Interactive Self-Study A-Level Biology Course

Course Progress

Course Navigation

  • Biochemistry & molecular biology
    • Biological polymers & their monomers
    • Carbohydrates
    • Lipids
    • Proteins
    • Enzymes
    • Nucleic acids
    • DNA replication
    • ATP
    • Water
    • Inorganic ions
    • Exam Questions & Revision
  • Cells
    • An introduction to eukaryotic cell structure
    • Eukarya – animal & plant cell structure
    • Eukarya – animal & plant tissues & organs
    • Structure of prokaryotic cells & viruses
    • Optical & electron microscopy
    • Cell fractionation & ultracentrifugation
    • Mitosis & the cell cycle
    • Membranes & transport
    • Immunology
    • Monoclonal antibodies
    • Further Virology
    • Exam Questions & Revision
  • Exchange & transport systems
    • Introduction, protoctista & insects
    • Fish & amphibians
    • Dicotyledonous leaves
    • Lungs
    • The structure & function of haemoglobin
    • Adaptations of different organisms haemoglobin
    • Circulation & exchange
    • Heart & cardiac cycle
    • Cardiovascular disease
    • Structure & Function of the Digestive System
    • Digestion of carbohydrates, proteins & lipids
    • Absorption of digestive products
    • Cholera
    • Phloem structure & function, sucrose sources & sinks
    • Translocation – experimental evidence & theories
    • Xylem structure & function
    • Transpiration – experimental evidence & theories
    • Exam Questions & Revision
  • Genetics, variation & biodiversity
    • The genetic code – introns & exons
    • Transcription & translation
    • Gene mutations
    • Meiosis
    • An introduction to natural selection
    • Types of natural selection
    • Species, classification & taxonomy
    • Biochemical & genetic evidence used in classification
    • Courtship behaviour
    • Biodiversity – species diversity index
    • Biodiversity & farming
    • Exam Questions & Revision
  • Energy in Biological Systems
    • Autotrophs & heterotrophs
    • Photosynthesis – biochemistry
    • Photosynthesis – experimental evidence
    • Respiration – glycolysis
    • Respiration – forms of anaerobic respiration
    • Aerobic respiration, Krebs cycle & ETC
    • Energy flow – ecosystems
    • Energy flow – farming & fertilisers
    • The nitrogen & phosphorus cycles
    • Exam Questions & Revision
  • Sensitivity, coordination & control systems
    • Taxes, kineses & reflexes
    • Receptors – the Pacinian corpuscle & the eye
    • Chemical control in plants
    • Control of the heart rate
    • Neurones & impulses
    • Synaptic transmission
    • Human Nervous System & Brain 
    • Muscle physiology
    • Homeostasis & Hormones: Control of blood glucose
    • Hormones & osmoregulation
    • Exam Questions & Revision
  • Genetics, evolution & ecology
    • Introduction & monohybrid inheritance
    • Dihybrid inheritance
    • Gender & sex linkage
    • Incomplete dominance, codominance & multiple alleles
    • Polygenic inheritance, epistasis & lethal genes
    • The chi squared test
    • Population genetics – Hardy Weinberg
    • Speciation & evolution
    • Types of natural selection
    • Introduction to ecology
    • Ecological techniques
    • Rocky shore fieldwork
    • Succession
    • Exam Questions & Revision
  • The control of gene expression
    • Gene & chromosomal mutations
    • Cell potency & differentiation
    • Regulation of transcription & translation – 1
    • Regulation of transcription & translation – 2 (epigenetics)
    • Introduction to Cancer
    • Genes & cancer
    • Using genome projects
    • Genetic engineering – vectors, plasmids, transgenics 
    • Genetic engineering – locating & isolating genes
    • Gene therapy
    • DNA probes
    • Genetic fingerprinting
    • Exam Questions & Revision
  • Practical & Investigative Skills
    • Overview of Practical Skills
    • Opinions & Evidence
    • Hypothesis & Prediction
    • Types of Variable
    • Conducting Fair Tests
    • Accuracy, Precision & Sensitivity
    • Selecting & Using Apparatus
    • Reliability, Validity & Error
    • Presenting Data in Tables
    • Principles of Graph Drawing
    • Non-Linear Graphs
    • Linear Graphs
    • Interpreting Data & Drawing Conclusions
    • Recognising Mathematical Relationships
    • Biological Drawings
    • Science, Society & Ethics
  • Statistics in Biology
    • Introduction to Statistical Tests
    • Central Tendency & Normal Distribution
    • Dispersion & Standard Deviation
    • Student’s t-test for paired samples
    • Student’s t-test for independent samples
    • Pearson’s PMC Coefficient
    • Spearman Rank Correlation Coefficient
  • Exam Technique: Core Skills
    • Exam Question Styles
    • Command Words
    • Common Errors
    • Practical-Based Exam Questions
    • Synoptic Essays

