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A Science teacher by trade, I've also been known to be found teaching Maths and PE! However, strange as it may seem, my real love is designing resources that can be used by other teachers to maximise the experience of the students. I am constantly thinking of new ways to engage a student with a topic and try to implement that in the design of the lessons.

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A Science teacher by trade, I've also been known to be found teaching Maths and PE! However, strange as it may seem, my real love is designing resources that can be used by other teachers to maximise the experience of the students. I am constantly thinking of new ways to engage a student with a topic and try to implement that in the design of the lessons.
Topics 1 & 2: Cell structure & Biological molecules (CIE A-level Biology)
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Topics 1 & 2: Cell structure & Biological molecules (CIE A-level Biology)

18 Resources
It’s no coincidence that cell structure and biological molecules find themselves as topics 1 and 2 of the CIE A-level Biology course, because a clear understanding of their content is absolutely critical to promote success with the 17 topics that follow. Hours and hours of intricate planning has gone into the 18 lessons included in this bundle to ensure that the detailed content is relevant and can be understood and that links are made to related sections of topics 3 - 19. The lesson PowerPoints and accompanying resources contain a wide range of activities that include: differentiated exam-style questions with clear mark schemes directed discussion points quiz competitions to introduce key terms and values current understanding and prior knowledge checks Due to the detail included in these lessons, it is estimated that it will take in excess of 2 months of allocated teaching time to cover the content of the resources A number of the resources have been shared for free so these can be downloaded in order to sample the quality of the lessons
Topic 3: Enzymes (CIE A-level Biology)
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Topic 3: Enzymes (CIE A-level Biology)

6 Resources
This lesson bundle contains 6 fully-resourced lessons which have been designed to engage and motivate the students whilst covering the detailed content of topic 3 (Enzymes) in the CIE A-level Biology specification. These globular proteins catalyse biological reactions throughout living organisms so a deep understanding of this topic is important for all of the other 18 topics in this course. The wide range of activities that are included within the lesson PowerPoints and accompanying resources will cover the following specification points: Enzymes are globular proteins that catalyse reactions The mode of action of enzymes The lock and key hypothesis and the induced-fit model The effect of temperature on the rate of an enzyme-catalysed reaction The effect of pH on the rate of an enzyme-catalysed reaction The effect of enzyme and substrate concentration on the rate of an enzyme-catalysed reaction The effect of inhibitor concentration on the rate of an enzyme-catalysed reaction The effect of competitive and non-competitive inhibitors on enzyme activity Immobilising an enzyme in alginate
Immobilising an enzyme (CIE A-level Biology)
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Immobilising an enzyme (CIE A-level Biology)

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This lesson describes how enzymes can be immobilised in calcium alginate and compares their activity against enzymes that are free in solution. The PowerPoint and the accompanying resources have been designed to cover point 3.2 (d) of the CIE A-level Biology specification. The lesson has been planned to challenge the students on their ability to apply knowledge to a potentially unfamiliar situation. A series of exam-style questions which include “suggest” and “describe and explain” questions are used throughout the lesson and these will allow the students to recognise the advantages and disadvantages of a particular method. Although the alginate method is the only one referenced in this specification point, the adsorption and covalent bonding methods are introduced and then briefly analysed to allow students to understand that a matrix doesn’t involve these bonds which could disrupt the active site. The remainder of the lesson introduces some actual examples of the use of immobilised enzymes with the aim of increasing the relevance. Please note that this lesson has been written to explain the effect of immobilisation on enzyme activity. The practical element of carrying out the investigation is described in a separate lesson.
Inhibitors & enzyme-catalysed reactions (CIE A-level Biology)
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Inhibitors & enzyme-catalysed reactions (CIE A-level Biology)

