This fully-resourced lesson describes how reproductive isolation can lead to allopatric and sympatric speciation. The engaging PowerPoint and accompanying resources have been designed to cover point 3.2 (iii) of the Edexcel A-level Biology B specification. The lesson begins by using the example of a hinny, which is the hybrid offspring of a horse and a donkey, to challenge students to recall the biological classification of a species. Moving forwards, students are introduced to the idea of speciation and the key components of this process, such as isolation and selection pressures, are covered and discussed in detail. Understanding and prior knowledge checks are included throughout the lesson to allow the students to not only assess their progress against the current topic but also to make links to earlier topics in the specification. Time is taken to look at the details of allopatric speciation and how the different mutations that arise in the isolated populations and genetic drift will lead to genetic changes. The example of allopatric speciation in wrasse fish because of the isthmus of Panama is used to allow the students to visualise this process. The final part of the lesson considers sympatric speciation and again a wide variety of tasks are used to enable a deep understanding to be developed.

This fully-resourced lesson describes how evolution can come through natural selection and acts on variation to bring about adaptations. The PowerPoint and accompanying resources have been designed to cover specification points 3.2 (i) & (ii) of the Edexcel A-level Biology B specification and considers a range of different behavioural, anatomical and physiological adaptations. President Trump’s error ridden speech about antibiotics is used at the beginning of the lesson to remind students that this is a treatment for bacterial infections and not viruses as he stated. 2 quick quiz competitions are used to introduce MRSA and then to get the students to recognise that they can use this abbreviation to remind them to use mutation, reproduce, selection (and survive) and allele in their descriptions of evolution through natural selection. The main task of the lesson challenges the students to form a description that explains how this strain of bacteria developed resistance to methicillin to enable them to see the principles of natural selection. This can then be used when describing how the anatomy of the modern-day giraffe has evolved over time. The concept of convergent evolution is introduced and links are made to the need for modern classification techniques. Moving forwards, students will understand how natural selection leads to adaptations and a quick quiz competition introduces the different types of adaptation and a series of tasks are used to ensure that the students can distinguish between anatomical, behavioural and physiological adaptations. The Marram grass is used to test their understanding further, before a step by step guide describes how the lignified cells prevent a loss of turgidity. Moving forwards, the students are challenged to explain how the other adaptations of this grass help it to survive in its environment. The final part of the lesson focuses on the adaptations of the anteater and links are made to the topic of classification hierarchy which was covered at the start of topic 3… Due to the extensiveness of this lesson and the detail contained within the resources, it is estimated that it will take in excess of 2 hours of allocated A-level teaching time to deliver this lesson.

This fully-resourced lesson describes how biodiversity can be assessed within a habitat at a species level and within a species at a genetic level. The engaging PowerPoint and accompanying resources have been primarily designed to cover point 3.3 (i) of the Edexcel A-level Biology B 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 topic 8 material… 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 species, population, biodiversity, allele, recessive and dominant 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. 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). At this point, the students are introduced to codominance and again they are challenged to apply their understanding to a new situation by working out the number of phenotypes in the inheritance of blood groups. The rest of the lesson uses a step by step guide to complete a worked example to calculate an 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.

This lesson describes the classification system that consist of a hierarchy of domain, kingdom, phylum, class, order, family, genus and species. The engaging PowerPoint and accompanying resource have been designed to cover point 3.1 (i) of the Edexcel A-level Biology B specification and also includes details of the use of the binomial naming system. The lesson begins by looking at the meaning of a population in Biology so that the term species can be introduced. A hinny, which is the hybrid offspring of a male horse and a female donkey, is used to explain how these two organisms must be members of different species because they are unable to produce fertile offspring. Moving forwards, students will learn that species is the lowest taxon in the modern-day classification hierarchy. A quiz runs throughout the lesson and this particular round will engage the students whilst they learn the names of the other 7 taxa and the horse and the donkey from the earlier example are used to complete the hierarchy. Students will understand that the binomial naming system was introduced by Carl Linnaeus to provide a universal name for each species and they will be challenged to apply their knowledge by completing a hierarchy for a modern-day human, by spotting the correct name for an unfamiliar organism and finally by suggesting advantages of this system.

