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Biology - Shared foundations

Topic 1 - Key concepts in biology

Biology 1.1 - Cell structuresLearn how the structures of animal, plant and bacterial cells make their jobs possible, and use those functions to explain similarities and differences between cells.

Biology 1.2 - Specialised cellsConnect the features of sperm, egg and ciliated epithelial cells to their jobs in fertilisation, early development and clearing the airways.

Biology 1.3 - 1.5 - Microscopy and cell scaleFind out how improved resolution reveals cell structures, estimate sizes and convert between cell-scale units. The final part teaches Higher-tier standard-form calculations.

Biology 1.6 - Observing cellsPrepare and observe onion and cheek-cell slides, calculate magnification and cell size, and record evidence in labelled scientific drawings. Evaluate the preparation and sampling choices that affect your observations.

Biology 1.7 - 1.9, 1.12 - How enzymes workExplain enzyme specificity, denaturation and the effects of temperature, pH and substrate concentration. Connect enzyme action to the building and breakdown of biological molecules.

Biology 1.10 - 1.11 - Investigating enzyme activityInvestigate how pH affects amylase, turn the disappearance of starch into an endpoint time, and calculate rates. Use controls and repeated measurements to make the comparison meaningful.

Biology 1.15 - Cell transportDistinguish diffusion, osmosis and active transport, then use concentration gradients to predict net movement into or out of a cell.

Biology 1.16 - 1.17 - Investigating osmosisInvestigate osmosis using potato tissue and sucrose solutions. Calculate percentage gains and losses in mass, interpret the zero-change concentration and improve the quality of your evidence.

Biology 1

Topic 2 - Cells and control

Biology 2.1 - 2.4 - Mitosis, growth and cancerFollow how a cell copies and shares its chromosomes to make two matching daughter cells, then connect this process to growth, repair, asexual reproduction and cancer.

Biology 2.5 - 2.6 - Growth and differentiationDistinguish the processes that make organisms grow and develop working tissues: division supplies cells, elongation lengthens plant cells, and differentiation makes cells suited to particular jobs.

Biology 2.7 - Growth chartsUse percentile charts to monitor growth over time, translate between tables and graphs, and calculate percentage mass gain or loss without confusing it with percentile rank.

Biology 2.8 - 2.9 - Stem cells in medicineExplain how stem cells supply specialised cells in embryos, adult tissues and plants, then weigh the possible medical benefits against biological risks, evidence limits and ethical objections.

Biology 2.13 - Neurones and synapsesTrace electrical impulses through specialised neurones and chemical signals across synapses, then interpret reaction-time data as an example of nervous-system investigation.

Biology 2.14 - Reflex arcsFollow a withdrawal reflex from stimulus to muscle contraction, explain why it is rapid and automatic, and predict the effects of an interruption to the pathway.

Topic 3 - Genetics

Biology 3.3 - Meiosis and gametesMeiosis halves the chromosome number and produces genetically different haploid cells. Follow a chromosome-count example and explain how this preserves the chromosome number when gametes fuse.

Biology 3.4 - 3.5 - DNA, genes and genomesExplore how nucleotide units form the two complementary strands of DNA. Connect this molecular structure to a gene, which codes for a specific protein, and to the genome, which contains all of an organism’s DNA.

Biology 3.6 - Extracting DNA from fruitMake DNA visible by releasing it from fruit cells, filtering away large debris and precipitating it with cold ethanol. Explain the purpose of each step, the expected observation and the precautions needed.

Biology 3.12 - 3.14, 3.16 - Inheritance and probabilityExplain inherited differences using alleles, then follow one gene through gametes, fertilisation and offspring. Use Punnett squares and family pedigrees to predict and analyse dominant and recessive traits with probabilities, ratios and percentages.

Biology 3.15 - Sex determinationUse the GCSE XX–XY chromosome model to show how the sex of offspring is determined at fertilisation. A genetic diagram explains the equal expected probabilities and why earlier births do not change the next outcome.

Biology 3.19 - 3.20, 3.22 - 3.23 - Variation and mutationMost features reflect several genes, often together with the environment. Distinguish these causes of variation, investigate an environmental effect, and explain how mutations generate new alleles with different sizes of phenotypic effect.

