This lesson describes the main stages of meiosis, focusing on the events which contribute to genetic variation and explains its significance in life cycles. The detailed PowerPoint and accompanying resources have been designed to cover points 2.1.6 (f) & (g) of the OCR A-level Biology A specification and includes description of crossing over, independent assortment, independent segregation and the production of haploid gametes
In order to understand how the events of meiosis like crossing over and independent 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 assortment and segregation of chromosomes and chromatids during metaphase I and II and anaphase I and II respectively results in genetically different gametes. The key events of all of the 8 phases are described and there is a focus on key terminology to ensure that students are able to describe genetic structures in the correct context. 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-style questions which challenge the students to apply their knowledge to potentially unfamiliar situations.
This lesson has been specifically planned to lead on from the previous two lessons on the cell cycle and the main stages of mitosis and constant references are made throughout to encourage students to make links and also to highlight the differences between the two types of nuclear division
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Enzymes, biological membranes & cell division (OCR A-level Biology A)
This lesson bundle has been formed from the 13 detailed lesson PowerPoints and their accompanying resources that have been uploaded to cover a lot of the content in modules 2.1.4, 2.1.5 and 2.1.6 of the OCR A-level Biology A specification. Each lesson contains a wide range of tasks, which include exam-style questions (with mark schemes), guided discussion points, and quick quiz competitions, that will engage and motivate the students whilst covering the following specification points: Module 2.1.4: Enzymes * The role of enzymes in catalysing reactions that affect metabolism at a cellular and whole organism level * The role of enzymes in catalysing both intracellular and extracellular reactions * The mechanism of enzyme action * The effect of pH on enzyme activity * The effect of temperature on enzyme activity * The calculation of the temperature coefficient * The effect of enzyme and substrate concentration on enzyme activity * The need for coenzymes, cofactors and prosthetic groups in some enzyme-controlled reactions Module 2.1.5: Biological membranes * The fluid mosaic model of membrane structure and the roles of its components * Simple and facilitated diffusion as forms of passive transport * Active transport, endocytosis and exocytosis as processes requiring ATP as an immediate source of energy * The movement of water across membranes by osmosis and the effects that solutions of different water potential can have on plant and animal cells Module 2.1.6: Cell division, cell diversity and cellular organisation * The cell cycle * How the cell cycle is regulated * The main stages of mitosis * The significance of mitosis in life cycles * The significance of meiosis in life cycles * The main stages of meiosis * How cells of multicellular organisms are specialised for particular functions * The organisation of cells into tissues, organs and organ systems * The production of erythrocytes and neutrophils from stem cells in bone marrow If you would like to sample the quality of the lessons in this bundle, then download the following lessons as they have been uploaded for free: * The roles of enzymes and mechanism of action * Simple and facilitated diffusion * Cell specialisation and organisation
£20.00
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Module 2.1.6: Cell division, cell diversity and organisation (OCR A-level Biology A)
This lesson bundle contains 4 detailed lesson PowerPoints, which along with their accompanying resources have been designed to cover the majority of the content in module 2.1.6 of the OCR A-level Biology A specification. The lessons have been planned at length and include exam-style questions that will challenge the students on their current understanding, prior knowledge checks to encourage students to make links to previously covered topics, guided discussion points and quick quiz competitions to introduce memorable terms and values. The following specification points are covered by the resources in this bundle: * The cell cycle * How the cell cycle is regulated * The main stages of mitosis * The significance of mitosis in life cycles * The significance of meiosis in life cycles * The main stages of meiosis * How cells of multicellular organisms are specialised for particular functions * The organisation of cells into tissues, organs and organ systems * Stem cells as a renewing source of undifferentiated cells * The production of erythrocytes and neutrophils derived from stem cells in bone marrow If you would like to sample the quality of the lessons in this bundle, then download the cell specialisation and organisation lesson as this has been uploaded for free
£7.00
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