate how 2 alleles results in 2 different phenotypes and therefore genetic diversity. Moving forwards, students will discover that more than 2 alleles can be found at a locus and they are challenged to work out genotypes and phenotypes for a loci with 3 alleles (shell colour in snails) and 4 alleles (coat colour in rabbits). Moving forwards, a step by step guide to complete a worked example to calculate a value of D using Simpson’s index of diversity. Students are challenged with a range of exam-style questions where they have to apply their knowledge and all mark schemes are displayed and clearly explained within the PowerPoint to allow students to assess their understanding and address any misconceptions if they arise. The final part of the lesson considers how DNA fingerprinting can be used to assess biodiversity at a molecular level and again a series of exam-style questions are used to challenge the students to apply their newly-acquired knowledge to an unfamiliar situation.

This lesson introduces the three-domain system and describes some of the biochemical methods used in classification to overcome the problems of morphological convergence. The PowerPoint and accompanying resources have been designed to cover points [c] and [e] in AS unit 2, topic 1 of the WJEC A-level Biology specification The lesson begins with an introduction of Carl Woese and goes on to describe how he is most famous for his definition of the Archaea as a new domain of life. Students were introduced to domains and the other classification taxa in a previous lesson, so their recall of this knowledge is continually tested and built upon as details are added. Students will discover the key differences between Archaea and Bacteria that led to the splitting of the prokaryotae kingdom and the addition of this higher classification rank. Moving forwards, the rest of the lesson considers other molecules that can be compared between species for classification purposes and the primary structure of cytochrome is described and discussed. At this point in the lesson, the students are also tested on their knowledge of the nature of the genetic code and have to explain how mutations to DNA can also be used for comparative purposes. The use of DNA genetic fingerprinting is briefly introduced and this is described in greater detail in a future lesson about assessing biodiversity at a molecular level