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.

This fully-resourced lesson explains the meaning of biodiversity and describes how it can be calculated within a habitat and within a species. The engaging PowerPoint and accompanying resources have been designed to cover point 4.2 of the Pearson Edexcel A-level Biology A specification and in addition to biodiversity, the meaning of endemism is also explained. 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 will introduce species, population, biodiversity, endemic, heterozygote and natural selection 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 measure biodiversity within a habitat, within a species and within different habitats so that they can be compared. The rest of the lesson uses step by step guides, discussion points and selected tasks to demonstrate how to determine species richness, the heterozygosity index and an 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.

This lesson describes the role of haemoglobin in transport and explains the change in the dissociation curve when there is an increased concentration of carbon dioxide (the Bohr effect). The detailed PowerPoint and accompanying resources have been designed to cover points 1.9 (i) & (ii) of the Edexcel International A-level Biology specification and this lesson also compares the oxyhaemoglobin dissociation curve of foetal haemoglobin against maternal haemoglobin. The lesson begins with a version of the quiz show Pointless and this introduces haemotology as the study of the blood conditions. Students are told that haemoglobin has a quaternary structure as it is formed of 4 polypeptide chains which each contain a haem group with an iron ion attached and that it is this group which has a high affinity for oxygen. Time is taken to discuss how this protein must be able to load (and unload) oxygen as well as transport the molecules to the respiring tissues. Students will plot the oxyhaemoglobin dissociation curve and the S-shaped curve is used to encourage discussions about the ease with which haemoglobin loads each molecule. At this point, foetal haemoglobin and its differing affinity of oxygen is introduced and students are challenged to predict whether this affinity will be higher or lower than adult haemoglobin and to represent this on their dissociation curve. Moving forwards, the different ways that carbon dioxide is transported around the body involving haemoglobin are described and the dissociation of carbonic acid into hydrogen ions is discussed so that students can understand how this will affect the affinity of haemoglobin for oxygen in the final part of the lesson on the Bohr effect. A quick quiz is used to introduce Christian Bohr and the students are given some initial details of his described effect. This leads into a series of discussions where the outcome is the understanding that an increased concentration of carbon dioxide decreases the affinity of haemoglobin for oxygen. The students will learn that this reduction in affinity is a result of a decrease in the pH of the cell cytoplasm which alters the tertiary structure of the haemoglobin. The lesson finishes with a series of questions where the understanding and application skills are tested as students have to explain the benefit of the Bohr effect for an exercising individual.

This fully-resourced lesson describes the key events that occur during the three stages of the cardiac cycle and relates these to the structure of the mammalian heart. The engaging and detailed PowerPoint and accompanying resources have been designed to cover point 1.8 of the Edexcel International A-level Biology specification As the structure of the heart was covered at iGCSE, the lesson has been planned to build on this prior knowledge whilst adding the key details which will enable students to provide A-level standard answers. The primary focus is the identification of the different structures of the heart but it also challenges their ability to recognise the important relationship to function. For example, time is taken to ensure that students can explain why the atrial walls are thinner than the ventricular walls and why the right ventricle has a thinner wall than the left ventricle. Opportunities are taken throughout the lesson to link this topic to the others found in topic 1 including those which have already been covered like the blood vessels. There is also an application question where students have to explain why a hole in the ventricular septum would need to be repaired if it doesn’t naturally close over time. The next part of the lesson introduces the cardiac cycle through the use of quick quiz competition which generates the key term systole. Students will learn that there are three stages in the cycle are atrial and ventricular systole followed by cardiac diastole and that the uni-directional movement of blood during these stages is maintained by the atrioventricular and semi-lunar valves. This leads into the emphasis of the key point that pressure changes in the chambers and the major arteries is the cause of the opening and closing of these sets of valves. Students are given a description of the pressure change that results in the opening of the AV valves and shown where this would be found on the graph detailing the pressure changes of the cardiac cycle. They then have to use this as a guide to write descriptions for the closing of the AV valve and the opening and closing of the semi-lunar valves and to locate these on the graph. By providing the students with this graph, the rest of the lesson can focus on explaining how these changes come about. Students have to use their current and prior knowledge of the chambers and blood vessels to write 4 descriptions that cover the cardiac cycle. The final part of the lesson covers the changes in the volume of the ventricle. It is estimated that it will take in excess of 2 hours of allocated A-level teaching time to cover the detail included in this lesson as required by this specification point

