This fully-resourced lesson describes the process of skeletal muscle contraction in terms of the sliding filament theory. The engaging and detailed PowerPoint and accompanying resources have been designed to cover point 7.2 of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification and includes the role of actin, myosin, troponin, tropomyosin, calcium ions and ATP. The lesson begins with a study of the structure of the thick and thin filaments. Students will recognise that the protruding heads of the myosin molecule are mobile and this enables this protein to bind to the binding sites when they are exposed on actin. This leads into the introduction of troponin and tropomyosin and key details about the binding of calcium to this complex is explained. Moving forwards, students are encouraged to discuss possible reasons that can explain how the sarcomere narrows during contraction when the filaments remain the same length. This main part of the lesson goes through the main steps of the sliding filament model of muscle contraction and the critical roles of the calcium ions and ATP are discussed. The final task of the lesson challenges the students to apply their knowledge by describing the immediate effect on muscle contraction when one of the elements doesn’t function correctly. This lesson has been written to tie in with another uploaded lesson on the structure of a muscle fibre which is covered in specification point 7.10

This fully-resourced lesson explores how the structure of arteries, veins and capillaries relates to their functions. The engaging and detailed PowerPoint and accompanying resources have been designed to cover point 1.3 of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification. This lesson has been written to build on any prior knowledge from GCSE or earlier in this topic to enable students to fully understand why a particular type of blood vessel has 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 the GUESS WHO game is used to introduce smooth muscle and collagen in the tunica media and externa and again the reason for their presence is explored and explained. Moving forwards, 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. The final part of the lesson looks at the role of the capillaries in exchange. 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. It is estimated that it will take about 2 hours of allocated A-level Biology teaching time to cover the detail included in this lesson

This engaging lesson looks at the structure of the quaternary protein, haemoglobin, and describes its role with red blood cells in the transport of oxygen. The PowerPoint has been designed to cover the first part of point 3.4.1 of the AQA A-level Biology specification and explains how the cooperative nature of binding results in a loading of each molecule with 4 oxygen molecules and describes how it is unloaded at the respiring cells too. The lesson begins with a version of the quiz show Pointless to introduce haemotology as the study of the blood conditions. Students are told that haemoglobin has a quaternary structure and are challenged to use their prior knowledge of biological molecules to determine what this means for the protein. They will learn that each of the 4 polypeptide chains contains 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. Students will learn that a conformational change upon binding of the first oxygen leads to it being easier to bind future oxygens and that this is known as cooperative binding. This lesson has been written to tie in with the other uploaded lesson on the Bohr effect.

This fully-resourced lesson explains how gene mutations can occur by substitution, deletion and insertion and explores how these base pair changes can affect the primary structure of the polypeptide and therefore the phenotype. The engaging and detailed PowerPoint and accompanying resources have been designed to cover point 16.2 (e) of the CIE International A-level Biology specification which states that students should understand how these mutations occur and can affect the phenotype. In order to understand how a change in the base sequence can affect the order of the amino acids, students must be confident in their understanding and application of protein synthesis which was taught in topic 6. Therefore, the start of the lesson focuses on transcription and translation and students are guided through the use of the codon table to identify amino acids. Moving forwards, a quick quiz competition is used to introduce the names of three types of gene mutation whilst challenging the students to recognise terms which are associated with the genetic code and were met in the previous lesson. The main focus of the lesson is base substitutions and how these mutations may or may not cause a change to the amino acid sequence. The students are challenged to use their knowledge of the degenerate nature of the genetic code to explain how a silent mutation can result. The rest of the lesson looks at base deletions and base insertions and students are introduced to the idea of a frameshift mutation. One particular task challenges the students to evaluate the statement that base deletions have a bigger impact on primary structure than base substitutions. This is a differentiated task and they have to compare the fact that the reading frame is shifted by a deletion against the change in a single base by a substitution

