This lesson describes the structures and functions of the components of the mammalian gaseous exchange system. The PowerPoint and accompanying resources have been designed to cover point 3.1.1 [c] of the OCR A-level Biology A specification and contains links to future topics such as transport in animals as well as prior knowledge checks of their recall of the content of previously covered modules. The lesson is filled with a range of activities such as guided discussion periods, exam-style questions (with markschemes) and quiz competitions and these run alongside the slides containing the detailed A-level Biology content to cover the following features: The incomplete rings of cartilage, ciliated pseudostratified columnar epithelium and goblet cells in the trachea The narrowing airways of the primary, secondary and tertiary bronchi The elastic fibres and smooth muscle in the terminal and respiratory bronchioles and the change from simple columnar epithelium to simple cuboidal epithelium The large surface area to volume ratio and the simple squamous epithelium of the alveoli The pleural cavity and fluid of the lungs When describing the production of mucus by the goblet cells in the trachea, time is taken to consider cystic fibrosis and the inheritance of this autosomal recessive disorder. Students will be supported in working out genotypes from a pedigree tree to prepare them for module 6.1.2 (Patterns of inheritance)

This lesson describes the gross structure of the human gas exchange system and the functions of the structural components like goblet cells. The PowerPoint and accompanying resources have been designed to cover points 9.1 (a & c) of the CIE A-level Biology specification and has been specifically planned to prepare students for an upcoming lesson where the gas exchange between the alveoli and the blood is described. The lesson is filled with a range of activities such as guided discussion periods, exam-style questions (with markschemes) and quiz competitions and these run alongside the slides containing the detailed A-level Biology content to cover the following features: The incomplete rings of cartilage, ciliated pseudostratified columnar epithelium and goblet cells in the trachea The narrowing airways of the primary, secondary and tertiary bronchi The elastic fibres and smooth muscle in the terminal and respiratory bronchioles The pleural cavity and fluid of the lungs When describing the production of mucus by the goblet cells in the trachea, time is taken to consider cystic fibrosis and the inheritance of this autosomal recessive disorder. Students will be supported in working out genotypes from a pedigree tree to prepare them for topic 16 (Inherited change)

This lesson describes the gross structure of the human gas exchange system, including the trachea, bronchi, bronchioles and lungs. The PowerPoint and accompanying resources are part of the third lesson in a series of 6 which have been designed to cover the detail of topic 3.2 in the AQA A-level Biology specification which is titled gas exchange and this lesson has been specifically planned to prepare students for the next lesson where the essential features of the alveoli are described. The lesson is filled with a range of activities such as guided discussion periods, exam-style questions (with markschemes) and quiz competitions and these run alongside the slides containing the detailed A-level Biology content to cover the following features: The incomplete rings of cartilage, ciliated pseudostratified columnar epithelium and goblet cells in the trachea The narrowing airways of the primary, secondary and tertiary bronchi The elastic fibres and smooth muscle in the terminal and respiratory bronchioles The pleural cavity and fluid of the lungs When describing the production of mucus by the goblet cells in the trachea, time is taken to consider cystic fibrosis and the inheritance of this autosomal recessive disorder. Students will be supported in working out genotypes from a pedigree tree to prepare them for the topic of inheritance (7.1)

This lesson explains why large organisms with a low surface area to volume ratio need specialised gas exchange surfaces and a mass transport system. The PowerPoint and accompanying worksheets have been designed to cover points 4.1 (i & ii) of the Edexcel A-level Biology B specification and have been specifically planned to prepare students for the upcoming lessons on gas exchange (4.3) and circulation (4.4) The students are likely to have been introduced to the surface area to volume ratio at GCSE, but understanding of its relevance tends to be mixed. Therefore, real life examples are included throughout the lesson that emphasise the importance of this ratio in order to increase this relevance. A lot of students worry about the maths calculations that are associated with this topic so a step by step guide is included at the start of the lesson that walks them through the calculation of the surface area, the volume and then the ratio. Through worked examples and understanding checks, SA/V ratios are calculated for cubes of increasing side length and living organisms of different size. These comparative values will enable the students to conclude that the larger the organism or structure, the lower the surface area to volume ratio. A differentiated task is then used to challenge the students to explain the relationship between the ratio and the metabolic demands of a single-celled and multicellular organisms and this leads into the next part of the lesson, where the adaptations of large organisms to increase this ratio at the exchange surfaces are covered. The students will calculate the SA/V ratio of a human alveolus (using the surface area and volume formulae for a sphere) and will see the significant increase that results from the folding of the membranes. In addition to the ratio, time is taken to discuss and describe how the maintenance of a steep concentration gradient and a thin membrane are important for the rate of diffusion and again biological examples are used in humans and other organisms to increase the understanding. Fick’s law of diffusion is also introduced as a mechanism to help the students to recall that surface area, concentration difference and thickness of membrane govern the rate of simple diffusion. The final part of the lesson considers how a mass transport system is needed alongside the specialised gas exchange surface to allow the oxygen to be delivered to the respiring cells to enable them to continue to carry out aerobic respiration to generate ATP.

