This fully-resourced lesson describes the ultrastructure of a prokaryotic cell including the cell wall, capsule,plasmid, flagellum, pili, ribosomes, mesosomes and circular DNA. The engaging PowerPoint and accompanying resources have been designed to cover the specification point 3.4 that is detailed in the Pearson Edexcel A-level Biology A specification but also makes continual references to eukaryotic cells as covered in 3.1 - 3.3 so that comparisons can be made. 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 control of gene expression at a post-transcriptional level through the removal of introns during splicing. The detailed PowerPoint and accompanying resources have been designed to cover the second part of point 6.1.1 (b) as detailed in the OCR A-level Biology A specification and also explains how it’s possible for 1 gene to give rise to multiple products as a result of this post-transcriptional modification of mRNA. The lesson begins with a knowledge recall as the students have to recognise the definition of a gene as a sequence of bases on a DNA molecule that codes for a sequence of amino acids in a polypeptide chain. This description was introduced in module 2.1.3 and the aim of the start of the lesson is to introduce the fact that despite this definition, most of the nuclear DNA in eukaryotes doesn’t actually code for proteins. A quick quiz competition is then used to introduce exons as the coding regions within a gene before students are challenged to predict the name of the non-coding regions and then to suggest a function for these introns. At this point, the students will complete a task that acts as a prior knowledge check where they have to identify the 6 errors in the descriptive passage about the lac operon and its role in the regulation of gene expression in prokaryotes. Moving forwards, pre-mRNA as a primary transcript is introduced and students will learn that this isn’t the mature strand that moves off to the ribosome for translation. Instead, a process called splicing takes place where the introns are removed and the remaining exons are joined together. Another quick quiz round leads to an answer of 20000 and students will learn that this is the number of protein-coding genes in the human genome. Importantly, the students are then told that the number of proteins that are synthesised is much higher than this value and a period of class discussion encourages them to come up with biological suggestions for this discrepancy between the two numbers. The lesson concludes with a series of understanding and application questions where students will learn that alternative splicing enables a gene to produce more than a single protein and that this natural phenomenon greatly increases biodiversity

This fully-resourced lesson describes the regulatory mechanisms that control gene expression at a transcriptional level. The detailed PowerPoint and accompanying resources have been designed to cover the first part of point 6.1.1 (b) as detailed in the OCR A-level Biology A specification which states that the students knowledge should include the lac operon and examples of transcription factors in eukaryotes. . This is one of the more difficult concepts in this A-level course and therefore key points are reiterated throughout this lesson to increase the likelihood of student understanding and to support them when trying to make links to actual biological examples in living organisms. There is a clear connection to transcription and translation as covered in module 2.1.3, so the lesson begins by reminding students that in addition to the structural gene in a transcription unit, there is the promotor region where RNA polymerase binds. Students are introduced to the idea of transcription factors and will understand how these molecules can activate or repress transcription by enabling or preventing the binding of the enzyme. At this point, students are challenged on their current understanding with a series of questions about DELLA proteins so they can see how these molecules prevent the binding of RNA polymerase. Their understanding is then tested again with another example with oestrogen and the ER receptor. The final and main section of the lesson focuses on the lac operon and immediately an opportunity is taken to challenge their knowledge of biological molecules with a task where they have to spot the errors in a passage describing the formation and breakdown of this disaccharide. Students will be able to visualise the different structures that are found in this operon and time is taken to go through the individual functions. A step by step guide is used to walk students through the sequence of events that occur when lactose is absent and when it is present before they are challenged to apply their understanding to an exam question.

This fully-resourced lesson describes the beneficial, neutral and harmful effects of gene mutations on the primary structure of a polypeptide. The engaging and detailed PowerPoint and accompanying resources have been designed to cover point 6.1.1 (a) of the OCR A-level Biology A specification which states that students should be able to understand how substitutions, deletions and insertions change the base sequence and describe how this affects protein production and function. In order to understand how a change in the base sequence can affect the order of the amino acids, students must be confident in their understanding and application of protein synthesis which was covered in module 2.1.3. Therefore, the start of the lesson focuses on transcription and translation and students are guided through the use of the codon table to identify amino acids. Moving forwards, a task called known as THE WALL is used to introduce to the names of three types of gene mutation whilst challenging the students to recognise terms which are associated with the genetic code and were met back in 2.1.3. The main focus of the lesson is base substitutions and how these mutations may or may not cause a change to the amino acid sequence. The students are challenged to use their knowledge of the degenerate nature of the genetic code to explain how a silent mutation can result. The rest of the lesson looks at base deletions and base insertions and students are introduced to the idea of a frameshift mutation. One particular task challenges the students to evaluate the statement that base deletions have a bigger impact on primary structure than base substitutions. This is a differentiated task and they have to compare the fact that the reading frame is shifted by a deletion against the change in a single base by a substitution

