This lesson explains how labelled DNA probes in microarrays can be used to identify active genes. The PowerPoint and accompanying resources have been designed to cover the content of point 8.20 of the Edexcel International A-level biology specification. The lesson begins by introducing the BRCA genes, and the students will learn how faulty alleles of these two genes can increase an individual’s risk of developing breast cancer. Therefore, there is a need to be able to locate specific alleles like these, and this function is performed by DNA probes. The students are challenged to use the function of the probes to predict their structure and will understand that they are short lengths of single stranded DNA that have a base sequence complementary to the base sequence of part of the target allele. A quick quiz round is used to introduce hybridisation as a key term, to ensure that students recognise that the probe will bind if the complementary base sequence is encountered. Moving forwards, a DNA microarray is introduced to show that it’s possible to screen for multiple genes. The remainder of the lesson considers how the DNA probes are used to screen for heritable conditions and drug responses, and real-life examples are used to increase relevance.

This lesson explains how labelled DNA probes can be used to screen patients for heritable conditions, their responses to drugs and to identify health risks. The PowerPoint and accompanying resources have been designed to cover the content of point 8.4.2 of the AQA A-level biology specification. The lesson begins by introducing the BRCA genes, and the students will learn how faulty alleles of these two genes can increase an individual’s risk of developing breast cancer. Therefore, there is a need to be able to locate specific alleles like these, and this function is performed by DNA probes. The students are challenged to use the function of the probes to predict their structure and will understand that they are short lengths of single stranded DNA that have a base sequence complementary to the base sequence of part of the target allele. As shown in the cover image, a quick quiz round is used to introduce hybridisation as key term, to ensure that students recognise that the probe will bind if the complementary base sequence is encountered. Moving forwards, a DNA microarray is introduced to show that it’s possible to screen for multiple genes. The remainder of the lesson considers how the DNA probes are used to screen for heritable conditions and drug responses, and real-life examples are used to increase relevance. Prior knowledge checks are embedded throughout the lesson to encourage the students to make links to content from earlier topics including inheritance and genetic drift.

This lesson describes how the loop of Henle acts as a countercurrent multiplier to increase the reabsorption of water. The PowerPoint and accompanying resource are part of the 2nd lesson in a series of 2 lessons which have been designed to cover point 9.9 (iii) of the Edexcel A-level biology B specification but also considers the structure of the kidney in the kangaroo rat and therefore also covers point 9.9 (v). 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 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 describes the meaning of excretion, as well as the role of the liver, kidneys, lungs and the skin in the removal of carbon dioxide and urea. The engaging PowerPoint and accompanying resources have been designed to cover point 5.1.2 (a) of the OCR A-level Biology specification and also explains the importance of excretion for homeostasis. The lesson begins by reminding students that excretion is one of the 7 characteristics of living organisms, as introduced within MRS GREN when they were younger. An A-level worthy definition of excretion is then introduced, and time is taken to ensure that students recognise that substances must be products of metabolism to be deemed to be excreted. In line with this, the students are challenged to spot that urea and carbon dioxide need to be excreted whilst faeces is egested. Moving forwards, the role of the liver and then the kidneys in the excretion of urea are described. There is a focus on terminology, specifically prefixes and suffixes, to allow students to understand the meaning of deamination which occurs in the liver. The lesson doesn’t go into huge detail about this process and the subsequent ornithine cycle as these are both covered in an upcoming lesson about the functions of the liver. The transport of carbon dioxide is revisited and prior knowledge checks are used to allow the students to assess their recollection of hydrogen carbonate ions and carbaminohaemoglobin. All answers to these checks as well as any understanding checks are embedded into the PowerPoint. The final part of the lesson explores how the skin is involved in excretion and a link is made to the maintenance of internal conditions within narrow limits by homeostasis.

This lesson describes how an ever decreasing water potential is created in the renal medulla to enable water reabsorption in the loop of Henle and collecting duct. The PowerPoint and accompanying resource are part of the 4th lesson in a series of 5 lessons which have been designed to cover point 6.4.3 (Control of blood water potential) of the AQA 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 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 describes succession as the gradual, progressive changes in a ecosystem, moving from colonisation by the pioneer species to a climax community. The detailed PowerPoint and accompanying resources have been designed to cover point 6.3.1 (d) of the OCR A-level Biology specification, and therefore the lesson also describes deflected succession and the formation of a plagioclimax community. As shown in the cover image, the lesson uses a step by step guide to describe primary succession, introducing the different species at each stage, and explaining the vital roles they each perform. Time is taken to explain how the initial colonisation by algae and lichens as pioneer species is critical to form soil, which wasn’t previously present on the bare ground. The real-world example of Surtsey is used to increase relevance and students will hear about the changes that have occurred on this island over the last 67 years. Understanding checks are included at regular points to allow the students to assess their progress, and prior knowledge checks challenge them to recall content from earlier modules. Answers to all of the checks are embedded in the PowerPoint. The final part of the lesson considers how many ecosystems are prevented from reaching their climax community and this is known as deflected succession. Human influences are explored and again, real examples are used.

