This revision resource includes exam questions, understanding checks and quiz competitions, all of which have been written to motivate and engage the students whilst they assess their understanding of the content found in topic 4 (Biological molecules) of the CIE IGCSE Biology specification for examination in June and November 2020 and 2021. This revision resource contains an engaging PowerPoint (36 slides) and associated worksheets. The range of activities have been designed to cover as much of the Core and Supplement content as possible but the following sub-topics have been given particular attention: List the chemical elements that make up carbohydrates State how starch, glycogen, cellulose, proteins and fats and oils are made from their specific smaller molecules Describe the use of the iodine and Benedicts solution test Explain how the specific sequence of the amino acids in a protein controls the shape and the effect this has on an enzyme and antibodies Describe the structure of DNA Recognise that water is an important solvent which is involved in a large number of roles in the human body In addition, links have been made to other topics such as hormones and organelles so that students can see the importance of making links between Biological topics

This lesson looks at the structure of the DNA that is found in the nucleus, mitochondria and chloroplasts of eukaryotic cells and in prokaryotic cells. Both the engaging PowerPoint and accompanying resources have been designed to cover point 2.1.3 (d)(i) of the OCR A-level Biology A specification. As students will already have some knowledge of this nucleic acid from GCSE and from the earlier A-level topics, the lesson has been written to build on this prior knowledge and then to add key detail. As well as focusing on the differences between the DNA found in these two types of cells which includes the length, shape and association with histones, the various tasks will ensure that students are confident to describe how this double-stranded polynucleotide is held together by hydrogen and phosphodiester bonds. This knowledge of phosphodiester bonds means that specification point 2.1.3 © is also covered during this lesson. These tasks include exam-style questions which challenge the application of knowledge as well as a few quiz competitions to maintain engagement.

This is an engaging and discussion filled lesson which looks at the menstrual cycle and specifically focuses on the interaction of the four hormones in the cycle. This lesson has been designed for GCSE students (ages 14 - 16 in the UK) but is suitable for older students who want a recap on this topic before going into more depth. In order to understand the cycle, it is critical that students know the roles that each of the hormones perform and also can describe how one hormone affects another. The main task of the lesson goes through the steps in the cycle, but challenges the students to use their prior knowledge of the endocrine system to add in the name of the correct hormone. At appropriate points of the lesson, time is taken to relate this topic to others in Biology, such as the use of oestrogen in the contraceptive pill and also hCG as the hormone which is detected by pregnancy tests. Students will know key landmarks in the 28 day cycle and be able to relate this back to the hormones. There are progress checks throughout the lesson but the final part of the lesson involves three understanding checks where students are challenged to apply their knowledge.

This detailed lesson describes the role of the mRNA, tRNA, rRNA and amino acids during the second stage of protein synthesis - translation. Both the PowerPoint and accompanying resources have been designed to cover the second part of point 2.1.3 (g) of the OCR A-level Biology A specification and continually links back to the previous lessons in this module on the structure of DNA and RNA and the genetic code Translation is a topic which is often poorly understood and so this lesson has been written to enable the students to understand how to answer the different types of questions by knowing and including the key details of the structures involved. The lesson begins by challenging the students to consider why it is so important that the amino acids are assembled in the correct order during the formation of the chain. Moving forwards, a quick quiz round called “LOST IN TRANSLATION” is used to check on their prior knowledge of the mRNA strand, the tRNA molecules, the genetic code and the ribosomes. The next task involves a very detailed description of translation that has been divided into 14 statements which the students have to put into the correct order. By giving them a passage that consists of this considerable detail, they can pick out the important parts to use in the next task where they have to answer shorter questions worth between 3 and 4 marks. These types of questions are common in the assessments and by building up through the lesson, their confidence to answer this type should increase. The final two tasks of the lesson involve another quiz, where the teams compete to transcribe and translate in the quickest time before using all that they have absorbed to answer some questions which involve the genetic code and the mRNA codon table

A fully-resourced lesson, designed for GCSE students which includes an engaging and informative lesson presentation (49 slides) and an image, actual and magnification question worksheet. This lesson looks at the key features of light and electron microscopes and guides students through calculating size and magnification. The lesson begins by challenging students to pick out two key terms about microscopes, magnification and resolution, from a group of Scientific words. The understanding of these two terms is critical if students will be able to compare the two types of microscopes so time is taken to go through the definitions and give examples. A number of quick quiz competitions have been written into the lesson to aid the engagement on a topic that some students may not initially consider to be that motivating. These competitions allow key terms such as micrometer and the two types of electron microscope to be introduced in an engaging way. As a result, students will know the numbers that explain why electron microscopes are more advanced than their light counterparts. The remainder of the lesson looks at the units of size which are used in calculation questions and a step by step guide is used to show the students to calculate the actual size of an object or the magnification. Progress checks have been written into this lesson at regular intervals so that students are constantly assessing their understanding.