This fully-resourced lesson describes the movement of molecules by active transport, endocytosis and exocytosis, which are all active process that require ATP. The PowerPoint and accompanying worksheets have been designed to cover the second part of point 2.1.5 (d) [i] of the OCR A-level Biology A specification. The first part of this specification point, concerning simple and facilitated diffusion, was covered in the previous lesson. The start of the lesson challenges the students to use their prior knowledge of biological molecules to come up with the abbreviation ATP. Students were introduced to this molecule in module 2.1.3, so a series of prior knowledge questions are used to check on their recall of the structure and properties of ATP. Students are also reminded that the hydrolysis of ATP can be coupled to energy-requiring reactions within the cell and the rest of the lesson focuses on the use of this energy input for active transport, endocytosis and exocytosis. Students are challenged to answer a series of questions which 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.

This detailed lesson describes the fluid mosaic model of membrane structure and also describes the roles of its components. The detailed and engaging PowerPoint and accompanying worksheets have been designed to cover specification point 2.1.5 (b) of the OCR A-level Biology A specification and clear links are made to related topics such as the binding of peptide hormones 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 module 2.1.2 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 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 how molecules move across the cell membrane by the passive methods of simple and facilitated diffusion. The PowerPoint and accompanying resources have been designed to cover the first part of specification point 2.1.5 (d) [i] of the OCR A-level Biology A 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 2.1.5 (b), 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 detailed lesson describes how the movement of water molecules by osmosis can affect both plant and animal cells. Both the PowerPoint and accompanying resources have been designed to cover specification point 2.1.5 (e) [i] as detailed in the OCR A-level Biology A specification and there is a particular focus on solutions of different water potentials. 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 has been specifically written to tie in with the previous two lessons covering 2.1.5 (b) & (d) where the cell membrane, diffusion and active transport were described.

This fully-resourced lesson describes how selection pressures act on a gene pool and cause stabilising, directional and disruptive selection. The PowerPoint and accompanying resources have been designed to cover point 8.3 (i) of the Edexcel A-level Biology B specification which states that students should be able to identify each type of selection by its effect on different phenotypes. The lesson begins with an introduction to the mark, release, recapture method to calculate numbers of rabbits with different coloured fur in a particular habitat. This shows changes in numbers of the organisms and sketch graphs are then constructed to show these changes in the population size. A quick quiz competition is used to engage the students whilst introducing the names of the three main types of selection before a class discussion point encourages the students to recognise which specific type of selection is represented by the rabbits. Key terminology including intermediate and extreme phenotypes and selection pressure are used to emphasise their importance during explanations. A change in the environment of the habitat and a change in the numbers of the rabbits introduces directional selection before students will be given time to discuss and to predict the shape of the sketch graph for disruptive selection. Students are challenged to apply their knowledge in the final task of the lesson by choosing the correct type of selection when presented with details of a population and answer related questions.

This fully-resourced lesson guides students through the use of the Hardy-Weinberg equation to monitor changes in allele frequencies in a population. The detailed PowerPoint and differentiated practice questions worksheets have been designed to cover point 8.3 (iv) of the Edexcel A-level Biology B specification The lesson begins with a focus on the equation to ensure that the students understand the meaning of each of the terms. The recessive condition, cystic fibrosis, is used as an example so that students can start to apply their knowledge and assess whether they understand which genotypes go with which term. Moving forwards, a step-by-step guide is used to show students how to answer a question. Tips are given during the guide so that common misconceptions and mistakes are addressed immediately. The rest of the lesson gives students the opportunity to apply their knowledge to a set of 3 questions, which have been differentiated so that all abilities are able to access the work and be challenged

This engaging and fully-resourced lesson explores how genetic drift can arise after a population bottleneck or as a result of the Founder effect. The detailed PowerPoint and accompanying resources have been designed to cover points 8.3 (ii) & (iii) of the Edexcel A-level Biology B specification A wide range of examples are used to show the students how a population that descends from a small number of parents will have a reduction in genetic variation and a change in the frequency of existing alleles. Students are encouraged to discuss new information to consider key points and understanding checks in a range of forms are used to enable them to check their progress and address any misconceptions. Students are provided with three articles on Huntington’s disease in South Africa, the Caribbean lizards and the plains bison to understand how either a sharp reduction in numbers of a new population beginning from a handful of individuals results in a small gene pool. Links to related topics are made throughout the lesson to ensure that a deep understanding is gained.

