This fully-resourced lesson describes how rod cells in the mammalian retina detect stimuli to allow vision in low light intensity. The detailed PowerPoint and accompanying resources have been designed to cover the second part of point 8.5 of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification and includes reference to the roles of rhodopsin, opsin, retinal, sodium ions, cation channels and hyperpolarisation in the formation of action potentials in the optic neurones. It is likely that students will be aware that the human retina contains rod and cone cells, so this lesson builds on that knowledge and adds the detail needed at this level. Students will discover that the optical pigment in rod cells is rhodopsin and that the bleaching of this into retinal and opsin results in a cascade of events that allows an action potential to be initiated along the optic nerve. Time is taken to go through the events that occur in the dark and then the students are challenged to use this as a guide when explaining how the events differ in the light. Key terms like depolarisation and hyperpolarisation, that were met earlier in topic 8, are used to explain the changes in membrane potential and the resulting effect on the connection with the bipolar and ganglion cells is then described.

This lesson describes the extracellular action of peptide hormones and the role played by steroid hormones in binding to DNA transcription factors. The detailed PowerPoint and accompanying resources have been designed to cover point 7.22 of the Edexcel International A-level Biology specification and focuses on the differing effects of these two types of hormones on their target cells Students should have a base knowledge of the endocrine system from GCSE so this lesson has been planned to build on that knowledge and to add the detail needed at this level. The lesson begins by challenging this knowledge to check that they understand that endocrine glands secrete these hormones directly into the blood. Students will learn that most of the secreted hormones are peptide (or protein) hormones and a series of exam-style questions are used to challenge them on their recall of the structure of insulin as well as to apply their knowledge to questions about glucagon. Moving forwards, the students are reminded that hormones have target cells that have specific receptor sites on their membrane. The relationship between a peptide hormone as a first messenger and a second messenger on the inside of the cell is covered in detail in an upcoming lesson but students are briefly introduced to G proteins and cyclic AMP so they are prepared. The rest of the lesson focuses on steroid hormones and specifically their ability to pass through the membrane of a cell and to bind to transcription factors, as exemplified by oestrogen. Students covered transcription and the control of gene expression in topics 2 and 3 so the final tasks challenge their recall of these concepts

This fully-resourced lesson describes the relationship between the properties and functions of the fibrous proteins, collagen, keratin and elastin. The detailed PowerPoint and accompanying resources have been designed to cover point 2.1.2 (o) of the OCR A-level Biology A specification but also make links to upcoming topics such as blood vessel structure and the immune system as well as constantly challenging students on their knowledge of proteins from earlier in this module. The lesson begins by challenging the students to recognise 7 structures found in animals from their descriptions and once they’ve written feathers, cartilage, bones, arteries, tendons, callus and skin into the right places, they will reveal the term fibrous and learn that these types of protein are found in these structures. Using their knowledge of the properties of globular proteins, they will learn that the insolubility of fibrous proteins allows them to form fibres, which perform structural functions. The rest of the lesson focuses on the functions of collagen, keratin and elastin and time is taken to discuss the key details and to make links to future topics so that students can recognise the importance of cross-modular based answers. A series of exam-style questions are used to challenge their knowledge of protein structure as well as their ability to apply their knowledge to an unfamiliar situation when learning that elastin is found in the walls of the urinary bladder. All of the questions have mark schemes embedded into the PowerPoint to allow them to immediately assess their understanding. This lesson has been specifically planned to tie in with the previous lesson on globular proteins as well as the one preceding that on the structures of proteins

This lesson introduces the key inorganic ions that are involved in biological processes and includes cations and anions. The engaging PowerPoint and accompanying resources have been designed to cover point 2.1.2 § of the OCR A-level Biology A specification but also makes links to topics in upcoming modules such as respiration, photosynthesis and neuronal communication. The roles of the following ions are covered in this lesson: phosphate nitrate chloride hydroxide hydrogencarbonate hydrogen ammonium sodium potassium calcium Extra time is taken during the lesson to describe how these ions are involved in the transport of carbon dioxide, the conduction of nervous impulses and blood clotting as well as other processes and a number of quiz competitions have been included to introduce key terms in a fun and memorable way

This fully-resourced revision lesson uses a range of activities to challenge the students on their knowledge of proteins from module 2.1.2. The engaging PowerPoint and accompanying resources have been designed to test the intricate details of specification points 2.1.2 (k), (l), (m), (n), (o) & (q) The range of activities include exam-style questions with displayed mark schemes, understanding checks and quick quiz competitions that will engage and motivate the students whilst they assess their understanding of this topic. The following concepts are tested during this lesson: The general structure of an amino acid The formation of dipeptides and polypeptides through condensation reactions The primary, secondary, tertiary and quaternary structure of a protein Biological examples of proteins and their specific actions (e.g. antibodies, enzymes, peptide hormones) The biuret test for proteins Time has been taken in the planning to make links to topics in upcoming modules such as the genetic code (2.1.3) and intracellular enzymes (2.1.4)

