This lesson describes and explains how increasing the temperature affects the rate of an enzyme-controlled reaction. The PowerPoint and the accompanying resource have been designed to cover the second part of point 1.4.2 of the AQA A-level Biology specification and ties in directly with the previous lesson on the properties of enzymes and their mechanism of action. The lesson begins by challenging the students to recognise optimum as a key term from its 6 synonyms that are shown on the board. Time is taken to ensure that the students understand that the optimum temperature is the temperature at which the most enzyme-product complexes are produced per second and therefore the temperature at which the rate of an enzyme-controlled reaction works at its maximum. The optimum temperatures of DNA polymerase in humans and in a thermophilic bacteria and RUBISCO in a tomato plant are used to demonstrate how different enzymes have different optimum temperatures and the roles of the latter two in the PCR and photosynthesis are briefly described to prepare students for these future lessons. Moving forwards, the rest of the lesson focuses on enzyme activity at temperatures below the optimum and at temperatures above the optimum. Students will understand that increasing the temperature increases the kinetic energy of the enzyme and substrate molecules, and this increases the likelihood of successful collisions and the production of enzyme-substrate and enzyme-product complexes. When considering the effect of increasing the temperature above the optimum, continual references are made to the previous lesson and the control of the shape of the active site by the tertiary structure. Students will be able to describe how the hydrogen and ionic bonds in the tertiary structure are broken by the vibrations associated with higher temperatures and result in an active site that is no longer complementary to the substrate. Key terminology such as denaturation is used throughout. Please note that this lesson has been designed specifically to explain the relationship between the change in temperature and the rate of reaction and not the practical skills that would be covered in a core practical lesson

This fully-resourced lesson explains how an enzyme’s specificity is related to their 3D structure and enables them to act as biological catalysts. The engaging PowerPoint and accompanying resources have been designed to cover the first parts of specification point 1.4.2 and considers the details of Fischer’s lock and key hypothesis and Koshland’s induced-fit model to deepen student understanding of the mechanism of enzyme action The lesson has been specifically planned to tie in with related topics that were previously covered such as protein structure and globular proteins. This prior knowledge is tested through a series of exam-style questions along with current understanding and mark schemes are included in the PowerPoint so that students can assess their answers. Students will learn that enzymes are large globular proteins which contain an active site that consists of a small number of amino acids. Emil Fischer’s lock and key hypothesis is introduced to enable students to recognise that their specificity is the result of an active site that is complementary in shape to a single type of substrate. Time is taken to discuss key details such as the control of the shape of the active site by the tertiary structure of the protein. The induced-fit model is described so students can understand how the enzyme-susbtrate complex is stabilised and then students are challenged to order the sequence of events in an enzyme-controlled reaction. The lesson finishes with a focus on ATP synthase and DNA polymerase so that students are aware of these important intracellular enzymes when learning about the details of respiration and DNA replication before they are challenged on their knowledge of carbohydrates, lipids and proteins from topics 1.2 - 1.4 as they have to recognise some extracellular digestive enzymes.

This engaging lesson describes how the structure of the mammalian lung is adapted for rapid gaseous exchange. The PowerPoint has been designed to cover point 2.1 (iii) of the Pearson Edexcel A-level Biology A specification and focuses on the essential features of the alveolar epithelium as well as the mechanism of ventilation to maintain a steep concentration gradient for the simple diffusion of oxygen and carbon dioxide. Gas exchange at the alveoli is a topic that was covered at GCSE and considered during the previous lessons in topic 2.1 so this lesson has been written to challenge the recall of that knowledge and then to build on it. The main focus of the first half of the lesson is the type of epithelium found lining the alveoli and students will discover that a single layer of flattened cells known as simple, squamous epithelium acts to reduce the diffusion distance. The following features of the alveolar epithelium are also covered: Surface area Moist lining Production of surfactant The maintenance of a steep concentration gradient is the role of the respiratory system and the next part of the lesson focuses on the diaphragm and intercostal muscles. As the mechanism of inhalation is a cascade of events, the details of this process are covered in a step by step format using bullet points. At each step, time is taken to discuss the key details which includes an introduction to Boyle’s law that reveals the inverse relationship between volume and pressure. It is crucial that students are able to describe how the actions of the diaphragm, external intercostal muscles and ribcage result in an increased volume of the thoracic cavity and a subsequent decrease in the pressure, which is below the pressure outside of the body. At this point, their recall of the structures of the mammalian gas exchange system is tested, to ensure that they can describe the pathway taken by air when moving into the lungs.

