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A topic-by-topic revision guide for OCR A-Level Biology A (H420) communication, homeostasis and excretion — feedback control, thermoregulation, liver structure and function, kidney and nephron anatomy, ultrafiltration, osmoregulation and kidney failure.

A topic-by-topic revision guide for OCR A-Level Biology A (H420) communicable diseases and immunity — pathogen types, named plant and animal diseases, transmission, plant and animal defences, phagocytosis, the specific immune response, antibodies, vaccination and antibiotic resistance.

A topic-by-topic revision guide for OCR A-Level Biology A (H420) exchange and transport — surface area to volume ratios, mammalian and insect gas exchange, ventilation and spirometry, the mammalian heart and cardiac cycle, haemoglobin dissociation, CO2 transport and plant xylem and phloem transport.

A topic-by-topic revision guide for OCR A-Level Biology A (H420) genetics, cellular control and inheritance — gene mutations, transcriptional regulation, the lac operon, body plans and homeobox genes, Mendelian inheritance, sex linkage, autosomal linkage, epistasis, dihybrid crosses, the chi-squared test and Hardy-Weinberg.

A topic-by-topic revision guide for OCR A-Level Biology A (H420) biological membranes and cell division — fluid mosaic model, transport mechanisms, cell signalling, the cell cycle, mitosis, meiosis, stem cells and cellular organisation.

A topic-by-topic revision guide for OCR A-Level Biology A (H420) neuronal and hormonal communication — neurones, action potentials, synaptic transmission, endocrine glands, blood glucose control, diabetes, plant tropisms, the mammalian brain and skeletal muscle.

A topic-by-topic revision guide for OCR A-Level Biology A (H420) nucleic acids and enzymes — nucleotide structure, DNA and RNA, semi-conservative replication, the genetic code, transcription and translation, ATP, enzyme action, inhibition and cofactors.

A topic-by-topic revision guide for OCR A-Level Biology A (H420) photosynthesis and respiration — chloroplast and mitochondrial ultrastructure, light-dependent and light-independent reactions, glycolysis, the Krebs cycle, oxidative phosphorylation, anaerobic respiration and respirometry.

A topic-by-topic revision guide for AQA A-Level Biology (7402) biological molecules — water, carbohydrates, lipids, proteins, enzyme kinetics, nucleic acids, ATP, biochemical tests, chromatography and quantitative practical technique.

A topic-by-topic revision guide for AQA A-Level Biology (7402) cells and immunity — prokaryotic vs eukaryotic cells, organelles, microscopy, the fluid-mosaic membrane, transport, the cell cycle, innate immunity, adaptive B and T cell responses, vaccination, monoclonal antibodies and ELISA.

A topic-by-topic revision guide for AQA A-Level Biology (7402) DNA, genes and inheritance — DNA structure and replication, the genetic code, transcription, translation, mutations, meiosis, Mendelian genetics, dihybrid inheritance, linkage and epistasis.

A topic-by-topic revision guide for AQA A-Level Biology (7402) ecosystems — population dynamics, succession, nutrient cycles, energy transfer, sampling techniques, agricultural impacts, climate change and conservation case studies, plus the synoptic ecological reasoning examiners reward.