Below is a list of the individual lessons within each topic of this A-level biology course, with an outline of what each lesson covers.

Click on a lesson to get started, or click the ‘course navigation’ button above.

Biochemistry & Molecular Biology

An introduction to the structures of biological macromolecules and polymers, with an overview of the main types of such molecules found in biological systems, condensation reactions and hydrolysis reactions.

Structure of carbohydrates (monosaccharides, disaccharides & polysaccharides), including glycosidic bonding & their functional categorisation (structural vs. storage), with examples from different organisms.

Structure of monoglycerides, diglycerides & triglycerides, including the variation of physical properties of lipids with their structure and bonding and an overview of their formation through condensation reactions.

The significance of proteins in biology, and a detailed explanation of their structure in terms of their monomers (amino acids), primary, secondary, tertiary and quaternary structures and how these relate to their functions.

Characteristics of enzymes, and how their properties are determined by their structure; “lock & key” hypothesis and the induced fit model of enzyme action; factors affecting the rate of enzyme-catalysed reactions.

Structure of nucleotides and polynucleotides (DNA & RNA); bonding in polynucleotides, including Chargaff’s rules of base-pairing by H-bonding and the phosphodiester bond; 3 main types of RNA (mRNA, rRNA, tRNA).

The need for DNA replication, and the development of competing models to explain the process by which DNA replicates; Meselson-Stahl experiment; Semi-conservative mechanism of DNA replication.

Structure of adenosine triphosphate (ATP) and its function as the “energy currency” of the cell; the release of energy from ATP by hydrolysis, and the storage of energy in the formation of ATP by condensation reaction.

The importance of water due to its many essential functions in biology; the molecular structure, bonding and physical and chemical properties of water, and the roles of these properties in biological systems & processes.

An overview of the functions and sources of many inorganic ions required by plants and animals, as well as important related concepts such as deficiency & pH; includes phosphate, nitrate, potassium, iron & sodium ions.

In this lesson we review a number of exam questions on various aspects of this topic, discuss students’ answers to the questions and the examiners’ marking and comments, highlighting key aspects of exam technique.

Cell Biology

The 3-domain classification system; comparative sizes of different cells; details of eukaryotic cell structure (vs. prokaryotes), including chromosomes, mitochondria, chloroplasts, ribosomes; examples from Euk. kingdoms.

Further details of Euk. cell structure, exemplified by plant & animal cells; including structure & function of lysosomes, centrioles, cell walls (incl. algal & fungal) & other organelles; differences between plant & animal cells.

Structures & functions of animal & plant tissues, epithelium, connective, skeletal, blood, muscle & nervous (animal) tissues; photosynthetic, epidermal, vascular, meristem, packing & strengthening (plant) tissues.

Structure of prokaryotic cells (bacteria & archaea); examples of archaea, and categorisation of bacterial types by morphology; categorisation of viruses by genetic material (DNA & RNA), structure & life-cycles of viruses.

Key terms and concepts in microscopy, including graticules, staining, magnification & resolution; the functional parts of optical (including confocal & fluorescence) and electron (scanning and transmission) microscopes.