This fully-resourced lesson describes the action of enzymes as biological catalysts and explains how their specificity is related to their 3D structure. The engaging PowerPoint and accompanying resources have been designed to cover points 2.10 (i) and (ii) of the Pearson Edexcel A-level Biology A specification but also introduces some examples of intracellular and extracellular enzymes to prepare students for the next lesson which covers 2.10 (iii). The lesson has been specifically planned to tie in with related topics that were previously covered such as protein structure, globular proteins and intracellular enzymes. This prior knowledge is tested through a series of exam-style questions along with current understanding and mark schemes are included in the PowerPoint so that students can assess their answers. Students will learn that enzymes are large globular proteins which contain an active site that consists of a small number of amino acids. Emil Fischer’s lock and key hypothesis is introduced to enable students to recognise that their specificity is the result of an active site that is complementary in shape to a single type of substrate. Time is taken to discuss key details such as the control of the shape of the active site by the tertiary structure of the protein. The induced-fit model is described so students can understand how the enzyme-susbtrate complex is stabilised and then students are challenged to order the sequence of events in an enzyme-controlled reaction. The lesson finishes with a focus on ATP synthase and DNA polymerase so that students are aware of these important intracellular enzymes when learning about the details of respiration and DNA replication.

This fully-resourced lesson describes how the cohesion-tension model explains the transport of water from the roots to the shoots. The detailed PowerPoint and accompanying resources have been designed to cover point 4.7 (iii) of the Edexcel A-level Biology B specification This lesson has been written to follow on from the end of the previous lesson, which finished with the description of the transport of the water and mineral ions from the endodermis to the xylem. Students are immediately challenged to use this knowledge to understand root pressure and the movement by mass flow down the pressure gradient. Moving forwards, time is taken to study the details of transpiration pull and then the main focus is the interaction between cohesion and tension. The role of adhesive forces in capillary action is also explained. Understanding is constantly checked through a range of tasks and prior knowledge checks are also written into the lesson to challenge the students to make links to previously covered topics such as the structure of the transport tissues.

This detailed lesson describes how water can be moved through plant cells by the apoplastic and symplastic pathways. The engaging PowerPoint and accompanying resource have been designed to cover point 4.7 (ii) of the Edexcel A-level Biology B specification and includes a description of the movement from the endodermis to the xylem to tie in with the following lesson on the cohesion-tension model. The lesson begins by looking at the specialised features of the root hair cell to allow students to understand how these epidermal cells absorb water and mineral ions from the soil. Moving forwards, students are introduced to key terminology such as epidermis and root cortex before time is taken to look at the different pathways that water and minerals use to transverse across the cortex. Discussion points are included throughout the lesson to encourage the students to think about each topic in depth and challenges them to think about important questions such as why the apoplastic pathway is needed for the water carrying the ions. Students will be introduced to the Casparian strip and will learn how this layer of cells blocks the apoplastic pathway. A step by step method using class questions and considered answers is used to guide them through the different steps and to support them when writing the detailed description.

This lesson describes the relationship between the structure and function of the xylem and phloem in transport. The engaging and detailed PowerPoint and accompanying resources have been designed to cover point 4.7 (i) of the Edexcel A-level Biology B specification. The lessons begins by challenging the students to identify the substances that a plant needs for the cellular reactions, where they are absorbed and where these reactions occur in a plant. The aim of this task is to get the students to recognise that water and mineral ions are absorbed in the roots and needed in the leaves whilst the products of photosynthesis are in the leaves and need to be used all over the plant. Students will be reminded that the xylem and phloem are part of the vascular system responsible for transporting these substances and then the rest of the lesson focuses on linking structure to function. A range of tasks which include discussion points, exam-style questions and quick quiz rounds are used to describe how lignification results in the xylem as a hollow tube of xylem cells to allow water to move as a complete column. They will also learn that the narrow diameter of this vessel allows capillary action to move water molecules up the sides of the vessel. The same process is used to enable students to understand how the structures of the companion cells allows assimilates to be loaded before being moved to the sieve tube elements through the plasmodesmata.

