This detailed lesson explains how the process of transcription results in the production of mRNA. Both the detailed PowerPoint and accompanying question worksheet have been designed to cover the first part of points 2.5 (i) & (ii) of the Pearson Edexcel A-level Biology A specification The lesson begins by challenging the students to work out that most of the nuclear DNA in eukaryotes does not actually code for polypeptides. This allows the promoter region and terminator region to be introduced, along with the structural gene. Through the use of an engaging quiz competition, students will learn that the strand of DNA involved in transcription is known as the template (or anti-sense) strand and the other strand is the coding (or sense) strand. Links to previous lesson on the structure of DNA and RNA are made throughout and students are continuously challenged on their prior knowledge as well as their current understanding of the lesson topic. Moving forwards, the actual process of transcription is covered in a 7 step bullet point description where the students are asked to complete each passage using the information previously provided. An exam-style question is used to check on their understanding before the final task of the lesson looks at the journey of mRNA to the ribosome for the next stage of protein synthesis, translation.

This fully-resourced lesson guides students through the interpretation of genetic pedigree diagrams for the inheritance of a single gene. The clear PowerPoint and accompanying resources have been designed to cover point 2.13 (ii) of the Pearson Edexcel A-level Biology A 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 detailed lesson uses haemoglobin and collagen as examples to describe the structure, properties and functions of globular and fibrous proteins. The engaging PowerPoint and accompanying worksheet have been designed to cover point 2.9 (iv) of the Pearson Edexcel A-level Biology A specification and focuses on the shape, solubility and function of these two types of protein. The first part of the lesson looks at the structure of haemoglobin, and describes how the presence of an iron-containing haem group on the outside of the 4 polypeptide chains explains its ability to form oxyhaemoglobin. Moving forwards, the importance of the solubility of this protein is considered and related to the direction that the hydrophobic R groups point. At this point of the lesson, the students are challenged to construct a comparison table which can be filled in as the lesson progresses and as they are given more details of collagen. The section of the lesson concerning collagen begins with the introduction of its function in the artery wall so that students can recognise how fibrous proteins have roles associated with mechanical strength. Time is taken to discuss their solubility as well as the presence of repetitive amino acid sequences. The remainder of the lesson considers four more proteins and the final task challenges the students to use their completed table to write a summary passage comparing globular and fibrous proteins.

This lesson describes how the expression of a gene mutation impairs the functioning of the organ systems in people with cystic fibrosis. The detailed PowerPoint and accompanying worksheets have primarily been designed to cover point 2.16 in AS unit 1 of the Edexcel International A-level Biology specification but also challenge the students on their knowledge of previously-covered topics such as inheritance, protein synthesis and the genetic code as well as making links to the upcoming topics of loci and post-transcriptional changes. The main focus of the lesson is the CFTR gene and the functions of the ion channel that is synthesised when this gene is expressed. As well as explaining that this channel allows chloride ions to flow across the apical membrane of the epithelial cells, time is taken to emphasise the importance of its inhibition on the ENaC, which prevents the flow of sodium ions back into the cells. A step by step guide is then used to describe the sequence of events that result in mucus which is motile and can be moved by the wafting action of the cilia in healthy individuals. This leads into the section of the lesson which considers the inheritance of cystic fibrosis in an autosomal recessive manner and then focuses on the change in the primary structure of the channel which results from one of over 1500 different gene mutations. Again, the students are guided through the events that lead to the depletion of the apical surface liquid and the cilia being unable to move the viscous mucus. Although the majority of the lesson is described with reference to the gaseous exchange system, the impaired functioning of the digestive system in terms of the blockage of the pancreas and liver secretions is considered and discussed and the students are challenged on their understanding through a range of exam-style questions. All of the questions included in the lesson have mark schemes which are embedded into the PowerPoint and this allows the students to assess their progress. Due to the detailed content of this lesson, it is estimated that it will take in excess of 3 hours of allocated A-level teaching time to cover

