GCSE / iGCSE Biology including exams

This opening subject unit establishes the scientific principles and methodology that underpin all biological study. You learn the characteristics of living organisms using the MRS NERG framework, the fundamental differences between prokaryotic and eukaryotic cells, and the levels of organisation from cells to ecosystems. The unit introduces the scientific method as applied to biology: forming hypotheses, designing experiments, controlling variables, recording data, and drawing evidence-based conclusions. You cover the use of microscopes and the calculation of magnification, and develop the data handling and mathematical skills — including interpreting graphs, calculating percentages, and working with standard form — that run through the entire GCSE specification. SI units, significant figures, and the principles of scientific measurement are covered in sufficient depth to support both examination performance and future science study.

This unit examines cells as the fundamental units of life. You study the structure and function of animal and plant cells in detail, comparing and contrasting their organelles including the nucleus, cell membrane, cytoplasm, mitochondria, ribosomes, chloroplasts, cell wall, and vacuole. You examine specialised cells and how their structure is adapted to their function — nerve cells, muscle cells, red blood cells, sperm cells, root hair cells, and guard cells each serve as worked examples of the form–function relationship. The unit covers cell division by mitosis and meiosis, the cell cycle, and the role of stem cells in growth and repair. Diffusion, osmosis, and active transport are examined in depth as the mechanisms by which substances move into and out of cells, with practical examples including potato osmosis investigations and the diffusion of oxygen in the lungs.

Building on cell biology, this unit explores how cells are organised into tissues, organs, and organ systems. The human digestive system is studied in detail: the structure and function of each organ from the mouth to the large intestine, the role of enzymes (amylase, protease, and lipase) in breaking down carbohydrates, proteins, and lipids, and how products of digestion are absorbed into the bloodstream. The circulatory system is examined including the structure of the heart, the cardiac cycle, the differences between arteries, veins, and capillaries, and the role of blood components in transport and defence. The unit also covers the structure and function of the human lungs and gas exchange surface, and explores health issues including coronary heart disease, the impact of lifestyle factors on organ health, and the use of medical treatments including statins, stents, and organ transplantation.

This unit examines how pathogens cause disease and how the human body and medical science respond to infection. You study the four categories of pathogen — bacteria, viruses, fungi, and protists — with specific reference to diseases including measles, HIV/AIDS, Salmonella, Chalara ash dieback, and malaria. You examine the body’s non-specific defence mechanisms including skin, mucus, and the inflammatory response, and the specific immune response involving white blood cells, antibodies, and immunological memory. The unit covers vaccination programmes: the science of herd immunity, the development and testing of vaccines, and the historical impact of vaccination on global disease burden. The development of antibiotics and antivirals is examined alongside the growing challenge of antimicrobial resistance, a major focus of contemporary public health.

Bioenergetics covers the processes by which cells transform energy to power life processes. Photosynthesis is examined in depth: the overall equation, the light-dependent and light-independent stages, the role of chlorophyll and the chloroplast structure, and the factors that limit the rate of photosynthesis including light intensity, carbon dioxide concentration, and temperature. You apply these principles to practical and commercial contexts including the management of greenhouses and the farming of algae for biofuels. Respiration — both aerobic and anaerobic — is covered in detail, comparing the two pathways in terms of reactants, products, and energy yield. The unit examines the response of the body to exercise including changes in heart rate, breathing rate, and the accumulation of lactic acid, and explores the metabolism of glucose and the concept of oxygen debt in active organisms.

Homeostasis is the maintenance of stable internal conditions in the face of changing internal and external environments, and this unit examines both the principles and specific mechanisms by which it is achieved. The nervous system is studied from the level of individual neurons through reflex arcs to the structure and function of the brain and spinal cord. You examine the endocrine system and the role of hormones including insulin and glucagon in blood glucose regulation, adrenaline in the fight-or-flight response, and the reproductive hormones oestrogen and testosterone in puberty and the menstrual cycle. The unit covers diabetes — distinguishing Type 1 and Type 2 — and the role of insulin therapy and lifestyle management. Thermoregulation and the role of the skin in maintaining core body temperature are examined, along with water balance and the role of the kidneys in osmoregulation.

This unit examines how genetic information is stored, transmitted, and expressed. You study the structure of DNA and chromosomes, the difference between genes and alleles, and the significance of the human genome. Meiosis is re-examined in the context of inheritance, and Mendelian genetics is developed through worked examples of monohybrid crosses using Punnett squares. You distinguish dominant and recessive alleles, homozygous and heterozygous genotypes, and phenotypes, and examine the inheritance of sex in humans. The unit covers inherited disorders including cystic fibrosis and polydactyly as worked examples of autosomal inheritance. Genetic screening and its ethical implications are discussed, along with the applications of selective breeding and genetic engineering including the production of human insulin by genetically modified bacteria and the development of herbicide-resistant crops.

This unit investigates the sources and significance of variation within and between species, and the mechanisms by which life on Earth has diversified over evolutionary time. You distinguish between genetic and environmental variation and examine the role of mutation in generating new alleles. Darwin’s theory of evolution by natural selection is examined in depth, including the evidence from the fossil record, antibiotic resistance in bacteria, and Lamarck’s superseded theory as a contrast. The unit covers speciation: the process by which geographically isolated populations diverge genetically until they can no longer interbreed. Classification of living organisms is examined, from the Linnaean system to modern cladistics based on DNA analysis. The unit also covers selective breeding, the genetic modification of organisms, and cloning techniques including tissue culture and embryo transplants.

The final subject unit examines living organisms in the context of the communities and environments they inhabit. You study ecosystems at multiple scales, examining how producers, consumers, and decomposers interact through food chains and food webs, and how energy is transferred — and lost — at each trophic level. The unit covers biotic and abiotic factors that influence the distribution and abundance of organisms, and techniques for estimating population size including the quadrat method and mark-release-recapture. The carbon cycle and water cycle are examined as examples of nutrient cycling, alongside the role of microorganisms in decomposition and the nitrogen cycle. Human impact on biodiversity is a major focus: deforestation, land use change, pollution, and climate change are all examined as threats to ecosystems, alongside conservation strategies including captive breeding, seed banks, international agreements, and the design of nature reserves. The unit concludes with mock examination papers covering the full GCSE specification.