This engaging and fully-resourced lesson looks at how genetic drift can arise after a genetic bottleneck or as a result of the Founder effect. The detailed PowerPoint and accompanying resources have been designed to cover point 17.2 © of the CIE International A-level Biology specification which states that students should be able to explain how the Founder effect and genetic drift may affect allele frequencies in populations. A wide range of examples are used to show the students how a population that descends from a small number of parents will have a reduction in genetic variation and a change in the frequency of existing alleles. Students are encouraged to discuss new information to consider key points and understanding checks in a range of forms are used to enable them to check their progress and address any misconceptions. Students are provided with three articles on Huntington’s disease in South Africa, the Caribbean lizards and the plains bison to understand how either a sharp reduction in numbers of a new population beginning from a handful of individuals results in a small gene pool. Links to related topics are made throughout the lesson to ensure that a deep understanding is gained.

This fully-resourced lesson guides students through the use of the Hardy-Weinberg equations to determine the frequency of alleles, genotypes and phenotypes in a population. Both the detailed PowerPoint and differentiated practice questions on a worksheet have been designed to cover point 17.2 (d) of the CIE International A-level Biology specification which states that students should be able to demonstrate and apply their knowledge and understanding of the use of the principle to calculate frequencies in populations. The lesson begins by looking at the two equations and ensuring that students understand the meaning of each of the terms. The recessive condition, cystic fibrosis, is used as an example so that students can start to apply their knowledge and assess whether they understand which genotypes go with which term. Moving forwards, a step-by-step guide is used to show students how to answer a question. Tips are given during the guide so that common misconceptions and mistakes are addressed immediately. The rest of the lesson gives students the opportunity to apply their knowledge to a set of 3 questions, which have been differentiated so that all abilities are able to access the work and be challenged.

This engaging and fully-resourced lesson looks at the effects of stabilising, directional and disruptive selection as the three main types of selection. The PowerPoint and accompanying resources have been designed to cover point 17.2 (b) of the CIE International A-level Biology specification which states that students should be able to identify each type of selection by its effect on different phenotypes. The lesson begins with an introduction to the mark, release, recapture method to calculate numbers of rabbits with different coloured fur in a particular habitat. This method is covered later in topic 18 so this section of the lesson is designed purely to generate changes in numbers of the organisms. Sketch graphs are then constructed to show the changes in the population size in this example. A quick quiz competition is used to engage the students whilst introducing the names of the three main types of selection before a class discussion point encourages the students to recognise which specific type of selection is represented by the rabbits. Key terminology including intermediate and extreme phenotypes and selection pressure are used to emphasise their importance during explanations. A change in the environment of the habitat and a change in the numbers of the rabbits introduces directional selection before students will be given time to discuss and to predict the shape of the sketch graph for disruptive selection. Students are challenged to apply their knowledge in the final task of the lesson by choosing the correct type of selection when presented with details of a population and answer related questions.

This fully-resourced lesson looks at the external and internal structure of the mammalian heart and explains how the differences in the thickness of the chamber walls is related to function. The engaging and detailed PowerPoint and accompanying resources have been designed to cover points 8.2 (a) and (b) of the CIE International A-level Biology specification 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. As detailed in specification point (b), time is taken to ensure that students can explain why the atrial walls are thinner than the ventricle 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 topics 8.1 and 8.2 including those which have already been covered like circulatory systems as well as those which are upcoming such as the cardiac cycle. 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.

This fully-resourced lesson looks at the internal and external structure of the mammalian heart and uses the human heart to represent this anatomy. The engaging and detailed PowerPoint and accompanying resources have been designed to cover point 3.1.2 (e) (i) of the OCR A-level Biology A specification 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 3.1.2 including those which have already been covered like circulatory systems as well as those which are upcoming such as the initiation of heart action. 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.

