This lesson evaluates the methods used by zoos and seed banks in the conservation of endangered species and their genetic diversity. The PowerPoint and accompanying resources have been primarily designed to cover point 4.21 of the Edexcel International A-level Biology specification but as this is potentially the last lesson in this topic, lots of questions and activities have been included that will challenge the students on their knowledge and understanding of topic 4 (Plant structure and function, Biodiversity and Conservation). Hours of research went into the planning of this lesson to source interesting examples and although the main focus of the lesson is the zoo and seed banks as ex situ conservation methods, the lesson begins with a consideration of the importance of the in situ methods that are used in the Lake Télé Community reserve in the Republic of Congo and the marine conservation zone in the waters surrounding Tristan da Cunha. Students will learn how this form of active management conserves habitats and species in their natural environment, with the aim of minimising human impact whilst maintaining biodiversity. To enrich their understanding of ex situ conservation, the well-known examples of ZSL London zoo, Kew Gardens and the Millennium Seed Bank Project in Wakehurst are used. Students will understand how conserving animal species outside of their natural habitat allows for human intervention that ensures the animals are fed and given medical assistance when needed as well as reproductive assistance to increase the likelihood of the successful breeding of endangered species. An emphasis is placed on the desire to reintroduce the species into the wild and the example of some initial successes with the mountain chicken frog in Dominica and Montserrat is discussed. As stated in the specification point, these methods must be evaluated and therefore the issues are also considered and there is a focus on the susceptibility of captive populations to diseases as a result of their limited genetic diversity. The final part of the lesson considers how seed banks can be used to ensure that plant species, which may contain the molecules for medicine development, avoid extinction, and how the plants can be bred asexually to increase plant populations quickly. Due to the extensiveness of this lesson, it is estimated that it will take in excess of 2/3 hours of allocated A-level teaching time to cover the tasks and content included in the lesson and as explained above, it can also be used as revision of topic 4 content

This lesson discusses how biodiversity may be considered at different levels and describes how to calculate Simpson’s Index of diversity. The PowerPoint and accompanying worksheets have primarily been designed to cover points 4.2.1 (a, c and d) of the OCR A-level Biology A specification but also make links to the upcoming topics of classification, natural selection and adaptations 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 species, population, biodiversity, community and natural selection from their respective definitions. Once biodiversity as the variety of living organisms in a habitat is revealed, the students will learn that this can relate to a range of habitats, from those in the local area to the Earth. Moving forwards, the students will begin to understand that biodiversity can be considered at a range of levels which include within a habitat, within a species and within different habitats so that they can be compared. Species richness as a measure of the number of different species in a community is met and a biological example in the rainforests of Madagascar is used to increase its relevance. However, students will also be introduced to species evenness and will learn that in order for a habitat to be deemed to be biodiverse, it must be both species rich and even. The students are introduced to an unfamiliar formula that calculates the heterozygosity index and are challenged to apply their knowledge to this situation, as well as linking a low H value to natural selection. The rest of the lesson focuses on the calculation of Simpson’s Index of diversity and a 4-step guide is used to walk students through each part of the calculation. This is done in combination with a worked example to allow students to visualise how the formula should be applied to actual figures. Using the method, they will then calculate a value of D for a comparable habitat to allow the two values to be considered and the significance of a higher value is explained. All of the exam-style questions have mark schemes embedded in the PowerPoint to allow students to continuously assess their progress and understanding.

This lesson describes self and non-self antigens and how a failure to distinguish between the two is the mechanism of autoimmune diseases. The PowerPoint and accompanying worksheets have been primarily designed to cover points 11.1 (d & f) of the CIE A-level Biology specification and describe examples of these diseases including myasthenia gravis, but this lesson can also be used to revise the content of the earlier topics as well as the previous lessons in topic 10 & 11 through the range of activities that are included The first part of the lesson focuses on the antigens and explains how the failure of the immune system cells to recognise these molecules on the outside of a cell or organism elicits an immune response. Moving forwards, the students are challenged to recognise diseases from descriptions and then to use the first letters of their names to form the term, autoimmune. In doing so, the students will discover that rheumatoid arthritis, ulcerative colitis, type I diabetes mellitus, multiple sclerosis and myasthenia gravis are all examples of autoimmune diseases. The next part of the lesson focuses on the mechanism of these diseases where the immune system cells do not recognise the antigens (self-antigens) on the outside of the healthy cells, and therefore treats them as foreign antigens, resulting in the production of autoantibodies against proteins on these healthy cells and tissues. Key details of the autoimmune diseases stated above and lupus are described and links to previously covered topics as well as to future topics such as the pancreas and nervous system are made. The students will be challenged by the numerous exam-style questions, all of which have mark schemes embedded into the PowerPoint to allow for immediate assessment of progress.