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.

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 lesson describes sex linkage, focusing on the the inheritance of genes on the X chromosome that lead to haemophilia and Duchenne muscular dystrophy. The PowerPoint and accompanying resources have been designed to cover specification point [e] in topic 3 of A2 unit 4 of the WJEC A-level Biology specification. 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 and they will be challenged to find evidence to support this decision later in the lesson. In terms of humans, the lesson focuses on haemophilia 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 misconceptions

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 point 17.2 (b) of the CIE International 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 18 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 describes the effects of enzyme and substrate concentration on enzyme activity. The PowerPoint and accompanying resources are the third in a series of 3 lessons which cover the details of point 2.1.4 (d) [i] of the OCR A-level Biology A specification and students are also challenged on their recall of the details of transcription and translation as covered in module 2.1.3. The first part of the lesson describes how an increase in substrate concentration will affect the rate of reaction when a fixed concentration of enzyme is used. Time is taken to introduce limiting factors and students will be challenged to identify substrate concentration as the limiting factor before the maximum rate is attained and then they are given discussion time to identify the possible factors after this point. A series of exam-style questions are used throughout the lesson and the mark schemes are displayed to allow the students to assess their understanding and for any misconceptions to be immediately addressed. Moving forwards, the students have to use their knowledge of substrate concentration to construct a graph to represent the relationship between enzyme concentration and rate of reaction and they have to explain the different sections of the graph and identify the limiting factors. The final section of the lesson describes how the availability of enzymes is controlled in living organisms. Students will come to recognise that this availability is the result of enzyme synthesis and enzyme degradation and a SPOT THE ERRORS task is used to challenge their recall of protein synthesis. Please note that this lesson explains the Biology behind the effect of concentration on enzyme activity and not the methodology involved in carrying out such an investigation as this is covered in the lessons designed in line with point 2.1.4 (d) [ii]

This lesson describes how the products of the light-independent reactions of photosynthesis are used by plants, animals and other organisms. The engaging and detailed PowerPoint and accompanying resources have been primarily designed to cover point 5.8 (ii) of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification concerning the uses of GP and GALP but as the lesson makes continual references to biological molecules, it can act as a revision tool for a lot of the content of topic 1 and 2. The previous lesson described the light-independent reactions and this lesson builds on that understanding to demonstrate how the intermediates of the cycle, GP and GALP, are used. The start of the lesson challenges the students to identify two errors in a diagram of the cycle so that they can recall that most of the GALP molecules are used in the regeneration of ribulose bisphosphate. A quiz version of Pointless runs throughout the lesson and this is used to challenge the students to recall a biological molecule from its description. Once each molecule has been revealed, time is taken to go through the details of the formation and synthesis of this molecule from GALP or from GP in the case of fatty and amino acids. The following molecules are considered in detail during this lesson: glucose (and fructose and galactose) sucrose starch and cellulose glycerol and fatty acids amino acids nucleic acids A range of activities are used to challenge their prior knowledge of these molecules and mark schemes are always displayed for the exam-style questions to allow the students to assess their understanding. As detailed above, this lesson has been specifically written to tie in with the earlier lessons in this topic on the structure of the chloroplast and the light-dependent and light-independent reactions of photosynthesis

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 ensures that students know the meaning of key ecological terms and explains how biotic and abiotic factors control the distribution of organisms. The engaging PowerPoint and accompanying resources have been designed to cover points 5.1, 5.2 and 5.3 of the Pearson Edexcel A-level Biology A (Salters Nuffield) specification and therefore cover the biological definitions of ecosystem, community, population and habitat. A quiz round called REVERSE Biology Bingo runs throughout the lesson and challenges students to recognise the following key terms from descriptions called out by the bingo caller: community ecosystem abiotic factor photosynthesis respiratory substrate biomass calorimetry distribution niche The ultimate aim of this quiz format is to support the students to understand that any sugars produced by photosynthesis that are not used as respiratory substrates are used to form biological molecules that form the biomass of a plant and that this can be estimated using calorimetry. Links are made to photosynthesis and net primary productivity as these will be met later in topic 5 as well as challenging their prior knowledge of adaptations, classification and biological molecules. The final part of the lesson uses an exam-style question to get the students to recognise that biotic and abiotic factors control the distribution of organisms in a habitat and to recall the concept of niche.