This lesson describes how an increased carbon dioxide concentration affects the dissociation of oxyhaemoglobin, the Bohr effect. The PowerPoint and accompanying resources have been designed to cover the second part of point 4.5 (i) of the Edexcel A-level Biology B specification and continually ties in with the previous lesson on the role of haemoglobin and dissociation curves. The lesson begins with a terminology check to ensure that the students can use the terms affinity, oxyhaemoglobin and dissociation. In line with this, they are challenged to draw the oxyhaemoglobin dissociation curve and are reminded that this shows how oxygen associates with haemoglobin but how it dissociates at low partial pressures. Moving forwards, 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. Opportunities are taken at this point to challenge students on their prior knowledge of protein structures as well as the bonds in the tertiary structure. 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 detailed lesson describes the role of haemoglobin in the transport of respiratory gases and compares the dissociation curves for foetal and adult haemoglobin. The PowerPoint and accompanying resource have been designed to cover points 4.5 (i), (ii) and (iv) of the Edexcel A-level Biology B specification. The structure of haemoglobin was covered during topic 1, so the start of the lesson acts as a prior knowledge check where the students are challenged to recall that it is a globular protein which consists of 4 polypeptide chains. A series of exam-style questions are then used to challenge them to make the link between the solubility of a globular protein and its role in the transport of oxygen from the alveoli to the respiring cells. Moving forwards, the students 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. 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. The remainder of the lesson looks at the different ways that carbon dioxide is transported around the body that involve haemoglobin. Time is taken to look at the dissociation of carbonic acid into hydrogen ions so that students can understand how this will affect the affinity of haemoglobin for oxygen in an upcoming lesson on the Bohr effect.

This fully-resourced lesson describes the roles of the platelets and plasma proteins in the sequence of events that lead to blood clotting. The engaging PowerPoint and accompanying resources have been primarily designed to cover the content detailed in point 4.4 (viii) of the Edexcel A-level Biology B specification and includes descriptions of the roles of thromboplastin, thrombin and fibrin but time has also been taken to look at haemophilia as a sex-linked disease so that students are prepared for topic 8 (genetic variation). The lesson begins with the introduction of clotting factors as integral parts of the blood clotting process and explains that factor III, thromboplastin, needs to be recalled as well as the events that immediately precede and follows its release. Students will learn how damage to the lining and the exposure of collagen triggers the release of this factor and how a cascade of events then results. Quick quiz rounds and tasks are used to introduce the names of the other substances involved which are prothrombin, thrombin, fibrinogen and fibrin. In a link to the upcoming topic of proteins, students will understand how the insolubility of fibrin enables this mesh of fibres to trap platelets and red blood cells and to form the permanent clot. The final part of the lesson introduces haemophilia as a sex-linked disease and students are challenged to apply their knowledge to an unfamiliar situation as they have to write genotypes and determine phenotypes before explaining why men are more likely to suffer from this disease than women.

This engaging lesson describes the myogenic stimulation of the heart and focuses on the roles of the SAN, AVN and bundle of His. The PowerPoint and accompanying resources have been designed to cover the point 4.4 (iv) of the Edexcel A-level Biology B specification but also describes the role of the Purkyne fibres. The lesson begins with the introduction of the SAN as the natural pacemaker and then time is given to study each step of the conduction of the impulse as it spreads away from the myogenic tissue in a wave of excitation. The lesson has been written to make clear links to the cardiac cycle and the structure of the heart and students are challenged on their knowledge of this system from earlier in the topic. Moving forwards, students are encouraged to consider why a delay would occur at the AVN and then they will learn that the impulse is conducted along the Bundle of His to the apex so that the contraction of the ventricles can happen from the bottom upwards. The structure of the cardiac muscle cells is discussed and the final task of the lesson challenges the students to describe the conducting tissue, with an emphasis on the use of key terminology.

This detailed lesson describes the pressure changes that occur during the cardiac cycle and explains how ECG traces can be interpreted. The PowerPoint and accompanying resources have been designed to cover points 4.4 (iii) & (v) of the Edexcel A-level Biology B specification and focuses on the importance of the valves in ensuring unidirectional movement of blood during the cycle. 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. The remainder of the lesson focuses on the ECG and explains how these traces can be interpreted to diagnose heart problems. A quiz competition is used to introduce the reference points of P, QRS and T on a normal sinus rhythm before time is taken to explain their representation with reference to the cardiac cycle. Moving forwards, a SPOT the DIFFERENCE task is used to challenge the students to recognise differences between sinus rhythm and some abnormal rhythms including tachycardia and atrial fibrillation. Bradycardia is used as a symptom of sinus node disfunction and the students are encouraged to discuss this symptom along with some others to try to diagnose this health problem.