This lesson explains the need for specialised exchange surfaces and uses examples to describe the features of an efficient exchange surface. The PowerPoint and accompanying worksheets have been designed to cover points 3.1.1 (a & b) of the OCR A-level Biology A specification and also have been specifically planned to prepare the students for the upcoming lessons in module 3 on gas exchange and mass transport in animals. The students are likely to have been introduced to the surface area to volume ratio at GCSE, but understanding of its relevance tends to be mixed. Therefore, real life examples are included throughout the lesson that emphasise the importance of this ratio in order to increase this relevance. A lot of students worry about the maths calculations that are associated with this topic so a step by step guide is included at the start of the lesson that walks them through the calculation of the surface area, the volume and then the ratio. Through worked examples and understanding checks, SA/V ratios are calculated for cubes of increasing side length and living organisms of different size. These comparative values will enable the students to conclude that the larger the organism or structure, the lower the surface area to volume ratio. A differentiated task is then used to challenge the students to explain the relationship between the ratio and the metabolic demands of a single-celled and multicellular organisms and this leads into the next part of the lesson, where the adaptations of large organisms to increase this ratio at the exchange surfaces are covered. The students will calculate the SA/V ratio of a human alveolus (using the surface area and volume formulae for a sphere) and will see the significant increase that results from the folding of the membranes. In addition to the ratio, time is taken to discuss and describe how the maintenance of a steep concentration gradient and a thin membrane are important for the rate of diffusion and again biological examples are used in humans and other organisms to increase the understanding. Fick’s law of diffusion is also introduced as a mechanism to help the students to recall that surface area, concentration difference and thickness of membrane govern the rate of simple diffusion. As well as making links to upcoming topics, prior knowledge checks are used to challenge the students on their knowledge of previously-covered modules which include inorganic ions, organelles, cell membrane transport and tissues.

This lesson describes how Fick’s law of diffusion is governed by the three main properties of gas exchange surfaces in living organisms. The PowerPoint and accompanying worksheets have been designed to cover points 2.1 (i & ii) of the Edexcel International A-level Biology specification and there is a particular focus on the relationship between the size of an organism or structure and its surface to volume ratio. Adolf Fick is briefly introduced at the start of the lesson and the students will learn that his law of diffusion governs the diffusion of a gas across a membrane and is dependent on three properties. The students are likely to know that surface area is one of these properties but although they may have been introduced to the surface area to volume ratio at iGCSE, their understanding of its relevance tends to be mixed. Therefore, real life examples are included throughout the lesson that emphasise the importance of this ratio in order to increase the relevance. A lot of students worry about the maths calculations that are associated with this topic so a step by step guide is included at the start of the lesson to walk them through the calculation of the surface area, the volume and then the ratio. Through worked examples and understanding checks, SA/V ratios are calculated for cubes of increasing side length and living organisms of different size. These comparative values will enable the students to conclude that the larger the organism or structure, the lower the surface area to volume ratio. A differentiated task is then used to challenge the students to explain the relationship between the ratio and the metabolic demands of an organism and this leads into the next part of the lesson, where the adaptations of a human to increase the ratio at the gas exchange surface is covered. The students will calculate the SA/V ratio of a human alveolus (using the surface area and volume formulae for a sphere) and will see the significant increase that results from the folding of the membranes. The remainder of the lesson introduces concentration difference and thickness of membrane as the other two properties in Fick’s law of diffusion and students are reminded that the maintenance of a steep concentration gradient and a reduction in the diffusion distance are critical for this transport mechanism. This lesson has been specifically planned to prepare students for the next lesson which describes how the structure of the mammalian lung is adapted for rapid gas exchange (specification point 2.1 [iii])

