This engaging and fully-resourced lesson looks at how genetic drift can arise after a genetic bottleneck or as a result of the Founder effect. The detailed PowerPoint and accompanying resources have been designed to cover the second part of point 6.1.2 (e) of the OCR A-level Biology A specification which states that students should be able to demonstrate and apply an understanding of the factors that affect the evolution of a species. 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 lesson has been designed to tie in with another uploaded lesson on types of selection which is part of this specification point

This fully-resourced lesson looks at the contribution of environmental and genetic factors to phenotypic variation. The engaging PowerPoint and accompanying worksheets have been designed to cover point 6.1.2 (a) of the OCR A-level Biology A specification which states that students should be able to demonstrate and apply an understanding of how mutations and meiosis and the lack of availability of ions can cause variation within a species. Students are challenged at the start of the lesson to recognise the terms phenotype and species from their definitions in order to begin a discussion on the causes of the phenotypic variation within a species. Moving forwards, students will recall that mutations are the primary source of genetic variation and time is taken to look at the effect of gene and chromosome mutations. Gene mutations were covered earlier in module 6 so these tasks act as a prior knowledge check as students have to recognise the different types of gene mutations and explain their effects on the primary structure with reference to the genetic code. These prior knowledge checks are found throughout the lesson and challenge the knowledge of other topics that include photosynthesis and meiosis. The karyotype of an individual who has Down syndrome is used to introduce chromosome mutations and students will be introduced to the different types, with a focus on non-disjunction. The key events of meiosis that produce variation (crossing over and independent assortment) are explored and students will be given a mathematical formula to use to calculate the number of chromosome combinations in gametes and in the resulting zygote. The final part of the lesson looks at chlorosis and how an environmental factor can prevent the express of a gene. If you would like a lesson that goes into chromosome mutations in even greater detail, please search for the uploaded lesson on that topic which complements this lesson

This fully-resourced lesson focuses on the events of meiosis which specifically contribute to genetic variation. The detailed PowerPoint and accompanying resources have been designed to cover the 4th and final part of point 4.3 of the AQA A-level Biology specification which states that students should be able to describe how meiosis produces daughter cells that are genetically different from each other. 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. Due to the detail of this lesson, it is estimated that this will take about 2 hours of A-level teaching time to deliver

This lesson focuses on the degenerate nature of the genetic code and explains how a mutation may not result in a change to the sequence of amino acids. The PowerPoint has been designed to cover the first part of point 4.3 of the AQA A-level Biology specification and it makes links to the upcoming lesson on gene mutations. The lesson begins by introducing the terms near universal and non-overlapping in addition to degenerate. A quick quiz competition is used to generate the number 20 so that the students can learn that there are 20 proteinogenic amino acids in the genetic code. This leads into a challenge, where they have to use their prior knowledge of DNA to calculate the number of different DNA triplets (64) and the mismatch in number is then discussed and related back to the lesson topic. Moving forwards, base substitutions and base deletions are briefly introduced so that they can see how although one substitution can change the primary structure, another will change the codon but not the encoded amino acid. The lesson concludes with a brief look at the non-overlapping nature of the code so that the impact of a base deletion (or insertion) can be understood when covered in greater detail in topic 8. This lesson has been specifically designed to tie in with the other lessons from topic 4.3 on gene mutations, chromosome mutations and meiosis.

This fully-resourced lesson explores how new species arise when changes in the gene pool of two populations prevents members from interbreeding and producing fertile offspring. The engaging PowerPoint and accompanying resources have been designed to cover the fifth part of point 7.3 of the AQA A-level Biology specification which states that students should be able to describe allopatric and sympatric speciation. The lesson begins by using the example of a hinny, which is the hybrid offspring of a horse and a donkey, to challenge students to recall the biological classification of a species. Moving forwards, students are introduced to the idea of speciation and the key components of this process, such as isolation and selection pressures, are covered and discussed in detail. Understanding and prior knowledge checks are included throughout the lesson to allow the students to not only assess their progress against the current topic but also to make links to earlier topics in the specification. Time is taken to look at the details of allopatric speciation and how the different mutations that arise in the isolated populations and genetic drift will lead to genetic changes. The example of allopatric speciation in wrasse fish because of the isthmus of Panama is used to allow the students to visualise this process. The final part of the lesson considers sympatric speciation and again a wide variety of tasks are used to enable a deep understanding to be developed.