The stages of the procedure of cell fractionation, including the preparation of samples; the stages in the process of ultracentrifugation, including the procedures of differential and density-gradient ultracentrifugation.

Significance of mitosis; the process of mitosis and the sequence of events in each phase (prophase, metaphase, anaphase, telophase & cytokinesis); the stages of the cell cycle and the events which occur at each stage.

Fluid mosaic model; membrane permeability to different types of particle; membrane transport mechanisms (simple/facilitated diffusion, osmosis, active transport, endocytosis & exocytosis); surface area to volume ratio.

A detailed explanation of non-specific immunity (physical/chemical barriers & phagocytosis) and specific immunity (production of antibodies & the cell-mediated response), including immunological memory.

An extension of the ideas from the last lesson; Antigens & antibodies; B-lymphocytes, clonal selection & clonal expansion; medical (diagnostic & therapeutic) applications of the production of monoclonal antibodies.

Examples of pathogenic viruses to illustrate and expand upon ideas about viruses covered in previous lessons of this topic; includes chickenpox, antigenic variability (antigenic shift & drift) & vaccination for influenza.

In this lesson we review a number of exam questions on various aspects of this topic, discuss students’ answers to the questions and the examiners’ marking and comments, highlighting key aspects of exam technique.

Exchange & Transport Systems

Introduction to gas exchange, with basic principles illustrated through an overview of gas exchange systems in unicellular organisms (protoctistans) and insects; Fick’s law & the factors which determine rate of diffusion.

Structure & function of gills in fish; ventilation in fish; counter-current exchange system (vs. parallel flow); structural factors affecting the efficiency of gas exchange; gas exchange in amphibians (tadpole & adult frog).

Structural adaptations of dicotyledonous leaves for efficient gas exchange; gas exchange in leaves during hours of daylight vs. darkness; factors affecting efficiency of gas exchange; adaptations of xerophytic plants.

Structure & function of the lungs, including the anatomy of the thorax, mechanism of ventilation at rest vs. during exercise & pressure changes in lungs & pleura; factors affecting efficiency of gas exchange in lungs.

The structure and function of haemoglobin; cooperative binding (allostery) of oxygen to haemoglobin; oxygen dissociation curves; the “Bohr shift”; different forms of haemoglobin and their oxygen dissociation curves.

More teaching about the adaptations of haemoglobin in different organisms (mentioned in the previous lesson) given the different oxygen partial pressures of their habitats.

Structure & function of the mammalian circulatory system; pulmonary vs. systemic circulation; relevance of surface area vs. volume ratio; capillaries & metabolic exchange; formation of tissue fluid & the lymphatic system.

Structure of the heart; morphology of cardiac muscle cells; heart valves; cardiac cycle, including pressure changes during atrial & ventricular systole & diastole; heart rate, stroke volume & cardiac output at rest vs. exercise.

Prevalence & risk factors of cardiovascular disease; pathology of coronary heart disease, including atherosclerosis, myocardial infarction & aortic aneurysm; effects of excess cholesterol; blood pressure & hypertension.

Structure & function of the human digestive system, to include both the major organs and accessory structures; mechanism of peristalsis; overview of digestive enzymes secreted in different parts of the digestive system.

Detailed description & explanation of the chemical digestion of carbohydrates, proteins and lipids by digestive enzymes in various parts of the alimentary canal (extending the overview given in the previous lesson).

Structure of the mammalian gut with reference to the absorption of digestive products, including structure of villi and the mechanisms of transport of monosaccharides, amino acids, fatty acids & glycerol across gut lining.

A lesson in which we examine the pathology of cholera to apply the concepts covered in previous lessons concerning the absorption of digestive products to explaining the symptoms of this disease in infected persons.

Structure of phloem (sieve tubes & companion cells); positive phloem sap pressure; distribution of phloem in different plants; sucrose sources & sinks; seasonal variation in sources & sinks.

Experiments, their data & models of the movement of assimilates through the phloem arising from them which have led to our modern understanding of translocation in the phloem.

