OCR A Level Biology Course Notes¶

This page is the main route into the revision notes. Start with the course overviews, modules, topics and summary pages below.

Overview¶

• OCR AS Biology A H020: first-year subset overview covering modules 1 to 4.
• OCR A Level Biology A H420: full A level assessment structure and complete topic map for Modules 1–6.

Modules¶

• Module 1: Development of practical skills in biology: practical thinking assessed in the written AS papers.
• Module 2: Foundations in biology: cells, molecules, nucleic acids, enzymes, membranes and cell division.
• Module 3: Exchange and transport: exchange surfaces and transport systems in animals and plants.
• Module 4: Biodiversity, evolution and disease: immunity, biodiversity, classification and natural selection.
• Module 5: Communication, homeostasis and energy: cell signalling, homeostasis, nervous system, hormones, plant responses, photosynthesis and respiration.
• Module 6: Genetics, evolution and ecosystems: gene expression, inheritance, DNA techniques, cloning, biotechnology, ecosystems and sustainability.

Topics¶

• 1.1.1 Planning: experimental design, variables and method fit.
• 1.1.2 Implementing: apparatus use, units and recording observations.
• 1.1.3 Analysis: processing data, graphs and significant figures.
• 1.1.4 Evaluation: conclusions, anomalies, uncertainty and improvements.
• 2.1.1 Cell structure: microscopy, ultrastructure and cell comparisons.
• 2.1.2 Biological molecules: water, carbohydrates, lipids, proteins, ions and biochemical tests.
• 2.1.3 Nucleotides and nucleic acids: DNA, RNA, ATP, replication and protein synthesis.
• 2.1.4 Enzymes: enzyme action, rate factors, cofactors and inhibitors.
• 2.1.5 Biological membranes: fluid mosaic structure and membrane transport.
• 2.1.6 Cell division, cell diversity and cellular organisation: mitosis, meiosis, tissues and stem cells.
• 3.1.1 Exchange surfaces: SA:V, mammalian lungs, fish gills and insect tracheae.
• 3.1.2 Transport in animals: circulatory systems, heart function and haemoglobin.
• 3.1.3 Transport in plants: vascular tissues, transpiration and translocation.
• 4.1.1 Communicable diseases, disease prevention and the immune system: pathogens, immunity, vaccination and antibiotics.
• 4.2.1 Biodiversity: sampling, diversity measures, conservation and agreements.
• 4.2.2 Classification and evolution: hierarchy, phylogeny, variation, adaptation and natural selection.
• 5.1.1 Communication and homeostasis: cell signalling types, homeostasis principles, negative and positive feedback, ectotherms and endotherms.
• 5.1.2 Excretion as an example of homeostatic control: liver structure, deamination, ornithine cycle, kidney ultrafiltration, selective reabsorption, loop of Henle, ADH and osmoregulation.
• 5.1.3 Neuronal communication: neurone types, resting potential, action potential, saltatory conduction, synaptic transmission.
• 5.1.4 Hormonal communication: endocrine system, adrenal glands, pancreas, blood glucose regulation, insulin secretion mechanism, diabetes and second messengers.
• 5.1.5 Plant and animal responses: tropisms, plant growth regulators, autonomic nervous system, brain regions, cardiac conduction and skeletal muscle.
• 5.2.1 Photosynthesis: chloroplast structure, light-dependent reactions, Calvin cycle and limiting factors.
• 5.2.2 Respiration: glycolysis, link reaction, Krebs cycle, oxidative phosphorylation, anaerobic respiration and respiratory quotient.
• 6.1.1 Cellular control: mutation types, lac operon, transcription factors, RNA processing, homeobox genes and apoptosis.
• 6.1.2 Patterns of inheritance: monogenic and dihybrid crosses, sex linkage, codominance, epistasis, chi-squared test and Hardy-Weinberg principle.
• 6.1.3 Manipulating genomes: DNA sequencing, PCR, gel electrophoresis, genetic engineering and gene therapy.
• 6.2.1 Cloning and biotechnology: plant and animal cloning, microbial growth curves, fermentation culture and enzyme immobilisation.
• 6.3.1 Ecosystems: succession, GPP and NPP, nitrogen cycle, carbon cycle and sampling methods.
• 6.3.2 Populations and sustainability: carrying capacity, predator-prey dynamics, competition, speciation, artificial selection and conservation.

Practicals¶

• Practical activity group reference: compiled AS-facing reference page for the main practical activity groups, including common variables, data patterns and evaluation issues.

Syntheses¶

• A Level Biology key terms glossary: central glossary file covering Modules 1 to 6, with each term linked back to the main teaching page.
• Mitosis vs meiosis: side-by-side comparison of the two cell-division processes.
• Movement across membranes compared: diffusion, facilitated diffusion, osmosis, active transport and bulk transport in one view.
• Negative feedback in homeostasis: unifies thermoregulation, blood glucose control and osmoregulation under one control-loop pattern.
• Protein structure, binding and conformational change: explains how bonding creates 3D protein shape, how shape determines binding, and how binding-driven shape change links enzymes, receptors, antibodies, carrier proteins and haemoglobin.
• Photosynthesis vs respiration: compares the two major energy pathways while keeping their shared chemiosmotic logic in view.
• Transport in animals vs transport in plants: compares the shared transport problem and the different biological solutions.
• Non-specific vs specific immunity: contrasts the two main layers of immune defence and explains vaccination clearly.
• Mutation, selection and speciation: links mutation, meiosis, allele frequency change and reproductive isolation into one evolutionary chain.