This engaging REVISION LESSON has been designed to cover the content of topic 13 (Photosynthesis) of the CIE International A-level Biology specification. Filled with a wide range of activities, that include exam questions with explanations, quick tasks and quiz competitions, the students will be motivated whilst they assess their ability to apply their knowledge. Due to the obvious importance of this reaction, assessment questions are extremely common and so a deep understanding of this topic is key to success and the lesson has been designed to cover the important ideas. The following sub-topics have received particular attention in this lesson: Photophosphorylation An outline of cyclic and non-cyclic photophosphorylation Photolysis of water The light dependent reaction The structure of the chloroplast and the site of the different reactions The Calvin cycle The limiting factors of photosynthesis Investigating the effect of light intensity using DCPIP as a redox indicator and a Hill suspension The effect of temperature on the rate There is a focus on terminology throughout the lesson so that students are comfortable with the terms that will be encountered in exam questions. Revision lessons on the other topics of the specification are uploaded so please take a moment to look at those too

This fully-resourced lesson focuses on the role of meiosis in ensuring genetic variation through the production of non-identical gametes. The detailed PowerPoint and accompanying resource have been designed to cover point 3.9 of the Pearson Edexcel A-level Biology (Salters Nuffield) specification which states that students should be able to describe how crossing over and independent assortment result in genetically unidentical daughter cells. 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 covers the meaning of the 9 genetic terms that are detailed in point 2.13 (i) of the Pearson Edexcel A-level Biology (Salters Nuffield) specification as well as four other key terms which will need to be used later in topic 2, 3 and 8. In the following lessons, students are expected to be able to demonstrate and apply their knowledge and understanding of genetic diagrams and phenotypic ratios to show patterns of inheritance and this is only possible with a clear understanding of the genetic terminology that will be used in related exam questions. As some of these terms were met at GCSE, this lesson has been designed to 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 act as an understanding check. The 13 terms are genome, gene, chromosome, gene locus, homologous chromosomes, alleles, dominant, recessive, genotype, phenotype, homozygotes and heterozygotes

This fully-resourced lesson is clear and concise and has been written to explain 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 point 3.8 (i and ii) of the Pearson Edexcel A-level Biology (Salters Nuffield) specification which states that students should know the meaning of a gene locus and understand the linkage of genes on a chromosome. 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 is a fully-resourced lesson which looks at the inheritance of genes that are carried on the sex chromosomes in sex-linkage. Students will explore sex-linked diseases in humans and then are challenged to apply their knowledge to examples in other animals. The detailed PowerPoint and associated resources have been designed to cover the second part of point 3.8 (ii) of the Pearson Edexcel A-level Biology (Salters Nuffield) specification which states that students should understand sex-linkage. 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. 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 apply their knowledge to a question about chickens and how the rate of feather production in chicks can be used to determine gender.

This lesson focuses on the nature of the genetic code and specifically focuses on the degenerate nature to make a link to gene mutations which is covered later in topic 2. The PowerPoint has been designed to cover point 2.7 of the Pearson Edexcel A-level Biology (Salters Nuffield) specification which states that students should understand how the descriptive terms triplet code, degenerate and non-overlapping relate to the genetic code. The lesson begins by introducing the terms near universal and non-overlapping in addition to degenerate. A quick quiz competition is used to generate the number 20 so that the students can learn that there are 20 proteinogenic amino acids in the genetic code. This leads into a challenge, where they have to use their prior knowledge of DNA to calculate the number of different DNA triplets (64) and the mismatch in number is then discussed and related back to the lesson topic. Moving forwards, substitutions and deletions are briefly introduced so that they can see how although one substitution can change the primary structure, another will change the codon but not the encoded amino acid. The lesson concludes with a brief look at the non-overlapping nature of the code so that the impact of a base deletion can be understood when covered in greater detail with cystic fibrosis

This fully-resourced lesson has been designed to cover point 8.4 of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification that states that students should know the structures and function of synapses in nerve impulse transmission. The majority of the lesson uses the cholinergic synapse as the example but other neurotransmitters are considered to provide the students with a wider view of this topic and to make links to specification point 8.15 The lesson begins by using a version of the WALL (as shown in the cover image) which asks the students to group 12 words into three groups of 4. Not only will this challenge their prior knowledge from topics earlier in this module but it will also lead to the discovery of four of the structures that are found in a synapse. Moving forwards, students are introduced to aectylcholine as the neurotransmitter involved at cholinergic synapses and they will start to add labels to the structures found in the pre-synaptic bulb. Time is taken to focus on certain structures such as the voltage gated channels as these types of channel were met previously when looking at the depolarisation of a neurone. There is plenty of challenge and discovery as students are pushed to explain why organelles like mitochondria would be found in large numbers in the bulb. With this process being a cascade of events, a bullet point format is used to ensure that the key content is taken in by the students and again key points like exocytosis and the action of acetylcholinesterase are discussed further. The final part of the lesson challenges the application aspect of the specification as students are introduced to unfamiliar situations in terms of synapses with new drugs like MDMA and are asked to work out and explain how these affect the nervous transmission. Understanding checks and prior knowledge checks are included throughout the lesson so that students can not only assess their progress against the current topic but also see whether they can make links to earlier topics.