Structure of xylem tissue; development & maturation of xylem vessels; apoplastic & symplastic pathways in root; models for the mechanism of transport in xylem (capillarity, root pressure & cohesion-tension theory).

Experiments, their data & models of the water movement in the xylem arising from them which have led to our modern understanding of the water transport mechanism in xylem tissue.

In this lesson we review a number of exam questions on various aspects of this topic, discuss students’ answers to the questions and the examiners’ marking and comments, highlighting key aspects of exam technique.

Genetics, Variation & Biodiversity

DNA in prokaryotes vs. eukaryotes (including mitochondrial & chloroplast DNA); the “central dogma” of molecular biology; introns & exons; post transcriptional modification of mRNA; the features of the genetic code.

Overview of protein synthesis; euk. & prok. ribosomes; detailed description of the processes of transcription (including post-transcriptional modification of mRNA) and translation (initiation, elongation & termination).

Role of mutation in evolution; causes of mutations; examples of gene (point) mutations and their effects, including substitutions, deletions & additions, with examples of effects on phenotype (albinism & retinoblastoma).

Significance of meiosis; the process of meiosis, and the sequence of events in each stage of meiosis (prophase, metaphase, anaphase, and telophase in the first and second meiotic divisions); non-disjunction & mutation.

Changes in allele frequency & evolution; genetic drift; genetic bottlenecks & extinction; the founder effect; Darwin’s theory of “survival of the fittest”; mechanism of natural selection with examples (rat warfarin resistance).

The first of two lessons on types of natural selection in this course (the second can be found in the topic “genetics, evolution & ecology”); stabilising & directional selection; antibiotic resistance & MRSA, tuberculosis.

Origin of the modern method of classification; the concept of a species; 5 kingdom & 3 domain classification systems; taxonomy and classification (including “form” & “phylogenetic” classification) with many examples.

Traditional classification methods (comparing anatomy, embryology & behaviour) vs. modern approaches (sequencing DNA or amino acids in proteins, immunological studies).

Reproductive behaviours in animals (random external, protected & internal fertilisation); relationships between mates (monogamy, polygamy & promiscuity); examples of courtship behaviour & its role in many animals.

Measuring species diversity; calculation of Simpson’s Diversity Index; importance & methods of random sampling; interpretation of Simpson’s Diversity Index; sampling techniques; examples of applications in fieldwork.

Components of biodiversity (ecosystem, genetic & species diversity); implications of intensive farming practices for biodiversity, including use of herbicides & pesticides, monoculture, ploughing, sowing, harvesting, etc.

In this lesson we review a number of exam questions on various aspects of this topic, discuss students’ answers to the questions and the examiners’ marking and comments, highlighting key aspects of exam technique.

Energy in Biological Systems

Distinction between heterotrophs & autotrophs; photoautotrophs & chemoautotrophs; extremophiles and the process of chemosynthesis; overview of photosynthesis; structural adaptations of photoautotrophs.

Photosynthetic pigments & their organisation in thylakoid membranes (antenna complexes); detailed description & explanation of the light-dependent & light independent reactions of photosynthesis; limiting factors.

Experiments supporting our current understanding of the biochemical pathways involved in photosynthesis, including those of Ruben & Kamen, Blackman, Engelmann & Calvin et al; measuring rate of photosynthesis.

Significance of glycolysis; role of ATP; the sequence of biochemical reactions involved in glycolysis, including phosphorylation & isomerisation of glucose, cleavage of fructose-1,6-bisphosphate & formation of pyruvate.

Significance of anaerobic respiration; anaerobic pathways in plants, animals and fungi, including the biochemical reactions which produce lactic acid and ethanol; anaerobic respiration in muscle cells & the “oxygen debt”.

Phases of aerobic respiration; biochemical reactions involved in the “link reaction” & Krebs Cycle (including respiratory substrates other than glucose) & the elctron transport chain; chemiosmotic theory of ATP synthesis.

Key concepts in ecological bioenergetics; biomass and energy losses at each trophic level in a food chain; pyramids of numbers, biomass & energy; calorimetry; ecological efficiency. net primary & secondary production.