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This lesson describes and explains how increasing the concentration of inhibitors affects the rate of an enzyme-catalysed reaction. The PowerPoint and accompanying resource are the last in a series of 4 lessons which cover the content detailed in point 3.2 (a) of the CIE A-level Biology specification but this lesson also covers point 3.2 [c] as competitive and non-competitive inhibitors are introduced and their differing effects on enzyme activity described and explained. The lesson begins with a made up round of the quiz show POINTLESS called “Biology opposites” and this allows students to recognise that inhibition is the opposite of stimulation. This introduces inhibitors as substances that reduce the rate of a reaction and students are challenged to use their general knowledge of enzymes to identify that inhibitors prevent the formation of the enzyme-substrate complex. Moving forwards, a quick quiz competition generates the abbreviation EIC (representing enzyme-inhibitor complex) and this introduces competitive inhibitors as substances that occupy the active site. The students are asked to apply their knowledge to a new situation to work out that these inhibitors must have a similar shape to the enzyme’s substrate molecule. A series of exam-style questions are used throughout the lesson and at this point, the students are challenged to work out that an increase in the substrate concentration would reduce the effect of a fixed concentration of a reversible competitive inhibitor. The rest of the lesson focuses on non-competitive inhibitors and time is taken to ensure that key details such as the disruption of the tertiary structure is understood and biological examples are used to increase the relevance. Again, students will learn that increasing the concentration of the inhibitor results in a greater inhibition and a reduced rate of reaction but that increasing the substrate concentration cannot reduce the effect as was observed with competitive inhibitors.
Temperature & enzyme-catalysed reactions (CIE A-level Biology)
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Temperature & enzyme-catalysed reactions (CIE A-level Biology)

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This lesson describes and explains the effect of an increasing temperature on the rate of an enzyme-catalysed reaction. The PowerPoint and the accompanying resource are part of the 1st lesson in a series of 4 which cover the content detailed in point 3.2 (a) of the CIE A-level Biology specification and this lesson has been specifically planned to tie in with the lesson in 3.1 where the properties of enzymes and their mechanism of action were introduced. 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 lessons in topics 19 and 13. 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 are challenged to complete the graph to show how the rate of reaction decreases to 0 when the enzyme has denatured. 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
Action of enzymes (CIE A-level Biology)
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Action of enzymes (CIE A-level Biology)

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This fully-resourced lesson describes how enzymes function intracellularly and extracellularly and explains their mode of action. The engaging PowerPoint and accompanying resources have been designed to cover points 3.1 (a, b & c) and considers the details of Fischer’s lock and key hypothesis and Koshland’s induced-fit model and explains how an enzyme’s specificity is related to their 3D structure and enables them to act as biological catalysts. The lesson has been planned to tie in with topic 2.3, and to challenge the students on their knowledge of 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 from descriptions of their biological molecule substrates.
Competitive & non-competitive inhibitors (AQA A-level Biology)
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Competitive & non-competitive inhibitors (AQA A-level Biology)

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This lesson describes and explains how increasing the concentration of inhibitors affects the rate of an enzyme-controlled reaction. The PowerPoint and accompanying resource are the last in a series of 5 lessons which cover the content detailed in point 1.4.2 of the AQA A-level Biology specification and describes the effect of both competitive and non-competitive inhibitors. The lesson begins with a made up round of the quiz show POINTLESS called “Biology opposites” and this will get the students to recognise that inhibition is the opposite of stimulation. This introduces inhibitors as substances that reduce the rate of a reaction and students are challenged to use their general knowledge of enzymes to identify that inhibitors prevent the formation of the enzyme-substrate complex. Moving forwards, a quick quiz competition generates the abbreviation EIC (representing enzyme-inhibitor complex) and this introduces competitive inhibitors as substances that occupy the active site. The students are asked to apply their knowledge to a new situation to work out that these inhibitors have a similar shape to the enzyme’s substrate molecule. A series of exam-style questions are used throughout the lesson and at this point, the students are challenged to work out that an increase in the substrate concentration would reduce the effect of a fixed concentration of a reversible competitive inhibitor. The rest of the lesson focuses on non-competitive inhibitors and time is taken to ensure that key details such as the disruption of the tertiary structure is understood and biological examples are used to increase the relevance. Again, students will learn that increasing the concentration of the inhibitor results in a greater inhibition and a reduced rate of reaction but that increasing the substrate concentration cannot reduce the effect as was observed with competitive inhibitors.
Enzymes and temperature (AQA A-level Biology)
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Enzymes and temperature (AQA A-level Biology)

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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
Properties of enzymes (AQA A-level Biology)
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Properties of enzymes (AQA A-level Biology)

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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.
The mammalian lung & gas exchange (Pearson Edexcel A-level Biology A)
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The mammalian lung & gas exchange (Pearson Edexcel A-level Biology A)

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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.
Properties and action of enzymes (Pearson Edexcel A-level Biology A)
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Properties and action of enzymes (Pearson Edexcel A-level Biology A)

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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.
Topic 4.4: Circulation (Edexcel A-level Biology B)
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Topic 4.4: Circulation (Edexcel A-level Biology B)