This lesson outlines how bacteria become resistant to antiobiotics and discusses its consequences and the steps taken to reduce its impact. The PowerPoint and accompanying worksheet have been designed to cover specification points 10.2 (b & c) of the CIE A-level Biology specification President Trump’s error ridden speech about antibiotics is used at the beginning of the lesson to remind students that this is a treatment for bacterial infections and not viruses as he stated. Moving forwards, 2 quick quiz competitions are used to introduce MRSA and then to get the students to recognise that they can use this abbreviation to remind them to use mutation, reproduce, selection (and survive) and allele in their descriptions of the development of resistance by evolution through natural selection. The main task of the lesson challenges the students to form a description to explain how this strain of bacteria developed resistance to methicillin, making use of the five key terms emphasised above. Moving forwards, there is a focus on the hospital as the common location for MRSA infections and students will recognise that this opportunistic pathogen can infect through open wounds to cause sepsis and potentially death. Figures from infections and deaths in hospitals in the US are used to increase the relevance and students will learn how a MRSA prevention program in VHA facilities includes screening of surgery patients to try to reduce its impact. The lesson concludes with a discussion about other methods that can be used by hospitals and general practitioners to reduce the impact of MRSA and to try to prevent the development of resistance in other strains.

This lesson explains how a nerve impulse (action potential) is conducted along an axon and focuses on the role of the sodium and potassium ions. The PowerPoint and accompanying resources have been designed to cover point 8.4 of the Edexcel International A-level Biology specification and contains detailed descriptions of resting potential, depolarisation, repolarisation, hyperpolarisation and the refractory period. This topic is commonly assessed in the terminal exams so extensive planning ensures that this resource includes a wide range of activities to motivate and engage the students whilst ensuring that the content is covered in the depth of detail that will allow them to have a real understanding. Interspersed within the activities are understanding checks and prior knowledge checks to enable the students to not only assess their progress against the current topic but also to challenge themselves on the links to earlier topics such as methods of movements across cell membranes. There are also a number of quiz competitions which are used to introduce key terms and values in a fun and memorable way and discussion points to encourage the students to consider why a particular process or mechanism occurs. Over the course of the lesson, the students will learn and discover how the movement of ions across the membrane causes the membrane potential to change. They will see how the resting potential is maintained through the use of the sodium/potassium pump and potassium ion leakage. There is a real focus on depolarisation to allow students to understand how generator potentials can combine and if the resulting depolarisation then exceeds the threshold potential, a full depolarisation will occur. At this point in the lesson students will discover how the all or nothing response explains that action potentials have the same magnitude and that instead a stronger stimulus is linked to an increase in the frequency of the transmission. The rest of the lesson challenges the students to apply their knowledge to explain how repolarisation and hyperpolarisation result and to suggest advantages of the refractory period for nerve cells.

This engaging lesson describes the relationship between the structure, properties and functions of a phopholipid and cholesterol. The PowerPoint has been written as the second lesson in a series of two that cover specification points 2.1.2 (h), (i) & (j) of the OCR A-level Biology A course and there is a particular focus on their roles in membranes to link to module 2.1.5. In the previous lesson, the students met triglycerides and a quick quiz round called FAMILY AFFAIR is used at the start of the lesson to challenge the students on their knowledge of the structure of this macromolecule to identify the shared features in a phospholipid. This then allows the differences to be introduced, such as the presence of a phosphate group in place of the third fatty acid. Moving forwards, the students will learn that the two fatty acid tails are hydrophobic whilst the phosphate head is hydrophilic which leads into a key discussion point where the class has to consider how it is possible for the phospholipids to be arranged when both the inside and outside of a cell is an aqueous solution. The outcome of the discussion is the introduction of the bilayer which is critical for the lesson in module 2.1.5 on the fluid mosaic model. Students are briefly introduced to facilitated diffusion and reminded of active transport so they can recognise that proteins will be found in the membrane to allow for movement of large or polar molecules. The remainder of the lesson focuses on cholesterol, beginning with the structure. The hydrophobic nature of this molecule is then considered and discussed so that they can understand its role in the regulation of membrane fluidity. That just leaves one final quiz round which identifies vitamin D, testosterone and oestrogen as three substances that are formed from cholesterol

This detailed lesson describes the different levels of protein structure and focuses on the bonds that hold these molecules in shape. Both the engaging PowerPoint and accompanying resources have been designed to cover specification point 2.3 (b) of the CIE International A-level Biology course and makes continual links to previous lessons such as amino acids & peptide bonds as well as to upcoming lessons like enzymes and antibodies. The start of the lesson focuses on the formation of a peptide bond during a condensation reaction so that students can understand how a dipeptide is formed and therefore how a polypeptide forms when multiple reactions occur. The main part of the lesson describes the different levels of protein structure. A step by step guide is used to demonstrate how the sequences of bases in a gene acts as a template to form a sequence of codons on a mRNA strand and how this is translated into a particular sequence of amino acids known as the primary structure. The students are then challenged to apply their understanding of this process by using three more gene sequences to work out three primary structures and recognise how different genes lead to different sequences. Moving forwards, students will learn how the order of amino acids in the primary structure determines the shape of the protein molecule, through its secondary, tertiary and quaternary structure and time is taken to consider the details of each of these. There is a particular focus on the different bonds that hold the 3D shape firmly in place and a quick quiz round then introduces the importance of this shape as exemplified by enzymes, antibodies and hormones. Students will see the differences between globular and fibrous protein and again biological examples are used to increase relevance. The lesson concludes with one final quiz round called STRUC by NUMBERS where the students have to use their understanding of the protein structures to calculate a numerical answer.