Intensive farming practices (hydroponics, glasshouses, fish farms, battery farming), their advantages & disadvantages, and importance of reducing energy losses; need for & use of fertilisers (organic vs. inorganic).

4 main processes of the nitrogen cycle (nitrogen fixation, ammonification, nitrification & denitrification); roles of mycorrhizae & mycorrhizal associations; impact of nitrogen fertilisers (eutrophication); the phosphorus cycle.

In this lesson we review a number of exam questions on various aspects of this topic, discuss students’ answers to the questions and the examiners’ marking and comments, highlighting key aspects of exam technique.

Sensitivity, Coordination & Control Systems

Adaptive value of phototaxis & chemotaxis, orthokinesis & klinokinesis; reflex actions and the reflex arc; modulation of reflexes; examples including pupillary, knee-jerk, withdrawal, cough, shivering & blink reflexes.

Classification of receptors (exteroceptors, enteroceptors, proprioceptors); structure & function of Pacinian corpuscles and rod & cone cells of the retina (including signal transduction & production of generator potentials).

Plant growth factors (auxins, giberellins, ethane, florigens); phototropism, hydrotropism, gravitropism & thigmatropism; experimental demonstration of tropisms, and role of plant growth factors in plant growth responses.

Origin of heartbeat; conduction system of the heart (sino-atrial & atrio-ventricular nodes, bundle of His & Purkinje fibres; ECG; electrical properties of cardiac muscle; sympathetic & parasympathetic control of heart rate.

Structure of sensory, motor & relay neurones; maintenance of resting membrane potential & generation of the action potential; role of sodium & potassium ion channels (voltage-gated & leak) and Na/K-ATPase pump.

Structure of synapses & neuromuscular junctions; unidirectionality, summation & inhibition of synaptic transmission; sequence of events at synapse following arrival of action potential resulting in signal transmission.

In this lesson we review the structure and function of the human nervous system, including a detailed review of the human brain; we also cover non-invasive methods through which we can study the brain.

Skeletal muscle structure ; muscle fibre structure & types, myofilaments & banding pattern; contractile proteins & sliding filament mechanism; length-tension relationship; excitation-contraction coupling; energy sources.

Homeostasis & negative feedback; structure & function of endocrine system; hormonal control of blood glucose concentration; diabetes mellitus; glucose tolerance tests.

Nervous vs. hormonal coordination; endocrine organs & their secretions/functions; structure of the kidney & nephrons; glomerular filtration, selective tubular reabsorption, counter-current multiplier; control by ADH.

In this lesson we review a number of exam questions on various aspects of this topic, discuss students’ answers to the questions and the examiners’ marking and comments, highlighting key aspects of exam technique.

Genetics, Evolution & Ecology

Mendel’s experiments & conclusions leading to his Laws of Segregation & Independent Assortment; monohybrid crosses & determination of F1 and F2 genotypic & phenotypic ratios, with examples.

Mendel’s work in dihybrid inheritance; Law of Independent Assortment; independent assortment in meiosis; determination of expected genotypic & phenotypic ratios for dihybrid crosses, with examples; test crosses.

Genetic determination of gender in humans & other animals; sex chromosomes; autosomal linkage and modified (non-Mendelian) genetic ratios; sex linkage in humans (e.g. haemophilia & colour blindness).

Distinction between incomplete dominance & codominance; examples of incomplete dominance and codominance with two alleles or multiple alleles leading to non-Mendelian ratios.

Interactions of genes in determining a characteristic (polygenic inheritance); Epistasis & lethal alleles; examples to illustrate the genotypic & phenotypic ratios in offspring due to these mechanisms of inheritance.

Determining statistical significance of differences between expected vs. observed genotypic & phenotypic ratios (e.g. from Mendelian monohybrid & dihybrid crosses) using the chi-squared test, with examples.

Key concepts & terminology in population genetics; the gene pool; allele frequencies; the Hardy-Weinberg equation and its use in calculating allele frequencies, with examples; Hardy-Weinberg equilibrium conditions.