This lesson guides students through the stages of the nitrogen cycle, focusing on the vital roles performed by microorganisms in this cycle. The detailed PowerPoint and accompanying resources are part of the 1st lesson in a series of 3 lessons which have been planned to cover point 5.4 (nutrient cycles) of the AQA A-level biology specification. The lesson begins by challenging students to recall two monomers containing nitrogen that were met in topic 1, allowing them to recognise that this chemical element is a key component of nucleotides in DNA and amino acids, which are needed to synthesise proteins. Moving forwards, they will learn that despite the high % of nitrogen in the Earth’s atmosphere, it cannot be used directly by plants, and therefore plants need a supply of “fixed” nitrogen. A diagram is constantly updated and displayed as new information is introduced and this supports their understanding. The students will discover that microorganisms are involved in nitrogen fixation, decomposition and ammonification, nitrification, and denitrification. As each of these biological actions is introduced, time is spent considering key details and understanding checks are used to allow the students to assess their progress. There are also several prior knowledge checks, where students are encouraged to make links to content met in topics 1 - 4. Answers to all questions are embedded into the PowerPoint.

This lesson describes the pathway by which the translation of mRNA into proteins can be prevented by siRNA and miRNA molecules. The engaging and detailed PowerPoint and accompanying resources are part of the final lesson in a series of 4 lessons that cover the detail of point 8.2.2 of the AQA A-level biology specification. The lesson begins with an exisiting knowledge check, as the students are challenged to recognise the processes of DNA methylation and histone acetylation, before RNA interference is introduced as another way by which gene expression is controlled in eukaryotes. Moving forwards, a quick quiz round introduces small interfering RNA (siRNA) and students will learn how this double-stranded, non-coding RNA is normally just 21 base pairs long. A step by step guide then describes the action of siRNA in preventing translation, through the cutting of the target mRNA into fragments which are then degraded. Time is taken to consider the possible application of siRNA molecules in the treatment of HIV and then cystic fibrosis, and the latter involves a series of exam-style questions which challenge the students on their understanding of this topic as well as the recall of content from the other 7 AQA topics. The remainder of the lesson focuses on microRNA (miRNA) and students will understand how this molecule is produced and how its action differs to that of siRNA in mammalian cells.

This lesson describes how only part of a cell’s DNA is translated and explains how the potency of a stem cell determines its ability to specialise. The engaging and detailed PowerPoint and accompanying resources have been planned to cover all of the content in point 8.2.1 of the AQA A-level biology specification. The lesson begins by challenging the students to recall any existing knowledge of stem cells, to check that they remember that these cells differentiate, before the concept of cell potency is introduced to allow them to recognise that not all cells can differentiate into the same amount of cell types. A quick quiz is used to introduce pluripotency, unipotency, totipotency and multipotency before they are challenged to use their understanding of language to order these along the potency continuum. Beginning with totipotency, time is taken to go through details of each of these cell types, including where these cells are located. During the section of the lesson considering pluripotency, induced pluripotent stem cells are discussed and their potential for use in regenerative medicine is explored. Understanding checks through exam-based questions are embedded throughout the lesson (as well as the answers) to allow students to assess their current understanding and to address any gaps immediately. There are also prior knowledge checks so students can link to other topics from the specification and there is a maths in biology question so their mathematical skills are challenged in line with that element of the course.

This detailed lesson describes the processes of PCR and electrophoresis to allow students to understand how gene sequencing can be used. The engaging PowerPoint and accompanying resource have been planned to cover the content of point 7.1 of the Edexcel A-level biology B specification. The lesson begins by comparing the number of genes in the genome with the number of base pairs, to allow students to learn that the bases in the genes only accounts for about 1.5% of the genome. This challenges them to recall that most is non-coding DNA, and the importance and usefulness of these sections are explored during the lesson. Moving forward, a step-by-step guide describes the key steps in the polymerase chain reaction, and time is taken at each step to qualify the fine details such as the use of Taq polymerase instead of human DNA polymerase. The remainder of the lesson focuses on the various uses of these DNA samples once they’ve been amplified by the PCR. The steps of the electrophoresis process are described and students will see how DNA profiling can be used in forensic science to identify criminals and for paternity tests. Understanding and prior knowledge checks are found throughout the lesson, along with the answers, to allow students to assess their grasp of the current topic as well as their ability to identify the links with previously covered topics.

This fully-resourced lesson looks at the structures that make up the gross anatomy of the heart and also covers the calculation of cardiac ouput. The engaging and detailed PowerPoint and accompanying resources have been designed to cover the 4th part of point 3.4.1 of the AQA A-level Biology specification which states that students should be able to describe the gross structure of the human heart and be able to use the equation stroke volume x heart rate to calculate cardiac output. As this topic was covered at GCSE, 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 3.4.1 such as blood circulation and the cardiac cycle. Moving forwards, the students are introduced to the stroke volume and meet normative values for this and for resting heart rate. This will lead into the calculation for cardiac output and a series of questions are used to test their ability to apply this equation as well as percentage change.

A fully resourced revision lesson which uses a range of exam questions (with explained answers), quick tasks and quiz competitions to enable the students to assess their understanding of the topics found within module 4 (Biodiversity, evolution and disease) of the OCR A-level Biology specification. The topics tested within this lesson include: Communicable diseases, biodiversity, classification and evolution Student will enjoy the range of tasks and quiz rounds whilst crucially being able to recognise any areas which require further attention