This fully-resourced lesson describes the primary non-specific defences against pathogens in animals. The engaging and detailed PowerPoint and accompanying resources have been designed to cover point 4.1.1 (d) of the OCR A-level Biology A specification and describes the following defences: skin key steps of the blood clotting process release of histamine in the inflammatory response expulsive reflexes mucous membranes There are clear links to topics in modules 2 and 3 in each of these defences so time is taken to consider these during the descriptions. For example, the presence of keratin in the cytoplasm of the skin cells allows the student knowledge of the properties of this fibrous protein to be checked. Other topics that are revisited during this lesson include protein structure, formation of tissue fluid, key terminology and roles of inorganic ions in biological processes. There is also a section of the lesson which refers to the genetics behind haemophilia and students are challenged to apply knowledge to an unfamiliar situation. This will prepare them for this topic when covered in module 6.1.2 All of the exam-style questions and tasks have mark schemes that are embedded in the PowerPoint and a number of them have been differentiated to allow students of differing abilities to access the work.

This lesson describes the structure and functions of the adrenal glands, and includes the hormones secreted by the cortex and the medulla. The detailed PowerPoint and accompanying resources have been designed to cover point 5.1.4 (b) of the OCR A-level Biology A specification This lesson has been planned to closely tie in with the previous lesson on endocrine communication, and specifically the modes of action of peptide and steroid hormones. At the start of the lesson, the students have to use the knowledge acquired in this last lesson to reveal the key term cortex and this leads into the description of the structure of the adrenal glands in terms of the outer region and the inner region known as the medulla. The main part of the lesson focuses on the range of physiological responses of the organs to the release of adrenaline. Beginning with glycogenolysis, the need for adrenaline to bind to adrenergic receptors is described including the activation of cyclic AMP. A quiz competition is used to introduce other responses including lipolysis, vasodilation, bronchodilation and an increase in stroke volume. Links to previous topics are made throughout the lesson and students are challenged on their knowledge of heart structure and polysaccharides. The final part of the lesson introduces the three zones of the adrenal cortex and the steroid hormones that they produce along with their functions. Once again, a series of exam-style questions are used to challenge their ability to apply their understanding to an unfamiliar situation and to make biological links and the mark schemes are embedded in the PowerPoint.

This lesson explains how negative feedback control maintains systems within narrow limits and uses biological examples to describe the meaning of positive feedback. The PowerPoint and accompanying resources have been designed to cover points 7.11 (i) and (ii) of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification but have been planned to provide important details for upcoming topics such as the importance of homeostasis during exercise and the depolarisation of a neurone. The normal ranges for blood glucose concentration, blood pH and body temperature are introduced at the start of the lesson to allow students to recognise that these aspects have to be maintained within narrow limits. A series of exam-style questions then challenge their recall of knowledge from topics 1 - 6 as well as earlier in topic 7 to explain why it’s important that each of these aspects is maintained within these limits. The students were introduced to homeostasis at GCSE, so this process is revisited and discussed, so that students are prepared for an upcoming lesson on exercise, as well as for the next part of the lesson on negative feedback control. Students will learn how this form of control reverses the original change and biological examples are used to emphasise the importance of this system for restoring levels to the limits (and the optimum). The remainder of the lesson explains how positive feedback differs from negative feedback as it increases the original change and the role of oxytocin in birth and the movement of sodium ions into a neurone are used to exemplify the action of this control system.

This lesson describes the classification system, focusing on the biological classification of a species and the 7 taxa found above this lowest taxon. The engaging PowerPoint and accompanying resource have been designed to cover point 4.6 (i) of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification and also describes the binomial naming system which uses the genus and species. The lesson also contains links to upcoming lessons where molecular phylogeny is described and the three-domain system is covered in greater detail with a focus on the results of Carl Woese’s rRNA study The lesson begins by looking at the meaning of a population in Biology so that the term species can be introduced. A hinny, which is the hybrid offspring of a horse and a donkey, is used to explain how these two organisms must be members of different species because they are unable to produce fertile offspring. Moving forwards, students will learn that classification is a means of organising the variety of life based on relationships between organisms using differences and similarities in phenotypes and in genotypes and is built around the species concept and that in the modern-day classification hierarchy, species is the lowest taxon. A quiz runs throughout the lesson and this particular round will engage the students whilst they learn (or recall) the names of the other 7 taxa and the horse and the donkey from the earlier example are used to complete the hierarchy. Students will understand that the binomial naming system was introduced by Carl Linnaeus to provide a universal name for each species and they will be challenged to apply their knowledge by completing a hierarchy for a modern-day human, by spotting the correct name for an unfamiliar organism and finally by suggesting advantages of this system.