Disaccharides are formed from the condensation of two monosaccharides and this lesson describes the formation of maltose, sucrose and lactose. The concise PowerPoint and accompanying question sheet have been designed to cover the third part of points 1.12 & 1.13 of the Pearson Edexcel A-level Biology A specification but also continually links to the previous lesson on monosaccharides when considering the different components of these three disaccharides. The first section of the lesson focuses on a prefix and a suffix so that the students can recognise that the names of the common disaccharides end in -ose. In line with this, a quick quiz round is used to introduce maltose, sucrose and lactose before students are challenged on their prior knowledge as they have to describe how condensation reactions and the formation of glycosidic bonds were involved in the synthesis of each one. The main task of the lesson again challenges the students to recall details of a previous lesson as they have to identify the monomers of each disaccharide when presented with the displayed formula. Time is taken to show how their knowledge of these simple sugars will be important in later topics such as extracellular enzymes, translocation in the phloem and the control of gene expression as exemplified by the Lac Operon. The lesson finishes with two exam-style questions where students have to demonstrate and apply their newly acquired knowledge

This lesson describes the basic structure of mononucleotides and the resulting structural similarities and differences between DNA and RNA. The PowerPoint and accompanying resource have been designed to cover points 2.9 (i) and (ii) of the Edexcel International A-level Biology specification and makes regular links to upcoming lessons which cover DNA replication and protein synthesis. In a lesson in topic 1, the students were introduced to monosaccharides as an example of a monomer and were informed that a nucleotide was another example. In line with this, the start of the lesson challenges them to recognise the key term nucleotide when only the letters U, C and T are shown. The next part of the lesson describes the structure of a DNA nucleotide and an RNA nucleotide so that the pentose sugar and the bases adenine, cytosine and guanine can be recognised as similarities whilst deoxyribose and ribose and thymine and uracil are seen as the differences. Time is taken to discuss how a phosphodiester bond is formed between adjacent nucleotides and their prior knowledge and understanding of condensation reactions is tested through a series of questions. Students are then introduced to the purine and pyrimidine bases and this leads into the description of the double-helical structure of DNA and the hydrogen bonds between complementary bases. The final section of the lesson describes the structure of mRNA, tRNA and rRNA and students are challenged to explain why this single stranded polynucleotide is shorter than DNA In addition to the current understanding and prior knowledge checks, a number of quiz rounds have been written into the lesson to introduce key terms in a fun and memorable way and the final round acts as a final check on the structures of DNA and RNA.

This lesson explains the meaning of gene, allele, genotype, phenotype, recessive, dominant, codominance, homozygote and heterozygote. The engaging PowerPoint and accompanying resources have been designed to cover specification point 2.15 (i) of the Edexcel International A-level Biology but also covers the meaning of genome, gene locus, homologous chromosomes, multiple alleles, autosomes and sex chromosomes as a recognition of these will be useful for upcoming lessons. 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 fully-resourced lesson describes how cells become specialised through differential gene expression. The PowerPoint and accompanying resources have been designed to cover the details of point 3.19 of the Edexcel International A-level Biology specification. 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 2, 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. The final section of the lesson looks at one further example with oestrogen and the ER receptor and explains how the binding of this chemical results in the release of the inhibitor and the production of active mRNA.

This detailed and fully-resourced lesson describes the relationship between the structure and function of glycogen and amylose and amylopectin as components of starch. The engaging PowerPoint and accompanying resources have been designed to cover the fourth part of points 1.2 & 1.4 of the Edexcel International A-level Biology specification and links are continuously made to the previous lessons in this topic where the monosaccharides and disaccharides were introduced. The lesson begins with the CARBOHYDRATE WALL where students have to use their prior knowledge to collect the 9 carbohydrates on show into 3 groups. This results in glycogen, starch and cellulose being grouped together as polysaccharides and the structure and roles of the first two are covered over the course of the lesson. Cellulose is covered in a lesson in topic 4. Students will learn how key structural features like the 1 - 4 and 1 - 6 glycosidic bonds and the hydrogen bonds dictate whether the polysaccharide chain is branched or unbranched and also allows for spiralling. Following the description of the structure of glycogen, students are challenged to design an exam question in the form of a comparison table so that it can be completed as the lesson progresses and they learn more about starch. This includes a split in the starch section of the table so that the differing structures and properties of amylose and amylopectin can be considered. The importance of the compact structure for storage is discussed as well as the branched chains of amylopectin acting as quick source of energy when it is needed. The lesson concludes with a question and answer section that guides the students when answering a question about the importance of the lower solubility of the polysaccharides when compared to the monosaccharides.