This detailed and fully-resourced lesson describes and explains the pressure changes in the heart and arteries and the role of the valves movements in the cardiac cycle. The PowerPoint and accompanying resources have been designed to cover point 3.1.2 (f) of the OCR A-level Biology A specification and also covers the use of the equation stroke volume x heart rate to calculate cardiac output The start of the lesson introduces the cardiac cycle as well as the key term systole, so that students can immediately recognise that the three stages of the cycle are atrial and ventricular systole followed by diastole. Students are challenged on their prior knowledge of the structure of the heart as they have to name and state the function of an atrioventricular and semi-lunar valve from an internal diagram. This leads into the key point that pressure changes in the chambers and the major arteries results in 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 next part 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. 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 to calculate the percentage change which is a commonly assessed mathematical skill. This lesson has been written to tie in with the other uploaded lessons on the topics detailed in module 3.1.2 (Transport in animals)

This fully-resourced REVISION lesson has been written to challenge the students on their knowledge of the content of topic 1 (Cell structure) of the CIE International A-level Biology specification. The PowerPoint and accompanying resources will motivate the students whilst they assess their understanding of the content and identify any areas which may require further attention. The wide range of activities have been written to cover as much of the topic as possible but the following specification points have been given particular focus: ATP is produced in mitochondria and chloroplasts and the role of ATP in cells Recognising eukaryotic cell structures and outlining their functions Calculating actual sizes from electron micrographs The structural features of a typical prokaryotic cell The key features of viruses as non-cellular structures Distinguish between resolution and magnification Quiz rounds such as “GUESS WHO of CELL STRUCTURES” and “YOU DO THE MATH” are used to test the students on the finer details of their knowledge of the structure and functions of the organelles and some key numerical facts

This fully-resourced REVISION lesson has been written to challenge the students on their knowledge of the content of topic 8 (Transport in mammals) of the CIE International A-level Biology specification. The engaging PowerPoint and accompanying resources will motivate the students whilst they assess their understanding of the content and identify any areas which may require further attention. The wide range of activities have been written to cover as much of the topic as possible but the following specification points have been given particular focus: The significance of the oxygen dissociation curves at different concentrations of carbon dioxide (The Bohr effect) The role of haemoglobin in carrying oxygen The role of haemoglobin in carrying carbon dioxide Draw the structures of red blood cells, neutrophils, monocytes and lymphocytes The relationship between the structure and function of a capillary The internal structure of the heart and its associated blood vessels Explain how heart action is initiated and controlled The pressure changes of the cardiac cycle The relationship between the structure and function of arteries and veins The double, closed circulatory system of a mammal Quiz rounds such as “Does this FLOW correctly” and “YOU DO THE MATH” are used to test the students on the finer details of their knowledge of the blood vessels and numerical facts

This detailed lesson describes and explains the blood pressure changes that occur during systole and diastole of the cardiac cycle. The PowerPoint and accompanying resource have been designed to cover point 8.2 © of the CIE International A-level Biology specification. The start of the lesson introduces the cardiac cycle as well as the key term systole, so that students can immediately recognise that the three stages of the cycle are atrial and ventricular systole followed by diastole. Students are challenged on their prior knowledge of the structure of the heart as they have to name and state the function of an atrioventricular and semi-lunar valve from an internal diagram. This leads into the key point that pressure changes in the chambers and the major arteries results in 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. This lesson has been written to tie in with the other uploaded lessons on the heart as detailed in topic 8.2

This fully-resourced lesson looks at the cardiac cycle and relates the structure and operation of the mammalian heart to its function. The engaging and detailed PowerPoint and accompanying resources have been designed to cover point 1.4 (i) of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification As the structure of the heart 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 1 including those which have already been covered like circulatory systems as well as those which are upcoming such as the initiation of heart action. 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 as well as the key term systole, so that students can immediately recognise that the three stages of the cycle are atrial and ventricular systole followed by cardiac diastole. Students are challenged to name and state the function of an atrioventricular and semi-lunar valve from an internal diagram. This leads into the key point that pressure changes in the chambers and the major arteries results in 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