This fully-resourced lesson guides students through the construction of genetic crosses and pedigree diagrams for the inheritance of a single gene. The clear PowerPoint and accompanying resources have been designed to cover point 8.2 (ii) of the Edexcel A-level Biology B specification and includes the inheritance of multiple allele characteristics as well as those that demonstrate codominance. In order to minimise the likelihood of errors and misconceptions, step by step guides have been included throughout the lesson to support the students with the following: Writing parent genotypes Working out the different gametes that are made following meiosis Interpreting Punnett crosses to work out phenotypic ratios Students can often find pedigree trees the most difficult to interpret and to explain so exemplar answers are used as well as differentiated worksheets provided to support those students who need extra assistance.

This fully-resourced lesson describes the inheritance of genes that are carried on the X chromosome and includes a particular focus on haemophilia in humans. The detailed PowerPoint and associated differentiated resources have been designed to cover specification point 8.2 (v) as detailed in the Edexcel A-level Biology B specification. Key genetic terminology is used throughout and the lesson begins with a check on their ability to identify the definition of homologous chromosomes. Students will recall that the sex chromosomes are not fully homologous and that the smaller Y chromosome lacks some of the genes that are found on the X. This leads into one of the numerous discussion points, where students are encouraged to consider whether females or males are more likely to suffer from sex-linked diseases and they will be challenged to find evidence to support this decision later in the lesson. In terms of humans, the lesson focuses on haemophilia and red-green colour blindness and a step-by-step guide is used to demonstrate how these specific genetic diagrams should be constructed and how the phenotypes should then be interpreted. The final tasks of the lesson challenge the students to carry out a dihybrid cross that involves a sex-linked disease and an autosomal disease before applying their knowledge to a question about chickens and how the rate of feather production in chicks can be used to determine gender. All of the tasks are differentiated so that students of differing abilities can access the work and all exam questions have fully-explained, visual markschemes to allow them to assess their progress and address any misconceptions

This fully-resourced lesson has been written to support students to develop a clear understanding of 16 key genetic terms, including the 8 that are detailed in specification point 8.2 (i) of the Edexcel A-level Biology B specification. The 16 terms are genome, gene, chromosome, gene locus, homologous chromosomes, alleles, dominant, recessive, genotype, codominance, multiple alleles, autosomes, sex chromosomes, phenotype, homozygous and heterozygous. As some of these terms were met at GCSE, this fully-resourced lesson has been designed to include a wide range of activities that build on this prior knowledge and provide clear explanations as to their meanings as well as numerous examples of their use in both questions and exemplary answers. The main task provides the students with an opportunity to apply their understanding by recognising a dominance hierarchy in a multiple alleles characteristic and then calculating a phenotypic ratio when given a completed genetic diagram. Other tasks include prior knowledge checks, discussion points to encourage students to consider the implementation of the genetic terms and quiz competitions to introduce new terms, maintain engagement and to act as an understanding check.

This lesson guides students through the use of the chi-squared test to determine the significance of the difference between observed and expected results. It is fully-resourced with a detailed PowerPoint and differentiated worksheets that have been designed to cover point 8.2 (vi) of the Edexcel A-level Biology B specification The lesson includes a step-by-step guide to demonstrates how to carry out the test in small sections. At each step, time is taken to explain any parts which could cause confusion and helpful hints are provided to increase the likelihood of success in exam questions on this topic. Students will understand how to use the phenotypic ratio to calculate the expected numbers and then how to find the critical value in order to compare it against the chi-squared value. A worked example is used to show the working which will be required to access the marks and then the main task challenges the students to apply their knowledge to a series of questions of increasing difficulty. This is the final lesson of topic 8.2 (transfer of genetic information) and links are made throughout the lesson to earlier parts of this topic such as dihybrid inheritance as well as to earlier topics like meiosis

This fully-resourced lesson describes how mutations, the events of meiosis and random fertilisation result in genetic variation. The engaging PowerPoint and accompanying resources have been primarily designed to cover points 8.1 (i) & (ii) of the Edexcel A-level Biology B specification but also includes activities to challenge the students on previous concepts in topics 1 and 2. The students begin the lesson by having to identify phenotype and species from their respective definitions so that a discussion can be encouraged where they will recognise that phenotypic variation within a species is due to both genetic and environmental factors although this lesson only focuses on the genetic aspect. A range of activities, which include exam-style questions and quick quiz rounds, are used to challenge the students on their knowledge and understanding of substitution mutations, deletions, insertions, the genetic code, crossing over and independent assortment. Moving forwards, the concept of multiple alleles is introduced and students will learn how the presence of more than 2 alleles at a locus increases the number of phenotypic variants. The final section of the lesson focuses on the production of haploid gametes by meiosis and discusses how the random fertilisation of these gametes during sexual reproduction further increases variation.