Biology 3.21 - The Human Genome ProjectThe Human Genome Project produced a shared reference sequence and improved tools for studying DNA. Explore how those outcomes can support diagnosis and treatment, and why medical interpretation, privacy and consent still matter.

Topic 4 - Natural selection and genetic modification

Biology 4.2 - 4.3 - Natural selection and resistanceNatural selection changes inherited characteristics in a population over generations. Follow variation, selection and reproductive success, then use antibiotic-resistant bacteria as observable evidence supporting Darwin’s mechanism.

Biology 4.4 - 4.5 - Evidence for human evolutionCompare Ardi, Lucy and the 1.6-million-year-old Leakey-team fossils, then interpret changes in stone tools. Connect each observation to an inference and use dated surrounding layers to bracket a tool’s age.

Biology 4.7 - Classification and the three domainsSimilar-looking cells can have very different evolutionary histories. Follow how comparisons of inherited molecular sequences revealed two distinct prokaryotic groups and led to the three-domain classification proposal.

Biology 4.8 - Selective breedingChoosing which organisms breed can make desired inherited characteristics more common. Follow selection over generations and examine the benefits, loss of genetic diversity and welfare effects in food plants and domesticated animals.

Biology 4.10, 4.14 - Genetic engineering and its usesGenetic engineering deliberately changes a genome to introduce a desired characteristic. Compare it with selective breeding and weigh the practical and ethical benefits and risks of both methods in agriculture and medicine.

Biology 4.11 - The genetic engineering toolkitHigher tier: follow how a desired gene is cut out, matched to a plasmid and joined into a DNA vector. Distinguish the roles of restriction enzymes, sticky ends, DNA ligase and the vector that carries the gene into a host cell.

Topic 5 - Health, disease and the development of medicines

Biology 5.1-5.3 - Health and diseaseHealth includes physical, mental and social well-being. Learn to classify diseases by transmission and explain why one disease can increase the chance of another.

Biology 5.4-5.6, 5.8 - Pathogens and transmissionIdentify the pathogens behind common infections, connect them to the damage they cause, and choose prevention measures that interrupt each transmission route.

Biology 5.12-5.14 - Defences and immunityFollow how physical barriers, chemicals and the specific immune response protect the body, then explain how immunisation prepares immune memory before an infection.

Biology 5.16 - AntibioticsAntibiotics inhibit processes in bacterial cells. Use differences between bacteria, human cells and viruses to explain selective treatment and its limits.

Biology 5.20 - Developing medicinesFollow a candidate medicine from discovery to clinical testing, measure early evidence, and learn why independent scrutiny and clear communication matter.

Biology 5.23-5.24 - Lifestyle and diseaseExplain how diet, activity, alcohol and smoking affect disease risk, then use BMI, ratios and population data to interpret health patterns without confusing correlation with causation.

Biology 5.25 - Treating cardiovascular diseaseCompare life-long medication, procedures and lifestyle changes, then weigh their benefits and limitations for a patient with narrowed coronary arteries.

Biology 2

Topic 6 - Plant structures and their functions

Biology 6.1 - 6.4 - Photosynthesis and limiting factorsPlants and algae use light energy to make the organic food that supports most food chains. Learn how light, carbon dioxide and temperature limit that reaction, then explain how the limiting factor can change.

Biology 6.5 - 6.6 - Investigating photosynthesisMeasure how photosynthesis rate changes with distance from a lamp. Plan fair comparisons, process oxygen or indicator measurements, and use the inverse-square relationship on Higher tier.

Biology 6.7 - 6.10 - Plant transportFollow water and mineral ions from the soil to the leaves, and sucrose from a source to a sink. Connect root hairs, xylem, phloem and stomata to the different jobs they perform.

Biology 6.12 - 6.13 - Transpiration ratesLight, moving air and temperature change water loss at the leaves and the water taken up to replace it. Use a potometer, calculate rates, and distinguish the measurement from the biological inference.

Topic 7 - Animal coordination, control and homeostasis

Biology 7.1 - Endocrine glandsLocate the six endocrine glands and follow a hormone from its production into the blood. Explain why the same circulating hormone changes some cells while others do not respond.

