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 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 fourth part of point 7.3 of the AQA A-level Biology specification which states that students should be able to explain the importance of genetic drift in causing changes in allele frequency in small populations 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 engaging and fully-resourced lesson looks at the effects of stabilising, directional and disruptive selection as the three main types of selection. The PowerPoint and accompanying resources have been designed to cover the 3rd part of point 7.3 of the AQA A-level Biology 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 method is covered later in topic 7 so this section of the lesson is designed purely to generate changes in numbers of the organisms. Sketch graphs are then constructed to show the changes in the population size in this example. 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 explores how genetic and environmental factors cause phenotypic variation. The engaging PowerPoint and accompanying worksheets have been designed to cover the first part of point 7.3 of the AQA A-level Biology specification which states that students should be able to describe how mutations and meiosis both contribute to genetic variation 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. Just like the majority of parts of this specification point, gene mutations were covered earlier in topic 4 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, meiosis and inorganic ions. 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.

This fully-resourced lesson explores the effect of geographical and reproductive isolation on the evolution of a new species. The engaging PowerPoint and accompanying resources have been designed to cover point 6.1.2 (g) of the OCR A-level Biology A specification which states that students should be able to demonstrate and apply an understanding of the effect of these isolating mechanisms on the evolution of a new species by either allopatric or 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 lesson has been written to tie in with the other uploaded lessons on topic 6.1.2 (patterns of inheritance).

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 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 engaging and fully-resourced lesson looks at examples of stabilising, directional and disruptive selection as the three main types of selection. The PowerPoint and accompanying resources have been designed to cover the 1st part of point 6.1.2 (e) of the OCR A-level Biology specification which states that students should be able to demonstrate and apply an understanding of the factors that affect the evolution of a species. The lesson begins by making a link to a topic from module 4 as the students are challenged to use the mark, release, recapture method to calculate numbers of rabbits with different coloured fur in a particular habitat. Sketch graphs are then constructed to show the changes in the population size in this example. 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 lesson has been designed to tie in with another uploaded lesson on genetic drift which covers the second part of this specification point.

This fully-resourced REVISION lesson has been designed to enable the students to challenge their knowledge of the content of topic 16 (Inherited change) of the CIE A-level Biology specification. The engaging PowerPoint and accompanying differentiated worksheets will motivate the students whilst they assess their understanding of the content and identify any areas which may require further attention. The wide range of activities have been written to cover as much of the topic as possible but the following specification points have been given particular focus: Homologous pairs of chromosomes The meanings of haploid and diploid The behaviour of chromosomes in meiosis Crossing over and random assortment as causes of genetic variation The use of key genetic terminology The use of genetic diagrams to solve problems including autosomal and sex-linkage, dihybrid inheritance and gene interactions The use of the chi-squared test Gene mutations Genetic control of protein production in prokaryotes Gibberellins and how they cause the breakdown of DELLA proteins Due to the extensiveness of this resource, it is likely that it will take a number of lessons to go through all of the activities

This lesson guides students through the use of the chi-squared test to test the significance of differences between observed and expected results. It is fully-resourced with a detailed PowerPoint and differentiated task worksheets that have been designed to cover point 16.2 (d) of the CIE International A-level Biology specification which states that students should be able to use this statistical test to determine the significance. The lesson has been written to include a step-by-step guide that 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 fully-resourced lesson explores how the presence of particular alleles at one locus can mask the expression of alleles at a second locus in gene interactions. The detailed and engaging PowerPoint and associated resources have been designed to cover the part of point 16.2 (b) of the CIE International A-level Biology specification which states that students should be able to use genetic diagrams to solve problems that involve gene interactions. This is a topic which students tend to find difficult, and therefore the lesson was written to split the topic into small chunks where examples of dominant, recessive and complimentary gene interactions are considered, discussed at length and then explained. Understanding checks, in various forms, are included throughout the lesson so that students can assess their progress and any misconceptions are immediately addressed. There are regular links to related topics such as dihybrid inheritance so that students can meet the challenge of interpreting genotypes and link to the different types of interactions

This fully-resourced lesson explores the inheritance of genetic characteristics that involve multiple alleles and codominant alleles. The engaging and detailed PowerPoint and differentiated worksheets have been designed to cover the part of point 16.2 (b) of the CIE International A-level Biology specification which states that students should be able to use genetic diagrams to solve problems which involve codominance and multiple alleles. The main part of the lesson uses the inheritance of the ABO blood groups to demonstrate how the three alleles that are found at the locus on chromosome 9 and the codominance of the A and B alleles affects the phenotypes. Students are guided through the construction of the different genotypes and how to interpret the resulting phenotype. They are challenged to use a partially completed pedigree tree to determine the blood group for some of the family members and to explain how they came to their answer. To further challenge their ability to apply their knowledge, a series of questions about multiple alleles and codominance in animals that are not humans are used. All of the questions are followed by clear, visual mark schemes to allow the students to assess their progress and address any misconceptions

This fully-resourced lesson explores sex-linkage and specifically the inheritance of sex-linked diseases in humans and then challenges the students to apply their knowledge to examples in other animals. The detailed PowerPoint and associated differentiated resources have been designed to cover the part of point 16.2 (b) of the CIE International A-level Biology specification which states that students should be able to use genetic diagrams to solve problems involving 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 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 misconception

This clear and concise lesson explains how the inheritance of two or more genes that have loci on the same chromosome demonstrates autosomal linkage. The engaging PowerPoint and associated resource have been designed to cover the part of point 16.2 (b) of the CIE International A-level Biology specification which states that students should be able to use genetic diagrams to solve problems that involve autosomal 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 lesson guides students through the use of genetic diagrams to solve problems involving monohybrid and dihybrid crosses. The engaging PowerPoint and accompanying worksheets have been designed to cover the part of topic 16.2 (b) of the CIE A-level Biology specification which involves the inheritance of one or two genes As you can see from the cover image, this lesson uses a step by step guide to go through each important stage of drawing the genetic cross. Extra time is taken over step 2 which involves writing out the different possible gametes that a parent can produce. This is the step where students most commonly make mistakes so it is critical that the method is understood. Helpful hints are also given throughout, such as only writing out the different possible gametes in order to avoid creating unnecessary work. Students are shown how to answer an example question so that they can visualise how to set out their work before they are challenged to try two further questions. This first of these is differentiated so that even those students who find this very difficult are able to access the learning. The final question will enable the students to come up with the ratio 9:3:3:1 and they will be shown how they can recognise when this should be the expected ratio as this links to the chi-squared test which is covered later in the topic.