This lesson describes how the eyepiece graticule and stage micrometer are used in the measurement of cells. The engaging PowerPoint and accompanying resources have been designed to cover point 1.1 [c] of the CIE A-level Biology specification and also includes a number of tasks that have been written to ensure that students are able to recognise the millimetre, micrometre and nanometre as units of size and that they are able to convert between them. As this content is part of topic 1.1, it is likely that this lesson on the measurement of cells and the units of size will be one of the first that students will encounter in this A-level course. With this in mind, this lesson and the next two on microscopes and calculating actual size have been specifically written to contain a wide variety of tasks, including an ongoing quiz competition. This will act to maintain engagement in a topic that can sometimes discourage students at this early stage of the course whilst ensuring that the key content is covered and understanding is constantly checked. A step by step guide walks them through the use of the scale on the stage micrometer to identify the size of the divisions of the eyepiece graticule and then they are challenged to apply this method to a series of questions. Useful hints are provided throughout the lesson and students will be able to confidently convert between metres, millimetres, micrometres and nanometres by the end of the lesson A quiz scoresheet is included with the lesson so that teachers can keep track of the points won in the different rounds and add them to those won in the upcoming lessons in topic 1.1

This fully-resourced lesson describes the ultrastructure of a prokaryotic cell including the nucleoid, plasmid, 70S ribosomes and cell wall. The engaging PowerPoint and accompanying resources have been designed to cover specification point 2.1 (iii) of the Edexcel A-level Biology B specification but has been specifically designed to be taught after the lesson on the ultrastructure of eukaryotic cells, specification point 2.1 (v), so that comparisons can be drawn. A clear understanding of terminology is important for A-level Biology so this lesson begins with a challenge, where the students have to come up with a 3-letter prefix that they believe will translate as before or in front of . This leads into the discovery of the meaning of prokaryote as before nucleus which acts to remind students that these types of cell lack this cell structure. Links to the previous lessons on the eukaryotic cells are made throughout the lesson and at this particular point, the students are asked to work out why the DNA would be described as naked and to state where it will be found in the cell. Moving forwards, the students will discover that these cells also lack membrane bound organelles and a quick quiz competition challenges them to identify the specific structure that is absent from just a single word. In addition to the naked DNA, students will learn that there are also ribosomes in the cytoplasm and will discover that these are smaller than those found in the cytoplasm of an eukaryotic cell (but the same size as those in chloroplasts and mitochondria). The remainder of the lesson focuses on the composition of the cell wall, the additional features of prokaryotic cells such as plasmids and there is also the introduction of binary fission as the mechanism by which these organisms reproduce so that students can recognise that prokaryotic cells do not contain centrioles

This fully-resourced lesson describes the structure of the cell surface membrane and references Singer and Nicholson’s fluid mosaic model. The detailed and engaging PowerPoint and accompanying resources have been designed to cover specification point 4.2 (i) of the Edexcel A-level Biology B specification and also makes clear links are made to related topics such as the binding of hormones as covered in topic 9 and the electron transport chain as covered in topic 5. The fluid mosaic model is introduced at the start of the lesson so that it can be referenced at appropriate points throughout the lesson. Students were introduced to phospholipids in topic 1 and 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 topic 9 so that students can understand how hormones or drugs will bind to target cells in this way and cause the release of cAMP on the interior of the cell. 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 how the immune system uses molecules on the surface of a cell to identify it, focusing on the identification of pathogens by their antigens. The PowerPoint and accompanying resources which are differentiated are part of the 1st lesson in the series of 7 that cover the content detailed in topic 2.4 of the AQA A-level Biology specification. As this is the first lesson in topic 2.4, it has been specifically planned to introduce a number of key concepts which include phagocytosis, T and B cells, antibodies and memory cells so that students are prepared for upcoming lessons. The lesson begins by challenging the students to use their knowledge of cells to recall the common internal components of a cell before they are informed that all cells also have molecules on their outer membrane. Students will recognise that these molecules are used by the immune system for identification before a quick quiz competition reveals that this allows toxins, abnormal body cells and pathogens to be identified. Moving forwards, the next part of the lesson focuses on the antigens that are found on the outside of a pathogen and links are made to upcoming lesson topics which include: phagocytosis following the identification of a pathogen antigen-presentation by macrophages and dendritic cells production of antibodies which are specific to the antigens the use of antigens in a vaccination program The final task challenges the students to describe and explain how antigen variability will affect disease and disease prevention and this task has been differentiated two ways to allow students of differing abilities to be challenged and supported.