This fully-resourced lesson explores how the structure of capillaries, arteries and veins relate to their functions. The engaging and detailed PowerPoint and accompanying resources have been designed to cover point 1.7 of the Edexcel International A-level Biology specification. This lesson has been written to build on any prior knowledge from iGCSE or earlier in this topic to enable students to fully understand each type of blood vessel has its particular features. Students will be able to make the connection between the narrow lumen and elastic tissue in the walls of arteries and the need to maintain the high pressure of the blood. A quick version of GUESS WHO is used to introduce smooth muscle and collagen as the substances that are found in the tunica media and externa and again the reason for their presence is explored and explained. The next part of the lesson looks at the role of the capillaries in exchange and links are made to diffusion to ensure that students can explain how the red blood cells pressing against the endothelium results in a short diffusion distance. The remainder of the lesson considers the structure of the veins and students are challenged to explain how the differences to those observed in arteries is due to the lower blood pressure found in these vessels. Valves are introduced and important mechanisms like the skeletal muscle pump are discussed to ensure that students can understand how the return of blood to the right atrium of the heart is maintained.

This fully-resourced lesson describes how a triglyceride is synthesised and describes the differences between saturated and unsaturated lipids. The engaging PowerPoint and accompanying resources have been designed to cover specification points 1.5 (i) & (ii) as detailed in the Edexcel International A-level Biology specification and links are also made to related future topics such as the use of lipids as a substrate for respiration and the importance of the myelin sheath for the conduction of an electrical impulse. The lesson begins with a focus on the basic structure and roles of lipids, including the elements that are found in this biological molecule and some of the places in living organisms where they are found. Moving forwards, the students are challenged to recall the structure of the carbohydrates from earlier in topic 1 so that the structure of a triglyceride can be introduced. Students will learn that this macromolecule is formed from one glycerol molecule and three fatty acids and have to use their understanding of condensation reactions to draw the final structure. Time is taken to look at the difference in structure and properties of saturated and unsaturated fatty acids and students will be able to identify one from the other when presented with a molecular formula. The final part of the lesson explores how the various properties of lipids mean that these molecules have numerous roles in organisms including that of an energy store and source and as an insulator of heat and electricity.

This fully-resourced lesson describes how polygenic inheritance gives rise to phenotypes that show continuous variation. The engaging PowerPoint and accompanying resources have been primarily designed to cover points 3.20 (i) & 3.21 of the Edexcel International A-level Biology specification but also includes activities to challenge the students on previous concepts in topics 3 and 2. The students begin the lesson by having to identify phenotype and species from their respective definitions so that a discussion can be encouraged where they will recognise that phenotypic variation within a species is due to both genetic and environmental factors. The main part of the the lesson focuses on these genetic factors, and describes how mutation and the events of meiosis contribute to this variation. A range of activities, which include exam-style questions and quick quiz rounds, are used to challenge the students on their knowledge and understanding of substitution mutations, deletions, insertions, the genetic code, crossing over and independent assortment. Moving forwards, the concept of multiple alleles is introduced and students will learn how the presence of more than 2 alleles at a locus increases the number of phenotypic variants. Another quick quiz round is used to introduce polygenic inheritance and the link is made between this inheritance of genes at a number of loci as an example of continuous variation. The final part of the lesson describes a few examples where environmental factors affect phenotype, such as chlorosis in plants. As this is the final lesson in topic 3, the numerous activities can be used for revision purposes and to demonstrate the links between different biological topics.