This detailed lesson describes the key structural features of a prokaryotic cell and compares these against the structures of an eukaryotic cell. The engaging PowerPoint and accompanying resources have been designed to cover specification points 1.2 (d) & (e) as detailed in the CIE International A-level Biology specification and describes how the size and cell structures differ as well as the additional features that are found in some prokaryotic cells and briefly introduces binary fission. A clear understanding of terminology is important for A-level Biology so this lesson begins with a challenge, where the students have to recognise a prefix that they believe translates as before or in front of . This leads into the discovery of the meaning of prokaryote as before nucleus and this acts to remind students that these types of cell lack this cell structure. Links to the previous lessons on the eukaryotic cells are made throughout the lesson and at this particular point, the students are asked to work out why the DNA would be described as naked and to state where it will be found in the cell. Moving forwards, the students will discover that these cells also lack membrane bound organelles and a quick quiz competition challenges them to identify the specific structure that is absent from just a single word. In addition to the naked DNA, students will learn that there are also ribosomes in the cytoplasm and will discover that these are smaller than those found in the cytoplasm of an eukaryotic cell (but the same size as those in chloroplasts and mitochondria). The remainder of the lesson focuses on the composition of the cell wall, the additional features of prokaryotic cells such as plasmids and there is also the introduction of binary fission as the mechanism by which these organisms reproduce

This fully-resourced lesson compares the structure and ultrastructure of a prokaryotic cell against an eukaryotic cell. The engaging PowerPoint and accompanying resources have been designed to cover specification point 2.1.1 (k) as detailed in the OCR A-level Biology A specification and describes how the size and cell structures differ as well as the additional features that are found in some prokaryotic cells and briefly introduces binary fission. A clear understanding of terminology is important for A-level Biology so this lesson begins with a challenge, where the students have to come up with a 3-letter prefix that they believe will translate as before or in front of . This leads into the discovery of the meaning of prokaryote as before nucleus which acts to remind students that these types of cell lack this cell structure. Links to the previous lessons on the eukaryotic cells are made throughout the lesson and at this particular point, the students are asked to work out why the DNA would be described as naked and to state where it will be found in the cell. Moving forwards, the students will discover that these cells also lack membrane bound organelles and a quick quiz competition challenges them to identify the specific structure that is absent from just a single word. In addition to the naked DNA, students will learn that there are also ribosomes in the cytoplasm and will discover that these are smaller than those found in the cytoplasm of an eukaryotic cell (but the same size as those in chloroplasts and mitochondria). The remainder of the lesson focuses on the composition of the cell wall, the additional features of prokaryotic cells such as plasmids and there is also the introduction of binary fission as the mechanism by which these organisms reproduce so that students can recognise that these cells do not contain centrioles

This detailed lesson describes how changes in ventilation rate are brought about to allow for the delivery of oxygen and the removal of carbon dioxide. The engaging PowerPoint and accompanying resources have been designed to cover the second part of point 7.9 (ii) in the Pearson Edexcel A-level Biology A specification. The previous lesson described the control of heart rate so this lesson has been written to tie in with this and to use this knowledge to further the students understanding of the control of ventilation rate. The lesson begins with a focus on the muscles involved in ventilation, specifically the diaphragm and external intercostal muscles, so that students can understand how their contraction results in an increase in the volume of the thoracic cavity. Boyle’s law is briefly introduced to allow students to recognise the relationship between volume and pressure so that the movement of air with the pressure gradient can be described. Time is then taken to consider the importance of inhalation and an exam-style question challenges the students to explain that a constant supply of oxygen to the alveoli is needed to maintain a steep concentration gradient with the surrounding capillaries. The students are then tasked with writing a description of exhalation at rest using the description of inhalation as their guide. The rest of the lesson focuses on the mechanisms involved in increasing the rate and depth of breathing during exercise. Students will use their knowledge of the control of heart rate to recall that chemoreceptors detect changes in oxygen and carbon dioxide and blood pH and that the medulla oblongata processes the sensory information that it receives before coordinating a response. The final task challenges them to use the information provided in this lesson and the previous one to order 10 detailed descriptions so they can form a complete passage about this control system.