This lesson describes the structure and function of synapses in nerve impulse transmission and focuses on acetylcholine as a neurotransmitter. The PowerPoint and accompanying resources have been designed to cover point 8.6 (i) of the Edexcel International A-level Biology specification, using a cholinergic synapse as the main example The lesson begins by using a version of the WALL from “Only Connect” which asks the students to group 12 words into three groups of 4. Not only will this challenge their prior knowledge from topics earlier in this topic but it will also lead to the discovery of four of the structures that are found in a synapse. Moving forwards, students are introduced to acetylcholine as the neurotransmitter involved at cholinergic synapses and they will start to add labels to the structures found in the pre-synaptic bulb. Time is taken to focus on certain structures such as the voltage gated channels as these types of channel were met previously when looking at the depolarisation of a neurone. There is plenty of challenge and discovery as students are pushed to explain why organelles like mitochondria would be found in large numbers in the bulb. With this process being a cascade of events, a bullet point format is used to ensure that the key content is taken in by the students and again key points like exocytosis and the action of acetylcholinesterase are discussed further. Understanding checks and prior knowledge checks are included throughout the lesson so that students can not only assess their progress against the current topic but also see whether they can make links to earlier topics.

This lesson explains how a nerve impulse (action potential) is conducted along an axon and focuses on the role of the sodium and potassium ions. The PowerPoint and accompanying resources have been designed to cover point 8.4 of the Edexcel International A-level Biology specification and contains detailed descriptions of resting potential, depolarisation, repolarisation, hyperpolarisation and the refractory period. This topic is commonly assessed in the terminal exams so extensive planning ensures that this resource includes a wide range of activities to motivate and engage the students whilst ensuring that the content is covered in the depth of detail that will allow them to have a real understanding. Interspersed within the activities are understanding checks and prior knowledge checks to enable the students to not only assess their progress against the current topic but also to challenge themselves on the links to earlier topics such as methods of movements across cell membranes. There are also a number of quiz competitions which are used to introduce key terms and values in a fun and memorable way and discussion points to encourage the students to consider why a particular process or mechanism occurs. Over the course of the lesson, the students will learn and discover how the movement of ions across the membrane causes the membrane potential to change. They will see how the resting potential is maintained through the use of the sodium/potassium pump and potassium ion leakage. There is a real focus on depolarisation to allow students to understand how generator potentials can combine and if the resulting depolarisation then exceeds the threshold potential, a full depolarisation will occur. At this point in the lesson students will discover how the all or nothing response explains that action potentials have the same magnitude and that instead a stronger stimulus is linked to an increase in the frequency of the transmission. The rest of the lesson challenges the students to apply their knowledge to explain how repolarisation and hyperpolarisation result and to suggest advantages of the refractory period for nerve cells.

This detailed lesson describes how recombinant DNA is produced using restriction endonucleases and DNA ligase and is inserted into other cells. The engaging PowerPoint and accompanying resources have been designed to cover points 8.18 & 8.19 of the Edexcel International A-level Biology specification. The lesson begins with a definition of genetic engineering and recombinant DNA to allow students to begin to understand how this process involves the transfer of DNA fragments from one species to another. Links are made to the genetic code and transcription and translation mechanisms, which were met in topic 2, in order to explain how the transferred gene can be translated in the transgenic organism. Moving forwards, the method involving reverse transcriptase and DNA polymerase is introduced and their knowledge of the structure of the polynucleotides and the roles of enzymes is challenged through questions and discussion points. Restriction endonucleases are then introduced and time is taken to look at the structure of a restriction site as well as the production of sticky ends due to the staggered cut on the DNA. A series of exam-style questions with displayed mark schemes are used to allow the students to assess their current understanding. The second half of the lesson looks at the culture of transformed host cells as an in vivo method to amplify DNA fragments. Students will learn that bacterial cells are the most commonly transformed cells so the next task challenges their recall of the structures of these cells so that plasmid DNA can be examined from that point onwards. Time is taken to explore the finer details of each step such as the addition of the promoter and terminator regions, use of the same restriction enzyme to cut the plasmid as was used to cut the gene and the different types of marker genes. As well as understanding and prior knowledge checks, quick quiz competitions are used throughout the lesson to introduce key terms such as cDNA and EcoR1 in a fun and hopefully memorable way