This fully-resourced lesson describes how post-transcriptional changes to mRNA enable 1 gene to give rise to multiple proteins. The detailed PowerPoint and accompanying resources have been designed to cover point 3.19 of the Edexcel International A-level Biology specification. The lesson begins with a knowledge recall as the students have to recognise the definition of a gene as a sequence of bases on a DNA molecule that codes for a sequence of amino acids in a polypeptide chain. This description was introduced in topic 2 and the aim of the start of the lesson is to introduce the fact that despite this definition, most of the nuclear DNA in eukaryotes doesn’t actually code for proteins. A quick quiz competition is then used to introduce exons as the coding regions within a gene before students are challenged to predict the name of the non-coding regions and then to suggest a function for these introns. Moving forwards, pre-mRNA as a primary transcript is introduced and students will learn that this isn’t the mature strand that moves off to the ribosome for translation. Instead, a process called splicing takes place where the introns are removed and the remaining exons are joined together. Another quick quiz round leads to an answer of 20000 and students will learn that this is the number of protein-coding genes in the human genome. Importantly, the students are then told that the number of proteins that are synthesised is much higher than this value and a class discussion period encourages them to come up with biological suggestions for this discrepancy between the two numbers. The lesson concludes with a series of understanding and application questions where students will learn that alternative splicing enables a gene to produce more than a single protein and that this natural phenomenon greatly increases biodiversity.

This fully-resourced lesson describes how cells become specialised through differential gene expression. The PowerPoint and accompanying resources have been designed to cover the details of point 3.19 of the Edexcel International A-level Biology specification. This is one of the more difficult concepts in this A-level course and therefore key points are reiterated throughout this lesson to increase the likelihood of student understanding and to support them when trying to make links to actual biological examples in living organisms. There is a clear connection to transcription and translation as covered in topic 2, so the lesson begins by reminding students that in addition to the structural gene in a transcription unit, there is the promotor region where RNA polymerase binds. Students are introduced to the idea of transcription factors and will understand how these molecules can activate or repress transcription by enabling or preventing the binding of the enzyme. At this point, students are challenged on their current understanding with a series of questions about DELLA proteins so they can see how these molecules prevent the binding of RNA polymerase. The final section of the lesson looks at one further example with oestrogen and the ER receptor and explains how the binding of this chemical results in the release of the inhibitor and the production of active mRNA.

This fully-resourced lesson describes the role of mitosis and the cell cycle in producing genetically identical daughter cells. The detailed PowerPoint and accompanying resources have been designed to cover point 3.14 of the Edexcel International A-level Biology specification and explains the importance of these cells for growth and asexual reproduction. In an earlier lesson covering meiosis (3.10), students were introduced to the different phases and structures involved in the cycle so this lesson builds on that by providing greater detail of the key events in each phase. Beginning with a focus on interphase, the importance of DNA replication is explained so that students can initially recognise that there are pairs of identical sister chromatids and then can understand how they are separated later in the cycle. A quiz competition has been written into the lesson and this runs throughout, challenging the students to identify the quantity of DNA in the cell (in terms of n) at different points of the cycle. The main part of the lesson focuses on prophase, metaphase, anaphase and telophase and describes how the chromosomes behave in these stages. Students will understand how the cytoplasmic division that occurs in cytokinesis results in the production of genetically identical daughter cells. This leads into a series of understanding and application questions where students have to identify the various roles of mitosis in living organisms as well as tackling a Maths in a Biology context question. The lesson concludes with a final round of MITOSIS SNAP where they only shout out this word when a match is seen between the name of a phase, an event and a picture.