Definition of a species & its limitations; isolating mechanisms (including geographical & reproductive); allopatric & sympatric mechanisms of speciation; examples of isolation & speciation mechanisms; Darwin’s finches.

The mechanisms by which disruptive, diversifying and directional selection alter the distributions of phenotypes in populations and can lead to speciation, illustrated with many examples in humans and other populations.

Scope of ecology; key terms and concepts in ecology; biomes & ecosystems; abiotic conditions in major biomes and the adaptations of organisms found in each biome; ecological niches; predator-prey relationships.

Practical methods used by ecologists for investigating the biotic and abiotic components of ecosystems; examples include the Tullgren funnel, Pooter, kick-sampling, frame & point quadrats, belt transects.

Examples of fieldwork conducted by ecologists on rocky shores to illustrate some of the ecological techniques and concepts covered in previous lessons of this course; includes zonation studies using belt transects.

Stages in ecological succession; stages & features of primary & secondary succession, illustrated with examples of primary succession on bare rock, sand dunes, ponds & lakes and secondary succession after forest fires.

In this lesson we review a number of exam questions on various aspects of this topic, discuss students’ answers to the questions and the examiners’ marking and comments, highlighting key aspects of exam technique.

The Control of Gene Expression

Mutation in evolution; gene (point) vs. chromosomal mutations; examples of point mutations (substitution, deletion & addition) and chromosomal mutations (deletion, duplication, inversion; insertion vs. translocation).

Significance & process of differentiation (including in plants); concept of cell potency (totipotency, pluripotency, multipotency & unipotency); embryonic & adult stem cells; sources & potential medical uses of stem cells.

Description & explanation of different types of mechanisms for regulation of gene expression (transcriptional, post-transcriptional, translational & post-translational); activators & repressors; RNA interference; examples.

Nucleosome structure; methylation of DNA & histones; protein acetylation & deacetylation; epigenetic control of differentiation; histone acetylation, DNA methylation & cancer.

Categorisation of tumours (benign vs. malignant) & their features; types of cancer; metastasis; incidence of cancer; risk factors; pathology of lung cancer & malignant melanoma; breast & cervical cancer.

Proto-oncogenes and tumour-suppressor genes, and their role in regulation of cell cycle and mitosis; consequences of mutations in proto-oncogenes & tumour suppressor genes, with examples of cancer caused by these.

Genome & epigenome; genomics vs. proteomics; genetic diversity & DNA; milestones in the development of genomics; Human Genome Project; nanopore technology; next-generation sequencing technologies.

Recombinant DNA technology procedure, including restriction enzymes, vectors, ligase, ultracentrifugation; examples of production of transgenic plants & animals.

The use of automated artificial gene synthesis, shotgunning & reverse transcription to locate and isolate specific genes in genetic engineering, with examples.

Gene therapy and its potential applications; somatic & germ-line therapies; vectors for gene therapy (virus & liposome-mediated gene therapies); cystic fibrosis & potential treatment by gene therapy.

Use of DNA probes for diagnosis, including DNA isolation/extraction, DNA fragmentation, separation of fragments by electrophoresis, location of specific sequences using the DNA probe & the analysis of results.

The potential applications & process of genetic fingerprinting including electrophoresis, southern blotting, hybridisation, autoradiography & interpreting results; applications in palaeoanthropology; PCR technique.

In this lesson we review a number of exam questions on various aspects of this topic, discuss students’ answers to the questions and the examiners’ marking and comments, highlighting key aspects of exam technique.

Practical & Investigative Skills

In this introductory lesson, we introduce the main stages involved in practical investigations, and review the key aspects of each; these will each be covered in-depth in subsequent lessons of this topic.

In this lesson we’ll address the distinction between opinion and evidence, and the importance of the testability, reliability and validity of evidence in formulating and supporting scientific opinion.

In this lesson we highlight and explain the importance of the hypothesis in the overall scientific method, distinguishing between hypothesis & prediction, and between positive and negative (null) hypothesis.