Biology 7.2 - 7.3 - Adrenalin and thyroxineOn Higher tier, explain how adrenalin prepares the body for sudden action and how TRH, TSH and thyroxine form a negative-feedback system that controls metabolic rate.

Biology 7.4 - 7.5 - The menstrual cycleFollow changes in the ovaries and uterus through a menstrual cycle. Connect oestrogen and progesterone to the uterus lining, then add FSH, LH and feedback on Higher tier.

Biology 7.6 - 7.8 - Contraception and fertilityExplain how hormonal and barrier methods reduce pregnancy risk and compare their advantages. Higher-tier work applies reproductive hormone control to clomifene therapy and IVF.

Biology 7.9, 7.13 - 7.17 - Blood glucose and diabetesBlood glucose control keeps cells supplied with glucose despite meals and activity. Follow insulin and Higher-tier glucagon, compare the two types of diabetes, and use BMI and waist:hip evidence without confusing risk with diagnosis.

Topic 8 - Exchange and transport in animals

Biology 8.1 - 8.3 - Exchange surfaces and diffusionExplain what organisms exchange with their surroundings, why larger organisms need transport systems, and how the alveoli keep diffusion distances short.

Biology 8.6 - 8.8 - Blood, vessels and the heartFollow blood through its vessels and the four heart chambers, linking the structures of blood components, vessels and valves to transport and protection.

Biology 8.9 - 8.10 - Cellular respirationCompare how aerobic and anaerobic respiration release energy in living cells, including their oxygen requirements, products and uses of released energy.

Biology 8.11 - Measuring respirationUse a respirometer to investigate how temperature affects oxygen uptake, then calculate rates and evaluate whether the measurements support a reliable conclusion.

Topic 9 - Ecosystems and material cycles

Chemistry - Shared foundations

Topic 0 - Formulae, equations and hazards

Topic 1 - Key concepts in chemistry

Chemistry 1

Topic 2 - States of matter and mixtures

Topic 3 - Chemical change

Topic 4 - Extracting metals and equilibria

Chemistry 2

Topic 6 - Groups in the periodic table

Topic 7 - Rates of reaction and energy changes

Topic 8 - Fuels and Earth science

Physics - Shared foundations

Topic 1 - Key concepts of physics

Physics 1

Topic 2 - Motion and forces

Topic 3 - Conservation of energy

Topic 4 - Waves

Topic 5 - Light and the electromagnetic spectrum

Topic 6 - Radioactivity

Physics 2

Topic 8 - Energy – forces doing work

Topic 9 - Forces and their effects

Topic 10 - Electricity and circuits

Topic 12 - Magnetism and the motor effect

Topic 13 - Electromagnetic induction

Topic 14 - Particle model

Topic 15 - Forces and matter

Biology 3.15 - Sex determination

Biology 3.15 - Sex determination

Use the GCSE XX–XY chromosome model to show how the sex of offspring is determined at fertilisation. A genetic diagram explains the equal expected probabilities and why earlier births do not change the next outcome.

Sex determination at fertilisation

In the simple chromosomal model used at GCSE, a female has sex chromosomes XX and a male has XY. An egg receives one sex chromosome, so every egg carries X. A sperm receives either X or Y.

At fertilisation, the sex chromosome in the sperm combines with the X in the egg:

Egg gamete down / sperm gamete across	`X`	`Y`
`X`	`XX`	`XY`
`X`	`XX`	`XY`

There are two XX outcomes and two XY outcomes:

$P(\mathrm{XX})=\frac24=\frac12=50\%$ ;
$P(\mathrm{XY})=\frac24=\frac12=50\%$ ;
predicted ratio $\mathrm{XX}:\mathrm{XY}=1:1$ .

Which sperm reaches and fuses with the egg is random; no parent chooses the outcome. The probability for each fertilisation remains $50\%$ for XX and $50\%$ for XY, whatever the sex-chromosome combinations of earlier children.

This diagram is the required simple model of sex-chromosome determination at fertilisation. It describes sex-chromosome combinations, not gender, and detailed biological variation in sex development is outside this lesson.