This detailed lesson describes how the crossing over of alleles and the independent assortment in meiosis contribute to genetic variation. The PowerPoint and accompanying resource have been designed to cover specification point 3.10 of the Edexcel International A-level Biology specification and includes describes how the fertilisation of the haploid gametes that were formed by meiosis increases variation further. In order to understand how the events of meiosis like crossing over and random assortment and independent segregation can lead to variation, students need to be clear in their understanding that DNA replication in interphase results in homologous chromosomes as pairs of sister chromatids. Therefore the beginning of the lesson focuses on the chromosomes in the parent cell and this first part of the cycle and students will be introduced to non-sister chromatids and the fact that they may contain different alleles which is important for the exchange that occurs during crossing over. Time is taken to go through this event in prophase I in a step by step guide so that the students can recognise that the result can be new combinations of alleles that were not present in the parent cell. Moving forwards, the lesson explores how the independent segregation of chromosomes and chromatids during anaphase I and II results in genetically different gametes. The final part of the lesson looks at the use of a mathematical expression to calculate the possible combinations of alleles in gametes as well as in a zygote following the random fertilisation of haploid gametes. Understanding and prior knowledge checks are interspersed throughout the lesson as well as a series of exam questions which challenge the students to apply their knowledge to potentially unfamiliar situations.

This clear and concise lesson describes the meaning of a gene locus and explains how the inheritance of two or more genes that have loci on the same chromosome demonstrates linkage. The engaging PowerPoint and associated resource have been designed to cover points 3.9 (i) and (ii) of the Edexcel International A-level Biology specification and makes clear links to the upcoming topic of meiosis when describing the effect of crossing over on this linkage This is a topic which can cause confusion for students so time was taken in the design to split the concept into small chunks. There is a clear focus on how the number of original phenotypes and recombinants can be used to determine linkage and suggest how the loci of the two genes compare. Important links to other topics such as crossing over in meiosis are made to enable students to understand how the random formation of the chiasma determines whether new phenotypes will be seen in the offspring or not. Linkage is an important cause of variation and the difference between observed and expected results and this is emphasised on a number of occasions. The main task of the lesson acts as an understanding check where students are challenged to analyse a set of results involving the inheritance of the ABO blood group gene and the nail-patella syndrome gene to determine whether they have loci on the same chromosome and if so, how close their loci would appear to be.

This fully-resourced lesson describes how magnification and resolution can be achieved using light and electron microscopy. The engaging PowerPoint and accompanying resources have been designed to cover the content of points 3.7 (i) & (ii) of the Edexcel International A-level Biology specification and also considers how specimens are stained. To promote engagement and focus throughout this lesson, the PowerPoint contains a quiz competition with 7 rounds. The quiz rounds found in this lesson will introduce the objective lens powers, the names of the parts of a light microscope and emphasise some of the other key terms such as resolution. The final round checks on their understanding of the different numbers that were mentioned in the lesson, namely the differing maximum magnifications and resolutions. Time is taken to explain the meaning of both of these microscopic terms so that students can recognise their importance when considering the organelles that were met earlier in topic 3. By the end of the lesson, the students will be able to explain how a light microscope uses light to form an image and will understand how electrons transmitted through a specimen or across the surface will form an image with a TEM or a SEM respectively.

This fully-resourced lesson describes the ultrastructure of a prokaryotic cell and the function of the structures found in these cells. The engaging PowerPoint and accompanying resources have been designed to cover specification point 3.5 (i) & (ii) as detailed in the Edexcel International A-level Biology specification and also compares these cells against the eukaryotic cells that were met in the previous lesson. A clear understanding of terminology is important for A-level Biology so this lesson begins with a challenge, where the students have to recognise a prefix that they believe translates as before or in front of . This leads into the discovery of the meaning of prokaryote as before nucleus and this 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