This fully-resourced lesson describes the advantages of the double circulatory system that is found in mammals. The engaging PowerPoint and accompanying resources have been designed to cover point 4.4 (ii) of the Edexcel A-level Biology B specification and focuses on the differences in pressure between the pulmonary and systemic circulation. The lesson begins with a focus on the meaning of a double circulatory system and checks that students are clear in the understanding that the blood passes through the heart twice per cycle of the body. Beginning with the pulmonary circulation, students will recall that the pulmonary artery carries the blood from the right ventricle to the lungs. An opportunity is taken at this point to check on their knowledge of inhalation and the respiratory system as well as the gas exchange between the alveoli and the capillary bed. A quick quiz is used to introduce arterioles and students will learn that these blood vessels play a crucial role in the changes in blood pressure that prevent the capillaries from damage. When looking at the systemic circulation, time is taken to look at the coronary arteries and renal artery as students have to be aware of these vessels in addition to the ones associated with the heart. In the final part of the lesson, students are challenged to explain how the structure of the heart generates a higher pressure in the systemic circulation and then to explain why the differing pressures are necessary.

This fully-resourced lesson describes the relationship between the structure and the function of the heart, arteries, veins and capillaries. The engaging and detailed PowerPoint and accompanying resources have been designed to cover point 4.1 (i) as detailed in the Edexcel A-level Biology Bspecification. The structure of the heart is a topic which was covered in part at GCSE so this lesson has been written to build on that prior knowledge. The main task of the first half of the lesson involves students labelling the different structures as they are recalled. Time is taken at appropriate points to look at some of the structures and concepts in further detail. For example, students will learn that humans have a double circulatory system, which will prepare them for the next lesson, and are challenged to explain why a hole in the septum would cause health issues for an affected individual By the end of the first part of the lesson, the students will be able to identify the following structures and describe their individual functions: • right and left atria • right and left ventricles • septum • tricuspid and bicuspid valve • semi-lunar valves • pulmonary artery and pulmonary vein • vena cava • aorta Moving forwards, the lesson focuses on the link between the structure of a particular type of blood vessel and its function. 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 in excess of 2 hours of allocated A-level Biology teaching time to cover the detail included in this lesson

This lesson describes how the hydrolysis of ATP provides energy for biological processes such as active transport and endocytosis and exocytosis. The PowerPoint and accompanying resources have been designed to cover points 4.2 (iv), (v) & (vi) of the Edexcel A-level Biology B specification The start of the lesson focuses on the structure of this energy currency and challenges the students to use their knowledge of nucleotides and specifically RNA nucleotides to recognise the components of ATP. As a result, they will learn that this molecule consists of adenine, ribose and three phosphate groups. In order to release the stored energy, ATP must be broken down and students will be given time to discuss which reaction will be involved as well as the products of this reaction. Time is taken to describe how the hydrolysis of ATP can be coupled to energy-requiring reactions and this leads into a series of exam-style questions where students are challenged on their knowledge of simple and facilitated diffusion to recognise that ATP is needed for active transport. These questions also challenge them to compare active transport against the forms of passive transport and to use data from a bar chart to support this form of transport. In answering these questions they will discover that carrier proteins are specific to certain molecules and time is taken to look at the exact mechanism of these transmembrane proteins. A quick quiz round introduces endocytosis and the students will see how vesicles are involved along with the energy source of ATP to move large substances in or out of the cell. The lesson concludes with a link to a future topic as the students are shown how exocytosis is involved in a synapse and in the release of ADH from the pituitary gland during osmoregulation.

This detailed and engaging lesson describes how the passive transport of water molecules is brought about by osmosis. The PowerPoint and accompanying resources have been designed to cover the second part of specification point 4.2 (ii) as detailed in the Edexcel A-level Biology B specification and water potential is included throughout which will help students to prepare for core practical 6 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 between cells and a solution when these animal and plant cells are suspended in hypotonic, hypertonic or isotonic solutions.

This lesson describes how passive transport is brought about (simple) diffusion and facilitated diffusion. The PowerPoint and accompanying resources have been designed to cover the first part of specification point 4.2 (ii) of the Edexcel A-level Biology B specification but also covers 4.2 (iii) as the relationship between the properties of a molecule and the method by which they are transported is discussed. The structure of the cell surface membrane was described in the previous lesson, so this lesson has been written to include continual references to the content of that lesson. This enables links to be made between the movement across a cell membrane with the concentration gradient, the parts of the membrane that are involved and any features that may increase the rate at which the molecules move. A series of questions about the alveoli are used to demonstrate how a large surface area, a short diffusion distance and the maintenance of a steep concentration gradient will increase the rate of simple diffusion. One of two quick quiz rounds is then used to introduce temperature and size of molecule as two further factors that can affect simple diffusion. The remainder of the lesson focuses on facilitated diffusion and describes how transmembrane proteins are needed to move small, polar or large molecules from a high concentration to a lower concentration across a partially permeable membrane