This detailed lesson looks at the structure and function of the motor neurones that form the autonomic nervous system and is responsible for automatic responses. The engaging PowerPoint and accompanying resource have both been designed to cover the second part of point 5.1.5 (g) of the OCR A-level Biology A specification which states that students should be able to demonstrate and apply their knowledge and understanding of the functional organisation of the motor system into somatic and autonomic systems. Students will discover that this system is further divided into sympathetic and parasympathetic systems to control different aspects of a particular involuntary response. The lesson begins with a focus on the types of effectors that will be connected to the CNS by autonomic motor neurones. Students will learn that effectors which are not under voluntary control such as cardiac muscle, smooth muscle and glands will be innervated by these neurones. Moving forwards, a quick quiz competition is used to introduced ganglia as a structure which connects the two or more neurones involved in the cell signalling between the CNS and the effector. This leads into the discovery of the two divisions and students will begin to recognise the differences between the sympathetic and parasympathetic systems based on function but also structure. The remainder of the lesson looks at the differing effects of these two systems. This lesson has been written to tie in with the lesson on the organisation of the mammalian nervous system which covers the first part of specification point 5.1.5 (g)

This fully-resourced lesson looks at how heart rate is controlled by the cardiovascular control centre in the medulla oblongata. The engaging and detailed PowerPoint and accompanying resources have been designed to cover the first part of point 7.9 (ii) of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification but also ties in well with previously covered topics and provides a good introduction to control systems which are covered later in topic 7 and 8. This lesson begins with a prior knowledge check where students have to identify and correct any errors in a passage about the conduction system of the heart. This allows the SAN to be recalled as this structure play an important role as the effector in this control system. Moving forwards, the three key parts of a control system are recalled as the next part of the lesson will specifically look at the range of sensory receptors, the coordination centre and the effector. Students are introduced to chemoreceptors and baroreceptors and time is taken to ensure that the understanding of the stimuli detected by these receptors is complete and that they recognise the result is the conduction of an impulse along a neurone to the brain. A quick quiz is used to introduce the medulla oblongata as the location of the cardiovascular centre. The communication between this centre and the SAN through the autonomic nervous system can be poorly understood so detailed explanations are provided and the sympathetic and parasympathetic divisions compared. The final task challenges the students to demonstrate and apply their understanding by writing a detailed description of the control and this task has been differentiated three ways to allow differing abilities to access the work

This fully-resourced lesson looks at the detailed structure of a muscle fibre, and focuses on the proteins, bands and zones that are found in the myofibril. The engaging PowerPoint and acccompanying resource have been designed to cover point 7.10 (i) of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification. The lesson begins with an imaginary question from the quiz show POINTLESS, where students have to recognise a range of fields of study. This will reveal myology as the study of muscles so that key terms like myofibril, myofilament and myosin can be introduced. Students should have met these terms as well as actin when learning about the sliding filament theory in topic 7.2, so this acts as a recall. Moving forwards, students will be shown the striated appearance of this muscle so they can recognise that some areas appear dark where both myofilaments are found and others as light as they only contain actin or myosin. A quiz competition is used to introduce the A band, I band and H zone and students then have to use the information given to label a diagram of the myofibril. The final task challenges the students to use their knowledge of the sliding filament theory to recognise which of these bands or zones narrow or stay the same length when muscle is contracted.

This fully-resourced lesson explores how other respiratory substrates, such as lipids and proteins, can be used to produce molecules of ATP. The PowerPoint and accompanying resources have been designed to cover the 7th and final part of point 5.2 of the AQA A-level Biology specification which states that students should know how these substrates enter the Krebs cycle. This lesson has been written to challenge the knowledge of the earlier parts of the topic of respiration and so contains constant prior knowledge checks which come in a range of forms. Students will learn that lipids and proteins can be used as respiratory substrates and will recognise the different ways that they enter the respiratory pathway. Time is taken to look at the beta oxidation pathway and again students are challenged to compare the products of this pathway against that of the Link reaction.

This clear and concise lesson explores the importance of coenzymes in cellular respiration as detailed in point 5.2.2 (f) of the OCR A-level Biology A specification. Students encountered coenzymes in module 2.1.4 as well as looking at the roles of NAD, CoA and FAD whilst learning about glycolysis, the link reaction and Krebs cycle earlier in this module. Therefore this lesson was designed to check on their understanding of the importance of these roles and goes on to explain how the transport of the protons and electrons to the mitochondrial cristae is key for the production of ATP. This lesson has been written to tie in with the other uploaded lessons in module 5.2.2 which include the mitochondria, glycolysis, the link reaction and the Krebs cycle

This fully-resourced lesson explores how glucose as well as the other respiratory substrates, such as lipids and proteins, can enter the respiratory pathway and therefore can be respired to produce molecules of ATP. The engaging PowerPoint and accompanying resources have been designed to cover points 12.1 (f) and (g) of the CIE International A-level Biology specification which states that students should be able to explain the relative energy values of carbohydrates, lipids and proteins and be able to determine respiratory quotients from equations. This lesson has been written to challenge current understanding as well as introduce details of glycolysis, the link reaction and Krebs cycle as these stages have yet to be covered fully. Students will learn that lipids and proteins can be used as respiratory substrates and will recognise the different ways that they enter the respiratory pathway. A quick quiz competition is used to introduce the relative energy value for carbohydrates and students are challenged to predict how the values for lipids and proteins will compare. As a result, students will recognise that a greater number of hydrogen atoms results in a greater availability of protons to form the proton gradient to fuel the production of ATP. The rest of the lesson focuses on the calculation of the respiratory quotient and time is taken to look at how the result can be interpreted to determine which substrates were respired.