This clear and concise lesson describes the meaning of a gene locus and explains how the inheritance of two or more genes that have loci on the same chromosome demonstrates linkage. The engaging PowerPoint and associated resource have been designed to cover points 3.9 (i) and (ii) of the Edexcel International A-level Biology specification and makes clear links to the upcoming topic of meiosis when describing the effect of crossing over on this linkage This is a topic which can cause confusion for students so time was taken in the design to split the concept into small chunks. There is a clear focus on how the number of original phenotypes and recombinants can be used to determine linkage and suggest how the loci of the two genes compare. Important links to other topics such as crossing over in meiosis are made to enable students to understand how the random formation of the chiasma determines whether new phenotypes will be seen in the offspring or not. Linkage is an important cause of variation and the difference between observed and expected results and this is emphasised on a number of occasions. The main task of the lesson acts as an understanding check where students are challenged to analyse a set of results involving the inheritance of the ABO blood group gene and the nail-patella syndrome gene to determine whether they have loci on the same chromosome and if so, how close their loci would appear to be.

This fully-resourced lesson describes the relationship between the structure of monosaccharides and their roles in living organisms. The detailed and engaging PowerPoint and accompanying resources have been designed to cover the second part of points 1.12 & 1.13 of the Pearson Edexcel A-level Biology A specification and looks at alpha-glucose, galactose, fructose, deoxyribose and ribose. The lesson begins with a made-up round of the quiz show POINTLESS, where students have to try to identify four answers to do with carbohydrates. In doing so, they will learn or recall that these molecules are made from carbon, hydrogen and oxygen, that they are a source of energy which can sometimes be rightly or wrongly associated with obesity and that the names of the three main groups is derived from the Greek word sakkharon. Using the molecular formula of glucose as a guide, students will be given the general formula for the monosaccharides and will learn that deoxyribose is an exception to the rule that the number of carbon and oxygen atoms are equal. Moving forwards, students have to study the displayed formula of glucose for two minutes without being able to note anything down before they are challenged to recreate what they saw in a test of their observational skills. At this point of the lesson, the idea of numbering the carbons is introduced so that the different glycosidic bonds can be understood in an upcoming lesson as well as the recognition of the different isomers of glucose. The difference between alpha and beta-glucose is provided but students do not need to consider the beta form until topic 4. The remainder of the lesson focuses on the roles of the monosaccharides and the final task involves a series of application questions where the students are challenged to suggest why ribose could be considered important for active transport and muscle contraction