This lesson describes the properties of gas exchange surfaces and shows how Fick’s law of diffusion is dependent on these properties. The PowerPoint and accompanying worksheets have been designed to cover points 2.1 (i & ii) of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification and there is a particular focus on the relationship between the size of an organism or structure and its surface to volume ratio. Adolf Fick is briefly introduced at the start of the lesson and the students will learn that his law of diffusion governs the diffusion of a gas across a membrane and is dependent on three properties. The students are likely to know that surface area is one of these properties but although they may have been introduced to the surface area to volume ratio at GCSE, their understanding of its relevance tends to be mixed. Therefore, real life examples are included throughout the lesson that emphasise the importance of this ratio in order to increase the relevance. A lot of students worry about the maths calculations that are associated with this topic so a step by step guide is included at the start of the lesson to walk them through the calculation of the surface area, the volume and then the ratio. Through worked examples and understanding checks, SA/V ratios are calculated for cubes of increasing side length and living organisms of different size. These comparative values will enable the students to conclude that the larger the organism or structure, the lower the surface area to volume ratio. A differentiated task is then used to challenge the students to explain the relationship between the ratio and the metabolic demands of an organism and this leads into the next part of the lesson, where the adaptations of a human to increase the ratio at the gas exchange surface is covered. The students will calculate the SA/V ratio of a human alveolus (using the surface area and volume formulae for a sphere) and will see the significant increase that results from the folding of the membranes. The remainder of the lesson introduces concentration difference and thickness of membrane as the other two properties in Fick’s law of diffusion and students are reminded that the maintenance of a steep concentration gradient and a reduction in the diffusion distance are critical for this transport mechanism. This lesson has been specifically planned to prepare students for the next lesson which describes how the structure of the mammalian lung is adapted for rapid gas exchange (specification point 2.1 [iii])

This lesson describes the relationship between the size of an organism or structure and its surface to volume ratio. The PowerPoint and accompanying worksheets have been designed to cover point 3.1 of the AQA A-level Biology specification and also have been specifically planned to prepare the students for the upcoming lessons in topic 3 on gas exchange and absorption in the ileum. The students are likely to have been introduced to the ratio at GCSE, but understanding of its relevance tends to be mixed. Therefore, real life examples are included throughout the lesson that emphasise the importance of the surface area to volume ratio in order to increase this relevance. A lot of students worry about the maths calculations that are associated with this topic so a step by step guide is included at the start of the lesson that walks them through the calculation of the surface area, the volume and then the ratio. Through worked examples and understanding checks, SA/V ratios are calculated for cubes of increasing side length and living organisms of different size. These comparative values will enable the students to conclude that the larger the organism or structure, the lower the surface area to volume ratio. A differentiated task is then used to challenge the students to explain the relationship between the ratio and the metabolic demands of an organism and this leads into the next part of the lesson, where the adaptations of larger organisms to increase the ratio at their exchange surfaces is covered. The students will calculate the SA/V ratio of a human alveolus (using the surface area and volume formulae for a sphere) and will see the significant increase that results from the folding of the membranes. This is further demonstrated by the villi and the microvilli on the enterocytes that form the epithelial lining of these folds in the ileum. The final part of the lesson introduces Fick’s law of diffusion so that students are reminded that the steepness of a concentration gradient and the thickness of a membrane also affect the rate of diffusion.

This lesson describes the relationship between the specialised features of the mammalian egg and sperm and their functions. The PowerPoint and accompanying resources have been designed to cover point 3.11 of the Edexcel International A-level Biology specification and includes a focus on the acrosome in the head of the sperm and the zona pellucida in the egg The lessons at the start of topic 3 (Cell structure, Reproduction and Development) described the ultrastructure of eukaryotic cells, so this knowledge is referenced throughout the lesson and the students are challenged on their recall and understanding through a range of prior knowledge checks. For example, two of the exam-style questions that are included in the resources challenge the students to explain why a sperm cell is classified as an eukaryotic cell and to recognise the centrioles and the nucleus from structural descriptions. Along with the mitochondria, time is then taken to discuss and to describe the role of these organelles in relation to the function of the sperm cell. When considering the fusion of the haploid nuclei to form a diploid nucleus in the nucleus, links are made to the upcoming topic of mitosis and the significance of this form of nuclear division. The importance of the enzymes that are found inside the acrosome is emphasised and this leads into the second half of the lesson where the layers surrounding the plasma membrane of the egg cell (corona radiata and zona pellucida) are examined The final part of this lesson has been specifically planned to prepare the students for the next lesson in topic 3, where the acrosome reaction, cortical reaction and the fusion of nuclei that are involved in fertilisation are described

This lesson describes the relationship between the specialised structural features of the mammalian gametes and their functions. The PowerPoint and accompanying resources have been designed to cover point 3.6 of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification and includes descriptions of the acrosome in the head of the sperm and the zona pellucida in the egg The lessons at the start of topic 3 (Voice of the genome) described the ultrastructure of eukaryotic cells, so this knowledge is referenced throughout the lesson and the students are challenged on their recall and understanding through a range of prior knowledge checks. For example, two of the exam-style questions that are included in the resources challenge the students to explain why a sperm cell is classified as an eukaryotic cell and to recognise the centrioles and the nucleus from structural descriptions. Along with the mitochondria, time is then taken to discuss and to describe the role of these organelles in relation to the function of the sperm cell. When considering the role of the haploid nucleus, links are made to the upcoming topic of meiosis and the events that contribute to variation. The importance of the enzymes that are found inside the acrosome is emphasised and this leads into the second half of the lesson where the layers surrouding the plasma membrane of the egg cell (corona radiata and zona pellucida) are examined The final part of this lesson has been specifically planned to prepare the students for the next lesson in topic 3, where the acrosome reaction, cortical reaction and the fusion of nuclei that are involved in fertilisation are described

This lesson describes the transport mechanism of osmosis as the movement of water molecules from a high water potential to a lower water potential. The PowerPoint and accompanying resources are part of the second lesson in a series of 4 lessons which have been designed to cover point [c] as detailed in AS unit 1, topic 3 of the WJEC A-level Biology specification and also describes how cells are affected by this movement of water 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 when animal and plant cells are suspended in hypotonic, hypertonic or isotonic solutions and the final appearance of these cells is described, including any issues this may cause.