This lesson describes how tissue fluid is formed and reabsorbed in order to emphasise its importance as the link between the blood and cells. The PowerPoint and accompanying resources have been designed to cover point (h) in topic 3 of AS unit 2 of the WJEC A-level Biology specification and explains how a combination of the effects of hydrostatic pressure and oncotic pressure results in the formation of tissue fluid in animals. The lesson begins with an introduction to the arteriole and venule end of a capillary as these will need to be considered as separate entities when describing the formation of tissue fluid. A quick quiz competition introduces a value for the hydrostatic pressure at the arteriole end and students are challenged to first predict some parts of the blood will move out of the capillary as a result of the push from the hydrostatic pressure and this allows oncotic pressure to be initially explored. The main part of the lesson uses a step by step guide to describe how the net movement is outwards at the arteriole end before students will use this guidance to describe what happens at the venule end. In the concluding part of the lesson, students will come to recognise oedema as a condition where tissue fluid accumulates and they again are challenged to explain how this occurs before they finally learn how the fluid is returned to the circulatory system as lymph

This lesson describes the Krebs cycle as a stage of aerobic respiration that liberates energy to produce ATP and reduced NAD and releases carbon dioxide. The PowerPoint and accompanying resource have been designed to cover specification point [c] in topic 3 of A2 unit 3 of the WJEC A-level Biology specification. The lesson begins with a version of the Impossible game where students have to spot the connection between 8 of the 9 terms and will ultimately learn that this next stage is called the Krebs cycle. The main part of the lesson challenges the students to use descriptions of the main steps of the cycle to continue their diagram of the reactions. Students are continually exposed to key terminology such as decarboxylation and dehydrogenation and they will learn where carbon dioxide is lost and reduced NAD and FAD are generated. They will also recognise that ATP is synthesised by substrate level phosphorylation. The final task challenges them to apply their knowledge of the cycle to work out the numbers of the different products and to calculate the number of ATP that must be produced in the next stage This lesson has been designed to tie in with the other uploaded lessons on glycolysis and the electron transport chain (in oxidative phosphorylation).

This lesson describes how the cells of the proximal tubule in the nephron of the kidney are adapted for reabsorption. The PowerPoint and accompanying resource which is filled with tasks have been designed to cover specification point [e] in topic 7 of A2 unit 3 of the WJEC A-level Biology specification and builds on the knowledge gained in the previous lessons on the structure of the nephron and the functions of the mammalian kidney. The lesson begins by challenging the students to recall the substances that are found in the glomerular filtrate so that each of them can be considered over the course of the rest of the lesson. Moving forwards, the first of the numerous discussion points which are included in the lesson is used to get students to predict the component of the filtrate which won’t be found in the urine when they are presented with pie charts from each of these situations. Upon learning that glucose is 100% reabsorbed, along with most of the ions and some of the water, the rest of the lesson focuses on describing the relationship between the structure of the proximal tubule and the function of selective reabsorption. Again, this section begins by encouraging the students to discuss and to predict which structures they would expect to find in a section of the kidney if the function is to reabsorb. They are given the chance to see the structure (as shown in the cover image) before each feature is broken down to explain its importance. Time is taken to look at the role of the cotransporter proteins to explain how this allows glucose, along with sodium ions, to be reabsorbed from the lumen of the PCT into the epithelial cells. The final part of the lesson focuses on urea and how the concentration of this substance increases along the tubule as a result of the reabsorption of some of the water.

This fully-resourced lesson describes the range of potential treatments for kidney failure. The PowerPoint and accompanying resources have been designed to cover specification point (h) in topic 7 of A2 unit 3 of the WJEC A-level Biology specification. This lesson involves the diagnosis of a number of different kidney-related conditions and the potential treatments for kidney failure. This lesson is designed to get the students to take on the numerous roles of a doctor who works in the renal ward which include testing, diagnosis and treatment. Having obtained measurements by GFR and results by taking urine samples, hey are challenged to use their knowledge of the function of the kidney to study urine samples (and the accompanying GP’s notes) to diagnose one of four conditions. They then have to write a letter to the patient to explain how they made this diagnosis, again focusing on their knowledge of the structure and functions of the Bowman’s capsule and PCT. The rest of the lesson focuses on haemodialysis, peritoneal dialysis and kidney transplant. There are regular progress checks throughout the lesson so that students can assess their understanding and there are a number of homework activities included in the lesson.

