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 the concept of homeostasis using negative feedback control and also describes the role of positive feedback. The PowerPoint and accompanying resources have been designed to cover specification points (a & b) in topic 7 of A2 unit 3 of the WJEC A-level Biology specification and explains how this feedback control maintains systems within narrow limits but has also been planned to provide important details for upcoming topics such as osmoregulation. The normal ranges for blood glucose concentration, blood pH and body temperature are introduced at the start of the lesson to allow students to recognise that these aspects have to be maintained within narrow limits. A series of exam-style questions then challenge their recall of knowledge from AS units 1 & 2 and the earlier topics in A2 unit 3 as they have to explain why it’s important that each of these aspects is maintained within these limits. The students were introduced to homeostasis at GCSE, so this process is revisited and discussed, to ensure that students are able to recall that this is the maintenance of a state of dynamic equilibrium. A quick quiz competition is used to reveal negative feedback as a key term and students will learn how this form of control reverses the original change and biological examples are used to emphasise the importance of this system for restoring levels to the limits (and the optimum). The remainder of the lesson explains how positive feedback differs from negative feedback as it increases the original change and the role of oxytocin in birth and the movement of sodium ions into a neurone are used to exemplify the action of this control system.

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 engaging lesson describes how chromosome mutations result in changes to the number or structure of chromosomes The PowerPoint and accompanying resources are part of the second lesson in a series of 2 lessons that have been designed to cover specification points (f) in topic 3 of A2 unit 4 of the WJEC A-level Biology specification, and there is a key focus on Down syndrome A human karyotype which has not been altered by a mutation is studied at the start of the lesson to allow students to recall the usual number of chromosomes as well as the sex chromosomes. They are then challenged to identify the differences when presented with the karyotypes of sufferers of Down, Turner’s and Klinefelter’s syndrome. Students will learn that in the majority of cases, these conditions are the result of non-disjunction and having been assisted in the explanation of the outcome for Down and Klinefelters, they have to form their own for Turner’s. The remainder of the lesson looks at other types of mutations, including translocation, and students will also see how whole sets of chromosomes can be duplicated in polyploidy

This lesson describes the effects of pH on the rate of an enzyme-catalysed reaction. The PowerPoint and accompanying resources are part of the second lesson in a series of 4 lessons which have been designed to cover the content of point 3.2 (a) of the CIE A-level Biology specification. The lesson begins with a short discussion, where the students are challenged to identify how the stomach and the small intestine differ in terms of a particular condition and to explain why the conditions in these neighbouring digestive organs are so important. This introduces pepsin and trypsin and these protease enzymes play a key role throughout the lesson as they are good examples of how different extracellular enzymes have different optimum pH values (which are not necessarily 7.0). Moving forwards, students will discuss how the rate of an enzyme-controlled reaction will change if there are small or large changes in pH, and then time is taken to ensure that students can explain these changes with reference to tertiary structure bonds and the shape of the active site. Through the use of a quick quiz competition, the students will be reminded of the key term “buffer” and a series of questions are used to challenge their understanding of how these substances could be used in a practical investigation. They will also learn how buffers are found in blood plasma as well as in red blood cells in the form of haemoglobin. As there is a considerable proportion of marks for Maths in a Biology context questions in the A-level assessments, the remainder of the lesson challenges the students to use a given formula to calculate the pH of blood when given the hydrogen ion concentration and to calculate percentage decrease. These questions have been differentiated to give assistance to those that need the support

This lesson guides students through the use of a chi-squared test to determine the significance of the difference between observed and expected results. It is fully-resourced with a detailed PowerPoint and differentiated worksheets that have been designed to cover point (d) in topic 3 of A2 unit 4 of the WJEC A-level Biology specification The lesson includes a step-by-step guide to demonstrates how to carry out the test in small chunks. At each step, time is taken to explain any parts which could cause confusion and helpful hints are provided to increase the likelihood of success in exam questions on this topic. Students will understand how to use the phenotypic ratio to calculate the expected numbers and then how to find the critical value in order to compare it against the chi-squared value. A worked example is used to show the working which will be required to access the marks and then the main task challenges the students to apply their knowledge to a series of questions of increasing difficulty. This lesson has been specifically designed to tie in with the previous lessons in this topic as there are regular references to dihybrid inheritance as well as to topics in the AS units like meiosis

This lesson introduces and explains the meaning of 11 key terms associated with the genetic inheritance topic. The PowerPoint and accompanying resources have been designed to cover point 6.1.6 of the AQA GCSE Combined Science specification and include explanations of genome, chromosome, gene, allele, genotype, homozygous, heterozygous, phenotype, dominant, recessive and gamete. The key term, genome, was met earlier in topic 6 so the lesson begins with a knowledge retrieval with the definition for this term. As the genome is the entire DNA of an organism, the next task challenges the students to identify three errors in a passage about DNA. This challenges their recall of the structure of this chemical as a double helix, its location in an eukaryotic cell in the nucleus and an understanding that the gene codes for the sequence of amino acids in a specific protein. This leads into discussions about chromosomes and genes and time is taken to explain that homologous chromosomes have the same genes at the exact same gene loci. The students will learn that alternative forms of the gene (alleles) can be found at these loci and that these structures explain the differences in inherited characteristics. Moving forwards, the main section of the lesson describes the link between the dominant and recessive alleles, homozygous and heterozygous genotypes, and the physical expression as the phenotype. The final key term is gamete, and the students are challenged to recognise a definition for this term using their knowledge of meiosis. Two progress and understanding checks complete the lesson and check on the students’ ability to recognise and write definitions for these 11 terms and to use them accurately in a written description