This fully-resourced lesson describes how it’s possible for 1 gene to give rise to multiple proteins as a result of post-transcriptional changes to mRNA. The detailed PowerPoint and accompanying resources have been primarily designed to cover point 6.10 of the Pearson Edexcel A-level Biology A specification but also checks on the students knowledge and understanding of the lac operon as covered in topic 3. 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 2 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 detailed and fully-resourced lesson describes the structure and properties of the cell membrane, focusing on the phospholipid bilayer and membrane proteins. The PowerPoint and accompanying worksheets have been designed to cover point 2.2 of the Pearson Edexcel A-level Biology A specification and makes links to the fluid mosaic model which is covered in greater detail in the next lesson. Students were introduced to triglycerides in topic 1 and the start of this lesson challenges them to recall the structure of this lipid to identify the shared features of a phospholipid. This introduces the structure of this macromolecule as a glycerol molecule, two fatty acids and a phosphate group. Time is taken to look at the differing properties of the phosphate group and the fatty acid tails so that students become comfortable with the terms hydrophobic and hydrophilic. At this point, the class is given an opportunity to discuss how the phospholipids are arranged when both the inside and outside of the cell contains an aqueous solution and the phospholipid bilayer as the fabric of the membrane is subsequently met. 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 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. It is at this point of the lesson that students will meet the fluid mosaic model and will begin to understand how this describes the dynamic nature of the membrane as well as explaining the interaction with the environment. 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 detailed lesson describes how the crossing over of alleles and the independent assortment in meiosis contribute to genetic variation. The PowerPoint and accompanying resource have been designed to cover specification point 3.10 of the Edexcel International A-level Biology specification and includes describes how the fertilisation of the haploid gametes that were formed by meiosis increases variation further. In order to understand how the events of meiosis like crossing over and random assortment and independent segregation can lead to variation, students need to be clear in their understanding that DNA replication in interphase results in homologous chromosomes as pairs of sister chromatids. Therefore the beginning of the lesson focuses on the chromosomes in the parent cell and this first part of the cycle and students will be introduced to non-sister chromatids and the fact that they may contain different alleles which is important for the exchange that occurs during crossing over. Time is taken to go through this event in prophase I in a step by step guide so that the students can recognise that the result can be new combinations of alleles that were not present in the parent cell. Moving forwards, the lesson explores how the independent segregation of chromosomes and chromatids during anaphase I and II results in genetically different gametes. The final part of the lesson looks at the use of a mathematical expression to calculate the possible combinations of alleles in gametes as well as in a zygote following the random fertilisation of haploid gametes. Understanding and prior knowledge checks are interspersed throughout the lesson as well as a series of exam questions which challenge the students to apply their knowledge to potentially unfamiliar situations.

This fully-resourced lesson describes the role of mitosis and the cell cycle in producing identical cells for growth and asexual reproduction. The detailed PowerPoint and accompanying differentiated resources have been designed to cover point 3.10 of the Pearson Edexcel A-level Biology A specification In the previous lesson covering meiosis (3.9), students were introduced to the different phases and structures involved in the cycle so this lesson builds on that by providing greater detail of the key events in each phase. Beginning with a focus on interphase, the importance of DNA replication is explained so that students can initially recognise that there are pairs of identical sister chromatids and then can understand how they are separated later in the cycle. A quiz competition has been written into the lesson and this runs throughout, challenging the students to identify the quantity of DNA in the cell (in terms of n) at different points of the cycle. The main part of the lesson focuses on prophase, metaphase, anaphase and telophase and describes how the chromosomes behave in these stages. Students will understand how the cytoplasmic division that occurs in cytokinesis results in the production of genetically identical daughter cells. This leads into a series of understanding and application questions where students have to identify the various roles of mitosis in living organisms as well as tackling a Maths in a Biology context question. The lesson concludes with a final round of MITOSIS SNAP where they only shout out this word when a match is seen between the name of a phase, an event and a picture.

This detailed lesson describes osmosis as the movement of free water molecules through a partially permeable membrane, down the water potential gradient. The engaging PowerPoint and accompanying resources have been designed to cover the details of specification point 2.4 of the Edexcel International A-level Biology specification and also describes the effect of solutions of different water potentials on suspended animal and plant cells. It’s likely that students will have used the term concentration in their osmosis definitions at iGCSE, 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, down 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 the structure of the mammalian lung is adapted for rapid gaseous exchange. The engaging PowerPoint has been designed to cover point 2.1 (iii) of the Edexcel International A-level Biology 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 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 the air takes on moving into the lungs.

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 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 describes the ultrastructure of plant cells and includes the cell walls, chloroplasts, amyloplasts, vacuole, tonoplast, plasmodesmata, pits and middle lamella. The detailed PowerPoint and accompanying resources have been designed to cover point 4.7 of the Pearson Edexcel A-level Biology specification and also compares this structure against animal cells that was covered at the beginning of topic 3. 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.