This lesson describes classification as a means of organising the variety of life based on relationships between organisms. The engaging PowerPoint and accompanying resource have been designed to cover point 4.14 (i) of the Edexcel International A-level Biology specification and focuses on the classification hierarchy where species is the lowest taxon but also describes the binomial naming system which uses the genus and species. The lesson also contains links to the next lesson where molecular phylogeny is described and the three-domain system is covered in greater detail with a focus on the results of Carl Woese’s rRNA study The lesson begins by looking at the meaning of a population in Biology so that the term species can be introduced. A hinny, which is the hybrid offspring of a horse and a donkey, is used to explain how these two organisms must be members of different species because they are unable to produce fertile offspring. Moving forwards, students will learn that classification is a means of organising the variety of life based on relationships between organisms using differences and similarities in phenotypes and in genotypes and is built around the species concept and that in the modern-day classification hierarchy, species is the lowest taxon. A quiz runs throughout the lesson and this particular round will engage the students whilst they learn (or recall) the names of the other 7 taxa and the horse and the donkey from the earlier example are used to complete the hierarchy. Students will understand that the binomial naming system was introduced by Carl Linnaeus to provide a universal name for each species and they will be challenged to apply their knowledge by completing a hierarchy for a modern-day human, by spotting the correct name for an unfamiliar organism and finally by suggesting advantages of this system.

This lesson describes the evidence that led to the three-domain model of classification as an alternative to the five-kingdom model. The detailed PowerPoint and accompanying resources have been designed to cover point 3.1 (vii) of the Edexcel A-level Biology B specification and focuses on Carl Woese’s detailed study of the ribosomal RNA gene and the need for this evidence to be validated by the scientific community The lesson begins with an introduction of Woese and goes on to describe how he is most famous for his definition of the Archaea as a new domain of life. Students were introduced to domains and the other classification taxa in a lesson at the start of this topic, so their recall of this knowledge is continually tested and built upon as details are added. Students will discover the key differences between Archaea and Bacteria that led to the splitting of the prokaryotae kingdom and the addition of this higher classification rank and will understand that it wasn’t until 13 years after the discovery that it was adopted. Moving forwards, the rest of the lesson describes how molecular phylogeny uses other molecules that can be compared between species for classification purposes. One of these is a protein called cytochrome which is involved in respiration and can be compared in terms of primary structure to determine relationships. At this point in the lesson, the students are also tested on their knowledge of the nature of the genetic code (as covered in topic 1) and have to explain how mutations to DNA can also be used for comparative purposes.

This lesson explains that biodiversity is considered at three levels and describes how the Simpson’s Index of Diversity is used to calculate the biodiversity within a habitat. The engaging and detailed PowerPoint and accompanying resources have been designed to cover points 18.1 (a, b & f) of the CIE A-level Biology specification and also covers the meaning of ecosystems and niche as well as some other important ecological terms that are related such as abiotic factors and population. A quiz competition called BIOLOGICAL TERMINOLOGY SNAP runs throughout the lesson and has been included to engage the students whilst challenging them to recognise key terms from their definitions. This quiz will introduce species, ecosystems, biodiversity, endemic, heterozygote, distribution and natural selection and each of these terms is put into context once introduced. A series of exam-style questions to challenge the students to explain how the distribution of fish is affected by abiotic factors in an ecosystem. Once biodiversity is revealed through the quiz competition, the students will learn that they need to consider biodiversity within a habitat, within a species and within different habitats so that they can be compared. The rest of the lesson uses step by step guides, discussion points and selected tasks to demonstrate how to determine species richness and the Simpson’s index of diversity. The heterozygosity index is also introduced as a means to consider genetic variation. Students are challenged with a range of exam-style questions where they have to apply their knowledge and all mark schemes are displayed and clearly explained within the PowerPoint to allow students to assess their understanding and address any misconceptions if they arise This is a detailed lesson with a lot of tasks (some of which are differentiated), so it is estimated that it will take in excess of 2 hours of allocated A-level teaching time to cover all of the content

This lesson describes the characteristic features of the three domains and explains why viruses are not included in this classification. The PowerPoint and accompanying resources have been primarily designed to cover points 18.2 (b) & 18.2 (d) of the CIE A-level Biology specification but also contains tasks that challenge the students on their knowledge of taxonomic hierarchy from this topic and the features of virus from topic 1. The lesson begins with an introduction of the microbiologist Carl Woese and goes on to describe how he is most famous for his definition of the Archaea as a new domain of life. Students were introduced to domains and the other classification taxa in the last lesson, so their recall of this knowledge is continually tested and built upon as details are added. Students will discover the key differences between Archaea and Bacteria that led to the splitting of the prokaryotae kingdom and the addition of this higher classification rank and will understand that it wasn’t until 13 years after the discovery that it was adopted. Moving forwards, the rest of the lesson explains why viruses are not included in this classification and outlines how they are classified, according to the ICTV, through the type of nucleic acid they contain and whether this is single-stranded or double-stranded