This lesson describes the structure and ultrastructure of plant cells to allow students to compare this structure against animal cell structure. The detailed PowerPoint and accompanying resources have been designed to cover points 4.1 (i) & (ii) in unit 2 of the Edexcel International A-level Biology specification and also describes the functions of the cell wall, chloroplast, amyloplast, vacuole, tonoplast, plasmodesmata, pits and middle lamella The lesson begins with a task called REVERSE GUESS WHO which will challenge the students to recognise a particular organelle from a description of its function. This will remind students that plant cells are eukaryotic and therefore contain a cell-surface membrane, a nucleus (+ nucleolus), a mitochondria, a Golgi apparatus, ribosomes and rough and smooth endoplasmic reticulum like the animal cells. Moving forwards, the next part of the lesson focuses on the relationship between the structure and function of the vacuole, chloroplast, plasmodesmata and cellulose cell wall. When considering the vacuole, key structures such as the tonoplast are described as well as critical functions including the maintenance of turgor pressure. A detailed knowledge of the structure of the chloroplast at this early stage of their A-level studies will increase the likelihood of a clear understanding of photosynthesis when covered in topic 5. For this reason, time is taken to consider the light-dependent and light-independent reactions and to explain how these stages are linked. Students will learn that chloroplasts and amyloplasts can contain stores of starch so an opportunity is taken to challenge them on their knowledge of this polysaccharide as it was covered in topic 1. The final task challenges them to recognise descriptions of the cell wall, chloroplast, amyloplasts, vacuole, tonoplast and plasmodesmata which will leave 2 remaining which describe the pits and middle lamella.

This fully-resourced lesson describes how rod cells in the mammalian retina detect stimuli to allow vision in low light intensity. The detailed PowerPoint and accompanying resources have been designed to cover the second part of point 8.5 of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification and includes reference to the roles of rhodopsin, opsin, retinal, sodium ions, cation channels and hyperpolarisation in the formation of action potentials in the optic neurones. It is likely that students will be aware that the human retina contains rod and cone cells, so this lesson builds on that knowledge and adds the detail needed at this level. Students will discover that the optical pigment in rod cells is rhodopsin and that the bleaching of this into retinal and opsin results in a cascade of events that allows an action potential to be initiated along the optic nerve. Time is taken to go through the events that occur in the dark and then the students are challenged to use this as a guide when explaining how the events differ in the light. Key terms like depolarisation and hyperpolarisation, that were met earlier in topic 8, are used to explain the changes in membrane potential and the resulting effect on the connection with the bipolar and ganglion cells is then described.

This fully-resourced lesson describes how the functional differences of the retinal rod and cone cells is related to their structures. The detailed PowerPoint and accompanying resources are part of the 2nd in a series of 2 lessons that have been designed to cover the details included in point 6.1.2 of the AQA A-level Biology specification. However, as explained at the start of the lesson, it has been specifically planned to be taught after the lessons in topic 6.3, so that students are aware and understand the meaning of terms such as depolarisation and hyperpolarisation. It is likely that students will be aware that the human retina contains rod and cone cells, so this lesson builds on that knowledge and adds the detail needed at this level. Over the course of the lesson, students will learn that these cells contain different optical pigments and that this feature along with their differing connectivity to the bipolar neurones means that they have different sensitivities to light, colour perception and visual acuity. Exam-style questions are interspersed throughout to check on current understanding and also make links to previously covered topics. For example, students are challenged to recognise a description of the mitochondria so they can discover that this cell structure is found in the inner segment where it is responsible for generating the ATP needed to pump sodium ions out of the cells. As detailed above, this lesson ties in closely with topic 6.3 and students will be expected to make links to synapses and to the changes in membrane potential that occur when sodium ions move in or out of a cell

This lesson describes how the nervous system detects stimuli, focusing on the detection of light by the rods in the the retina of mammals. The PowerPoint has been designed to cover the content of specification point 8.8 of the Edexcel International A-level Biology specification and includes descriptions of the roles of rhodopsin, opsin, retinal, sodium ions, cation channels and hyperpolarisation in the formation of action potentials in the optic neurones. The lesson begins by using a quiz to get the students to recognise the range of stimuli which can be detected by receptors. This leads into a task where the students have to form 4 sentences to detail the stimuli which are detected by certain receptors and the energy conversion that happen as a result. Students will be introduced to the idea of a transducer and learn that receptors always convert to electrical energy which is the generator potential. It is likely that students will be aware that the human retina contains rod and cone cells, so the next part of the lesson builds on that knowledge and adds the detail needed at this level. Students will discover that the optical pigment in rod cells is rhodopsin and that the bleaching of this into retinal and opsin results in a cascade of events that allows an action potential to be initiated along the optic nerve. Time is taken to go through the events that occur in the dark and then the students are challenged to use this as a guide when explaining how the events differ in the light. Key terms like depolarisation and hyperpolarisation, that were met earlier in topic 8, are used to explain the changes in membrane potential and the resulting effect on the connection with the bipolar and ganglion cells is then described. The remainder of the lesson focuses on the Pacinian corpuscle and describes how this responds to pressure on the skin, resulting in the opening of the sodium channels and the flow of sodium ions into the neurone to cause depolarisation