This lesson describes how the alveoli are adapted for gas exchange by diffusion between the air in the lungs and the blood capillaries. The PowerPoint and accompanying resource are part of the second lesson in a series of 2 which have been designed to cover the content of point 8.2 & 8.3 of the Edexcel GCSE Biology and Combined Science specifications. During the 1st lesson in this series, the students were shown how to calculate the surface area to volume ratio and so this lesson begins by challenging them to recall that the larger the organism, the smaller the ratio. This is done through the PLAY YOUR CARDS RIGHT format as shown in the cover picture, and leads into the key idea that complex multicellular organisms like humans have developed a range of different adaptations to increase this ratio at their exchange surfaces. Moving forwards, time is taken to consider and discuss how the following adaptations of the alveoli affect the rate of diffusion: large surface area lining of the alveoli consisting of a single layer of flattened cells maintenance of a steep concentration gradient Each feature is related to diffusion and current understanding and prior knowledge checks are used to allow the students to assess their progress and to challenge them to make links to other topics of the course. All exam questions have mark schemes embedded into the PowerPoint

This revision lesson provides students with the opportunity to assess their understanding of nucleic acids and protein synthesis (topic 6). The lesson includes a multiple-choice assessment of 10 questions and a PowerPoint containing the answers, where each answer slide shows the exact specification code to enable students to note the areas which may require extra attention. The PowerPoint also contains additional questions to challenge content from topic 6 of the CIE A-level biology specification (2025 - 2027 update) that isn’t directly covered by the 10 questions, and prior knowledge checks to encourage students to make links to content from topics 1 - 5. This lesson has been designed to be used at the end of topic 6, and in the build up to mocks and the final A-level assessments.

This revision lesson provides students with the opportunity to assess their understanding of homeostasis (topic 14). The lesson includes a multiple-choice assessment of 10 questions and a PowerPoint containing the answers, where each answer slide shows the exact specification code to enable students to note the areas which may require extra attention. The PowerPoint also contains additional questions to challenge content from topic 14 of the CIE A-level biology specification (2025 - 2027 update) that isn’t directly covered by the 10 questions, and prior knowledge checks to encourage students to make links to content from any of topics 1 - 13.

This revision lesson uses a multiple-choice assessment to challenge the students on their understanding of topic 8, the control of gene expression. In addition to the 20 question assessment, this lesson includes a PowerPoint where the answers are revealed and additional questions are posed about the content of topic 8 which isn’t directly challenged in the questions. The PowerPoint also contains prior knowledge checks on content from topics 1, 3, 4 and 6. Revision lessons of this format which challenge topics 1 - 7 are also uploaded.

This lesson describes how the loop of Henle acts as a countercurrent multiplier to increase the reabsorption of water. The PowerPoint and accompanying resources are part of the 2nd lesson in a series of 2 lessons which have been designed to cover point 7.20 of the Edexcel International A-level biology specification. The lesson begins by challenging the students to recognise that the glomerular filtrate entering the loop will only contain water, ions and urea if the kidneys are functioning properly. Time is then taken to look at the structure of the loop of Henle, focusing on the descending and ascending limbs, and their differing permeabilities. Students will be reminded that this part of the nephron is located in the renal medulla, before a step-by-step guide is used to describe how the transfer of ions, particularly sodium ions, from the ascending limb to the descending limb, creates a very negative water potential in this region of the kidney. This allows water to move out of the descending limb to the tissue fluid and then into the capillaries. The next task has been designed to challenge the students on their knowledge of the numbers associated with biology to reveal the key term, countercurrent. They will learn that the countercurrent flow principle involves fluids flowing in opposite directions past each other and an example in bony fish is used to increase the relevance, before they understand how this multiplier works in the loop to increase water reabsorption. The next part of the lesson challenges students to consider the bigger picture as they learn that this decreasing water potential in the medulla allows water to be reabsorbed from the filtrate in the collecting duct too. The remainder of the lesson uses the real-world examples of the hopping mouse and kangaroo rat to check student understanding, and there are also prior knowledge checks to encourage students to make links to relevant content from earlier topics. All answers are embedded into the PowerPoint.

This lesson focuses on the structure of the spinal cord but also introduces key nervous system structures to prepare students for upcoming topic 9 lessons. The PowerPoint and accompanying resource have been planned to cover the content of point 9.4 (ii) of the Edexcel A-level biology B specification. As shown on the cover image, the lesson begins with a challenge, where students must use their knowledge of content from earlier topics to reveal 5 numbers that add up to 33. They will learn that this is the normal number of vertebrae in the human vertebral column and this leads into the recognition that these bones act to surround and protect the spinal cord. The meninges are introduced and then a quick quiz round is used to reveal the term, grey matter. Students will see that this is found in the centre of the spinal cord and is surrounded by an outer region of white matter. The idea of myelination is introduced, and initial details provided about the increased conductance speed in myelinated neurones because of saltatory conduction. Moving forwards, students will meet the terms dorsal and ventral and see on a diagram that nerves enter and leave the cord by these roots. The role of cerebrospinal fluid is explored and a series of exam-style questions are used to challenge their knowledge from topic 2 and 6 as well as their mathematical skills. The answers are embedded into the PowerPoint to allow the students to assess their progress. The lesson finishes with the introduction of the cauda equina as the bundle of nerves at the distal end of the spinal cord.