In this lesson, we explain the importance of the independent, dependent & control variables for an investigation, and categorise these variables as being discrete, ordered, categoric or continuous.

In this lesson, we review the importance of pilot testing and control variables in ensuring that testing is fair in scientific investigations, and the key aspects of testing procedures required for fair testing.

In this lesson we define and distinguish between the terms “accuracy”, “precision” & “sensitivity”, explaining the importance of each of these in scientific investigations and how to maximise them.

In this lesson we’ll review the key points to consider when selecting, calibrating and using the appropriate apparatus to perform a scientific investigation to maximise accuracy, precision & sensitivity.

In this lesson we cover the concepts of reliability, reproducibility, validity and the sources & types of error in scientific investigations, together with methods to improve investigations in these respects.

In this lesson we cover the importance of presenting experimental data in tables, and the key aspects of constructing tables for presenting primary data from investigations through a number of examples.

In this lesson we identify and explain the general principles through which data can be presented appropriately in graphs &charts, outlining how these principles are applied with a number of examples.

In this lesson we explain how data can be presented in various non-linear graphs and charts, including: pie & bar charts, frequency diagrams & polygons, histograms, kite & rose diagrams, and stem & leaf diagrams.

In this lesson we cover the use of various types of linear graphs to represent experimental data (including line & scatter graphs, frequency polygons and logarithmic graphs) and the use of error & range bars.

In this lesson we cover the techniques required to analyse &interpret experimental data to arrive at valid conclusions, including identifying when links between variables are causal, by association or by chance.

In this lesson we cover the various types of mathematical relationships between variables in experimental data, including direct & inverse proportion, and exponential, sigmoid & oscillatory relationships.

In this lesson we describe the protocol for drawing biological specimens, and evaluate a number of examples of students’ biological drawings to understand the proper approach and common errors to avoid.

In this lesson we discuss the role & value of science in society, the importance of bias and the limitations of science, and the ethical, societal and environmental implications of scientific research and applications.

Statistics in Biology

In this lesson we introduce the fundamental concepts of probability and hypothesis testing in statistics, and review three useful statistical tests: Wilcoxon matched pairs, Pearson PMC and Mann-Whitney U tests.

In this lesson we cover the statistical concepts of measures of central tendency and normal distribution, applying these concepts to the measurement of biological variation through a number of worked examples.

In this lesson we review statistical measures of dispersion, inclduing standard deviation, applying these concepts to analysis of data from investigations, and explaining the concept of the standard error of the mean.

In this lesson we describe and explain the Student’s t-Test for paired samples, showing how it can be applied to the statistical analysis of data from a practical investigation involving kinesis in woodlice.

In this lesson we describe and explain the Student’s t-Test for independent samples, showing how it can be applied to the statistical analysis of data from an ecological study of variation in dogwhelks from a rocky shore.

In this lesson we describe and explain the use of Pearson’s product moment correlation coefficient in analysing statistical data, illustrated by the analysis of data from an ecological study of variation in dog whelks.

In this lesson we describe and explain the use of Spearman’s rank correlation coefficient for the analysis of statistical data, illustrating this with its use in analysing data from an ecological study of a rocky shore.

Exam Technique: Core Skills

In this introductory lesson, we describe the different styles of questions you may encounter in an exam, what type of knowledge or skills each style tests, and the optimal approach to revising for and answering each.

In this lesson we describe the meaning of the command (key) words used by examiners, and show the optimal approach to revising for and answering questions containing each command word with a number of examples.

In this lesson we review the most common errors students make in answering exam questions, discuss the reasons students make these errors, and outline the best study & revision practises to avoid making such errors.

In this lesson we review numerous examples of real exam questions testing understanding and recall of practical and investigative procedures, together with real student answers and examiners’ comments and feedback.

In this lesson, we discuss the optimal way to revise for and answer synoptic essay exam questions, including how to produce an effective essay plan, and the marking criteria examiners use for these types of questions.