This lesson describes how the cells of multicellular organisms are organised into tissues, tissues into organs and organs into systems. The detailed and engaging PowerPoint and accompanying resources have been designed to cover point 3.13 of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification and focuses on the levels of organisation in humans and plants The lesson begins by using the process of haematopoiesis from haematopoietic stem cells to demonstrate how the red blood cell and neutrophil differ significantly in structure despite arising from the same cell along the same cell lineage. A series of exam-style questions will not only challenge their knowledge of structure but also their ability to apply this knowledge to unfamiliar situations. These differences in cell structure is further exemplified by the epithelial cells of the respiratory tract and students are challenged to remember how the shape and arrangement of these cells differ in the trachea and alveoli in relation to their function. The link between specialised cells and tissues is made at this point of the lesson so students are reminded that a tissue is a group of cells that work together to perform a specific function or set of functions. Moving forwards, a quick quiz competition will challenge the students to recognise the liver, kidney, spinal cord and pancreas from a brief functional description and this leads into a series of questions that links back to topics 1 and 2 and earlier in topic 3 where blood clotting, proteins, osmosis, organelles, methods of transport, carbohydrates and enzymes were originally covered. These prior knowledge checks are found throughout the lesson, along with current understanding checks, and all of the mark schemes are embedded into the PowerPoint to allow students to assess their progress. In terms of organ systems, a quick task challenges them to recognise 8 of the 11 that are found in humans from descriptions and this leaves them to identify the gaseous exchange, digestive and reproductive systems as the remaining 3. This leads into a section about cystic fibrosis as this genetic disorder impairs the functioning of these systems. The remainder of the lesson focuses on specialised plant cells and the differing shapes and features of the palisade and spongy cells in the mesophyll layer and the guard cells are covered at length and in detail. The cells found in the xylem and phloem tissue are also discussed.

This fully-resourced lesson describes the meaning of the terms stem cell, pluripotency and totipotency. The PowerPoint and accompanying worksheets have been designed to cover points 3.11 (i) and (ii) of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification and therefore this lesson also contains discussion periods where the topic is the decisions that the scientific community have to make about the use of stem cells in medical therapies. The lesson begins with a knowledge recall of the structure of eukaryotic cells and the students have to use the first letters of each of the four answers to reveal the key term, stem cell. Time is then taken to consider the meaning of cellular differentiation, and this leads into the key idea that not all stem cells are equal when it comes to the number of cell types that they have the potential to differentiate into. A quick quiz round introduces the five degrees of potency, and then the students are challenged to use their understanding of terminology to place totipotency, pluripotency, multipotency, oligopotency and unipotency in the correct places on the potency continuum. Although the latter three do not have to be specifically known based on the content of specification point 3.11 (i), an understanding of their meaning was deemed helpful when planning the lesson as it should assist with the retention of knowledge about totipotency and pluripotency. These two highest degrees of potency are the main focus of the lesson, and key details are emphasised such as the ability of totipotent cells to differentiate into any extra-embroyonic cell, which the pluripotent cells are unable to do. The morula, and inner cell mass and trophoblast of the blastocyst are used to demonstrate these differences in potency. The final part of the lesson discusses the decisions that the scientific community have to make about the use of embryonic stem cells, adult stem cells and also foetal stem cells which allows for a link to chorionic villus sampling from topic 2. There is also a Maths in a Biology context question included in the lesson (when introducing the morula) to ensure that students continue to be prepared for the numerous calculations that they will have to tackle in the terminal exams. This resource has been differentiated two ways to allow students of differing abilities to access the work

This lesson describes the meaning of the term stem cell and the differences between totipotent, pluripotent and multipotent stem cells. The PowerPoint and accompanying worksheets have been designed to cover points 7.3 (i) and (ii) of the Edexcel A-level Biology B specification meaning that this lesson also contains discussion periods about the potential opportunities to use stem cells from embryos in medicine. The lesson begins with a knowledge recall of the structure of eukaryotic cells and the students have to use the first letters of each of the four answers to reveal the key term, stem cell. Time is then taken to consider the meaning of cellular differentiation, and this leads into the key idea that not all stem cells are equal when it comes to the number of cell types that they have the potential to differentiate into. A quick quiz round introduces the five degrees of potency, and then the students are challenged to use their understanding of terminology to place totipotency, pluripotency, multipotency, oligopotency and unipotency in the correct places on the potency continuum. Although the latter two do not have to be specifically known based on the content of specification point 7.3 (i), an understanding of their meaning was deemed helpful when planning the lesson as it should assist with the retention of knowledge about totipotency, pluripotency and multipotency. These three highest degrees of potency are the main focus of the lesson, and key details are emphasised such as the ability of totipotent cells to differentiate into any extra-embroyonic cell, which the pluripotent cells are unable to do. The morula, and inner cell mass and trophoblast of the blastocyst are used to demonstrate these differences in potency. The final part of the lesson discusses the decisions that the scientific community have to make about the use of pluripotent embryonic stem cells, adult stem cells and also multipotent foetal stem cells As there is a heavy mathematical content in the current A-level Biology exams, a Maths in a Biology context question is included in the lesson (when introducing the morula) to ensure that students continue to be prepared for the numerous calculations that they will have to tackle in the terminal exams. This resource has been differentiated two ways to allow students of differing abilities to access the work

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