5 Resources
The 5 lesson PowerPoints and multiple accompanying resources that are included in this bundle are highly-detailed and engaging. A wide variety of tasks, which include exam-style questions, differentiated tasks, discussion points and quiz competitions will check on the student understanding of the following specification points in topic 4.4 of the Edexcel A-level Biology B specification: The structure of the heart, arteries, veins and capillaries The advantages of a double circulatory system The sequence of events of the cardiac cycle The roles of the SAN, AVN and the bundle of His in the myogenic stimulation of the heart Interpreting ECG traces and pressure changes in the cardiac cycle The role of platelets and plasma proteins in the sequence of events leading to blood clotting The heart & blood vessels and the double circulatory system lesson have been uploaded for free so you can sample the quality of this bundle by downloading those
Topic 4.2: Cell transport mechanisms (Edexcel A-level Biology B)
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Topic 4.2: Cell transport mechanisms (Edexcel A-level Biology B)

4 Resources
This bundle of 4 fully-resourced lessons have been planned to include a wide variety of tasks which will engage and motivate the students whilst covering the following points as detailed in topic 4.2 of the Edexcel A-level Biology B specification: The structure of the cell surface membrane, with reference to the fluid mosaic model Passive transport is brought about by diffusion and facilitated diffusion Passive transport is brought about by osmosis The relationship between the properties of molecules and the method by which they are transported Large molecules can be transported in and out of cells by endocytosis and exocytosis The process of active transport and the role of ATP The phosphorylation of ADP and the hydrolysis of ATP If you would like to sample the quality of the lessons in this bundle, then download the ATP & active transport lesson as this has been shared for free
Topic 4: Exchange and transport (Edexcel A-level Biology B)
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Topic 4: Exchange and transport (Edexcel A-level Biology B)

18 Resources
The wide variety of tasks that are written into the 18 lesson PowerPoints and accompanying resources that are included in this lesson bundle will engage and motivate the students whilst covering the detailed content of topic 4 of the Edexcel A-level Biology B specification (Exchange and transport). The following specification points are covered by these lessons: Understand how the surface area to volume ratio affects the transport of molecules in living organisms Understand why organisms need a mass transport system and specialised gas exchange surfaces as they increase in size The structure of the cell surface membrane Passive transport is brought about by diffusion and facilitated diffusion Passive transport is brought about by osmosis Understand how the properties of molecules affects how they are transported Large molecules are transported in and out of cells by endocytosis and exocytosis The process of active transport The phosphorylation and hydrolysis of ATP Understand how insects, fish and mammals are adapted for gas exchange The structure of the heart, arteries, veins and capillaries The advantages of the double circulatory system The sequence of events of the cardiac cycle The myogenic stimulation of the heart Interpreting ECG traces The role of platelets and plasma proteins in the sequence of events leading to blood clotting The structure of haemoglobin in relation to its role in the transport of respiratory gases The Bohr effect The dissociation curve of haemoglobin The significance of the oxygen affinity of foetal haemoglobin The similarities and differences between the structure and function of haemoglobin and myoglobin The formation and reabsorption of tissue fluid Know that tissue fluid that is not reabsorbed is returned to the blood via the lymph The structure of the xylem and phloem in relation to their role in transport The movement of water by the apoplastic and symplastic pathways The cohesion-tension model Hours and hours has gone into the intricate planning of all of these lessons and the quality can be sampled by downloading the following lessons which have been uploaded for free: Surface area to volume ratio ATP, active transport, endocytosis and exocytosis Structure of the heart, arteries, veins and capillaries Double circulatory system Apoplastic and symplastic pathways
Cohesion-tension model (Edexcel A-level Biology B)
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Cohesion-tension model (Edexcel A-level Biology B)

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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.
Apoplastic & symplastic pathways (Edexcel A-level Biology B)
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Apoplastic & symplastic pathways (Edexcel A-level Biology B)

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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.
Xylem and phloem (Edexcel A-level Biology B)
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Xylem and phloem (Edexcel A-level Biology B)

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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.
Bohr effect (Edexcel A-level Biology B)
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Bohr effect (Edexcel A-level Biology B)

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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.
The role of haemoglobin and dissociation curves (Edexcel A-level Biology B)
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The role of haemoglobin and dissociation curves (Edexcel A-level Biology B)

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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.
Blood clotting (Edexcel A-level Biology B)
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Blood clotting (Edexcel A-level Biology B)

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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.