This lesson describes how molecules move across the cell membrane by the transport mechanisms of (simple) diffusion and facilitated diffusion. The PowerPoint and accompanying resources are the first lesson in a series of 4 lessons which have been designed to cover the detail of point [c] in unit 1, topic 3 of the WJEC A-level Biology specification and the factors that increase the rate of diffusion are covered along with the limitations imposed by the phospholipid bilayer and the role of channel and carrier proteins. The structure and properties of cell membranes were described in the lesson covering point (a) of this topic, 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

This lesson describes the principle components of the plasma membrane, focusing on the phospholipid bilayer and membrane proteins. The detailed PowerPoint and accompanying worksheets have been designed to cover the detail in point (a) of AS unit 1, topic 3 of the WJEC A-level Biology specification and clear links are made to Singer and Nicholson’s fluid mosaic model The fluid mosaic model is introduced at the start so that it can be referenced at appropriate points throughout the lesson. Students were introduced to phospholipids in topic 1 and so an initial task challenges them to spot the errors in a passage describing the structure and properties of this molecule. This reminds them of the bilayer arrangement, with the hydrophilic phosphate heads protruding outwards into the aqueous solutions on the inside and the outside of the cell. In a link to some upcoming lessons on the transport mechanisms, the students will learn that only small, non-polar molecules can move by simple diffusion and that this is through the tails of the bilayer. This introduces the need for transmembrane proteins to allow large or polar molecules to move into the cell by facilitated diffusion and active transport. Proteins that act as receptors as also introduced and an opportunity is taken to make a link to an upcoming topic so that students can understand how hormones or drugs will bind to target cells in this way. Moving forwards, the structure of cholesterol is covered and students will learn that this hydrophobic molecule sits in the middle of the tails and therefore acts to regulate membrane fluidity. The final part of the lesson challenges the students to apply their newly-acquired knowledge to a series of questions where they have to explain why proteins may have moved when two cells are used and to suggest why there is a larger proportion of these proteins in the inner mitochondrial membrane than the outer membrane.

This lesson describes the mechanisms by which the products of digestion are absorbed by the cells lining the ileum. The PowerPoint and accompanying resources are part of the second lesson in a series of 2 which cover the content detailed in point 3.3 of the AQA A-level Biology specification and focuses on the relationship between the structure and function of this section of the small intestine. This lesson has been specifically planned to challenge the students on their understanding of digestion in the mouth, the stomach and the duodenum as covered in the previous lesson and to build on this knowledge to allow them to recognise how the products of digestion are then absorbed in the ileum. Time is taken to describe how the folds of the ileum known as villi and the multiple microvilli found on each villus act to significantly increase the surface area for absorption and the adsorption of enzymes. The mechanism of co-transport was described in topic 2.3 so a series of exam-style questions are then used to check that the students can explain how these proteins are used to absorb monosaccharides and amino acids from the ileum. The remainder of the lesson explains why the formation of micelles is critical for the absorption of monoglycerides and fatty acids

This lesson describes how large molecules are hydrolysed to smaller molecules by the enzymes produced by the digestive system in mammals. The detailed PowerPoint and accompanying worksheets are part of the 1st lesson in a series of 2 which have been designed to cover the content of point 3.3 of the AQA A-level Biology specification and this lesson includes descriptions of the action of amylase, disaccharidases, lipase, endopeptidases, exopeptidases and dipeptidases. The lesson has been designed to walk the students through the functions of the digestive system at each point of the digestive tract up until the duodenum and focuses on the action of the enzymes produced in the mouth, stomach and small intestine and by the accessory organs of the system. Time is taken to describe and explain key details, such as the fact that endopeptidases cleave peptide bonds within the molecules, meaning that they cannot break down proteins into monomers. The lesson is filled with exam-style questions which will develop their understanding of the current topic as well as checking on their knowledge of related topics which have been previously-covered such as the structure of the biological molecules and qualitative tests. In addition to the detailed content and regular questioning, the lesson PowerPoint contains guided discussion periods and two quick quiz competitions which introduce a key term and a key value in a fun and memorable way This lesson has been specifically planned to prepare the students for the very next lesson where the mechanisms for the absorption of the products of digestion are described.