This lesson describes the inheritance of two genes and guides students through the calculation of phenotypic ratios, before considering linkage. The PowerPoint and the accompanying resources have been designed to cover point [c] in topic 3 of A2 unit 4 of the WJEC A-level Biology specification. As the previous lesson described the construction of genetic crosses and pedigree diagrams, students are aware of the methods involved in writing genotypes and gametes for the inheritance of a single gene. Therefore, the start of this lesson builds on this understanding to ensure that students recognise that genotypes contain 4 alleles and gametes contain 2 alleles when two genes are inherited. The students are taken through the steps of a worked example to demonstrate the key steps in the calculation of a phenotypic ratio before 2 exam-style questions challenge them to apply their newly-acquired knowledge. Mark schemes are displayed within the PowerPoint to allow students to assess their progress. The phenotypic ratio generated as the answer to the next question is 9:3:3:1 and time is taken to explain that this is the expected ratio when two heterozygotes for two unlinked genes are crossed which they may be expected to use when meeting the chi squared test in an upcoming lesson The remainder of the lesson considers how linkage, where two genes have loci on the same chromosome, affects the outcome of dihybrid inheritance. This is a difficult topic which can be poorly understood by students so extra time was taken during the planning to split the concept into small chunks. There is a clear focus on using the number of parent phenotypes and recombinants in the offspring as a way 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 point of contact (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 and a link to the chi squared test which is covered in an upcoming lesson is also made. The main task of the lesson act as understanding check where students are challenged to analyse the results of genetic crosses involving the inheritance of the ABO blood group gene and the nail-patella syndrome gene n humans and also the inheritance of body colour and wing length in Drosophila.

This lesson describes sex linkage, focusing on the the inheritance of genes on the X chromosome that lead to haemophilia and Duchenne muscular dystrophy. The PowerPoint and accompanying resources have been designed to cover specification point [e] in topic 3 of A2 unit 4 of the WJEC A-level Biology specification. Key genetic terminology is used throughout and the lesson begins with a check on their ability to identify the definition of homologous chromosomes. Students will recall that the sex chromosomes are not fully homologous and that the smaller Y chromosome lacks some of the genes that are found on the X. This leads into one of the numerous discussion points, where students are encouraged to consider whether females or males are more likely to suffer from sex-linked diseases and they will be challenged to find evidence to support this decision later in the lesson. In terms of humans, the lesson focuses on haemophilia and a step-by-step guide is used to demonstrate how these specific genetic diagrams should be constructed and how the phenotypes should then be interpreted. The final tasks of the lesson challenge the students to carry out a dihybrid cross that involves a sex-linked disease and an autosomal disease before applying their knowledge to a question about chickens and how the rate of feather production in chicks can be used to determine gender. All of the tasks are differentiated so that students of differing abilities can access the work and all exam questions have fully-explained, visual markschemes to allow them to assess their progress and address any misconceptions

This detailed lesson describes how the movement of water between solutions and cells has differing effects on animal and plant cells. Both the PowerPoint and accompanying resources have been designed to cover specification points 4.2 (a) and (f) as detailed in the CIE International A-level Biology specification. It’s likely that students will have used the term concentration in their osmosis definitions at GCSE, so the aim of the starter task is to introduce water potential to allow students to begin to recognise osmosis as the movement of water molecules from a high water potential to a lower potential, with the water potential gradient. Time is taken to describe the finer details of water potential to enable students to understand that 0 is the highest value (pure water) and that this becomes negative once solutes are dissolved. Exam-style questions are used throughout the lesson to check on current understanding as well as prior knowledge checks which make links to previously covered topics such as the lipid bilayer of the cell membrane. The remainder of the lesson focuses on the movement of water when animal and plant cells are suspended in hypotonic, hypertonic or isotonic solutions and the final appearance of these cells is described, including any issues this may cause.

This fully-resourced lesson compares the structure and ultrastructure of a prokaryotic cell against an eukaryotic cell. The engaging PowerPoint and accompanying resources have been designed to cover specification point 2.1.1 (k) as detailed in the OCR A-level Biology A specification and describes how the size and cell structures differ as well as the additional features that are found in some prokaryotic cells and briefly introduces binary fission. 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 these cells do not contain centrioles