This fully-resourced lesson describes how it’s possible for 1 gene to give rise to multiple products as a result of post-transcriptional modification of mRNA. The detailed PowerPoint and accompanying resources have been designed to cover point 7.2 (iii) of the Edexcel A-level Biology B specification. The lesson begins with a knowledge recall as the students have to recognise the definition of a gene as a sequence of bases on a DNA molecule that codes for a sequence of amino acids in a polypeptide chain. This description was introduced in topic 1 and the aim of the start of the lesson is to introduce the fact that despite this definition, most of the nuclear DNA in eukaryotes doesn’t actually code for proteins. A quick quiz competition is then used to introduce exons as the coding regions within a gene before students are challenged to predict the name of the non-coding regions and then to suggest a function for these introns. At this point, the students will complete a task that acts as a prior knowledge check where they have to identify the 6 errors in the descriptive passage about the lac operon and its role in the regulation of gene expression in prokaryotes. Moving forwards, pre-mRNA as a primary transcript is introduced and students will learn that this isn’t the mature strand that moves off to the ribosome for translation. Instead, a process called splicing takes place where the introns are removed and the remaining exons are joined together. Another quick quiz round leads to an answer of 20000 and students will learn that this is the number of protein-coding genes in the human genome. Importantly, the students are then told that the number of proteins that are synthesised is much higher than this value and a class discussion period encourages them to come up with biological suggestions for this discrepancy between the two numbers. The lesson concludes with a series of understanding and application questions where students will learn that alternative splicing enables a gene to produce more than a single protein and that this natural phenomenon greatly increases biodiversity.

This fully-resourced lesson describes the role of transcription factors in the regulation of gene expression. The detailed PowerPoint and accompanying resources have been designed to cover the details of specification points 7.2 (i) and (ii) of the Edexcel A-level Biology B course. This is one of the more difficult concepts in this A-level course and therefore key points are reiterated throughout this lesson to increase the likelihood of student understanding and to support them when trying to make links to actual biological examples in living organisms. There is a clear connection to transcription and translation as covered in topic 1.4, so the lesson begins by reminding students that in addition to the structural gene in a transcription unit, there is the promotor region where RNA polymerase binds. Students are introduced to the idea of transcription factors and will understand how these molecules can activate or repress transcription by enabling or preventing the binding of the enzyme. At this point, students are challenged on their current understanding with a series of questions about DELLA proteins so they can see how these molecules prevent the binding of RNA polymerase. Their understanding is then tested again with another example with oestrogen and the ER receptor. The final and main section of the lesson focuses on the lac operon. Students will be able to visualise the different structures that are found in this unit of DNA and time is taken to go through the individual functions. A step by step guide is used to walk students through the sequence of events that occur when lactose is absent and when it is present before they are challenged to apply their understanding to an exam question.

This fully-resourced lesson describes the structure, different roles and modes of action of the B and T lymphocytes in the specific immune response. The detailed PowerPoint and accompanying resources have been designed to cover point 4.1.1 (f) as detailed in the OCR A-level Biology A specification and the structure of antibodies and the roles of memory cells is also briefly introduced so that students are prepared for an upcoming lesson on the secondary immune response (4.1.1 g) Antigen presentation was introduced at the end of the previous lesson so the task at the start of this lesson challenges students to recognise the name of this process and then they have to spot the errors in the passage that describes the details of this event. This reminds them that contact between the APC and T lymphocytes is necessary to elicit a response which they will come to recognise as the cellular response. A series of quick quiz rounds reveals key terms in a memorable way and one that is introduced is helper T cells. Time is then taken to describe the importance of cell signalling for an effective response and students will learn how the release of chemicals by these cells activates other aspects of the response. The role of the killer T cells and their production of cytotoxins is also described before an exam-style question is used to check on their understanding at this point of the lesson. This leads into the section of the lesson that deals with the humoral response and students will understand how this involves the antibodies that are produced by the plasma cells that are the result of clonal selection and expansion. The T and B memory cells are also introduced so that students can understand how they are retained in the body even after the pathogen has been overcome and will play a critical role in the development of immunity. The remainder of the lesson focuses on the role of the antibodies and the attachment of phagocytes to opsonins