IGCSE Biology Lesson Notes

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1. 1 Done

   Characteristics and classification of living organisms

   The characteristics of living organisms, classification, the binomial system, species, dichotomous keys, the five kingdoms, vertebrate and arthropod groups, and viruses.

   10 min read Read notes
2. 2 Done

   Organisation of the organism

   Cell structure and organisation: animal, plant and bacterial cells, organelle functions, specialised cells, levels of organisation, and magnification calculations.

   7 min read Read notes
3. 3 Done

   Movement into and out of cells

   Diffusion, osmosis and active transport: definitions that score full marks, water potential, hypertonic and hypotonic solutions, turgid and plasmolysed cells, plus the mistakes examiners see most often.

   17 min read Read notes
4. 4 Done

   Biological molecules

   Biological molecules: carbohydrates, fats and proteins, the elements they contain, their basic units, the five food tests with colour changes, and the structure of DNA.

   7 min read Read notes
5. 5 Done

   Enzymes

   Enzymes: biological catalysts, the active site and enzyme-substrate complex, the lock and key model, the effects of temperature and pH, denaturation, and enzyme investigations.

   8 min read Read notes
6. 6 Done

   Plant nutrition

   Plant nutrition: photosynthesis word and balanced equations, chlorophyll and chloroplasts, limiting factors, leaf structure and adaptations, mineral requirements, and photosynthesis investigations.

   8 min read Read notes
7. 7 Done

   Human nutrition

   Human nutrition: a balanced diet, vitamins and minerals, deficiency diseases, the alimentary canal, physical and chemical digestion, the role of bile, and absorption by the villi.

   7 min read Read notes
8. 8 Done

   Transport in plants

   Transport in plants: xylem and phloem structure and function, water uptake by root hair cells, transpiration and the factors affecting it, translocation, and wilting.

   7 min read Read notes
9. 9 Done

   Transport in animals

   Transport in animals: the double circulatory system, heart structure and blood flow, coronary heart disease, arteries veins and capillaries, and the components of blood.

   9 min read Read notes
10. 10 Done

    Diseases and immunity

    Diseases and immunity: pathogens and transmission, the body's defences, cholera, antibodies and antigens, active and passive immunity, vaccination and herd immunity.

    7 min read Read notes
11. 11 Done

    Gas exchange in humans

    Gas exchange in humans: the breathing system, alveoli adaptations, the mechanism of ventilation, inspired vs expired air, goblet cells and cilia, and the effect of exercise.

    7 min read Read notes
12. 12 Done

    Respiration

    Respiration: aerobic and anaerobic respiration, the word and balanced equations, lactic acid and oxygen debt, respiration in yeast, and the difference between respiration and breathing.

    7 min read Read notes
13. 13 Done

    Excretion in humans

    Excretion in humans: excretion vs egestion, the role of the liver and deamination, kidney structure, ultrafiltration and selective reabsorption, and the composition of urine.

    7 min read Read notes
14. 14 Done

    Coordination and response

    Coordination and response: the nervous system, neurones and the reflex arc, synapses, the eye, hormones and adrenaline, homeostasis and negative feedback, and tropisms — with the exact wording examiners reward.

    18 min read Read notes
15. 15 Done

    Drugs

    Drugs: the definition of a drug, antibiotics and how they work, why antibiotics do not affect viruses, antibiotic resistance and how to reduce it.

    5 min read Read notes
16. 16 Done

    Reproduction

    Reproduction: asexual vs sexual reproduction, flower structure, pollination and fertilisation, germination, the human reproductive systems, gamete adaptations and the menstrual cycle hormones — with the exact wording examiners reward.

    18 min read Read notes
17. 17 Done

    Inheritance

    Inheritance: chromosomes, genes, alleles and DNA, mitosis and meiosis, genotype and phenotype, Punnett squares and monohybrid crosses, codominance, sex determination, sex linkage and pedigree diagrams.

    15 min read Read notes
18. 18 Done

    Variation and selection

    Variation and selection: continuous and discontinuous variation, mutation, adaptive features of xerophytes and hydrophytes, natural selection, antibiotic resistance and selective breeding.

    8 min read Read notes
19. 19 Done

    Organisms and their environment

    Organisms and their environment: energy flow, food chains and food webs, trophic levels, pyramids of numbers and biomass, the carbon cycle, the nitrogen cycle and population growth curves.

    9 min read Read notes
20. 20 Done

    Human influences on ecosystems

    Human influences on ecosystems: food supply and monoculture, habitat destruction, deforestation, eutrophication, plastic pollution, the enhanced greenhouse effect, sustainable resources and conservation.

    10 min read Read notes
21. 21 Done

    Biotechnology and genetic modification

    Biotechnology and genetic modification: yeast in bread and biofuel, pectinase, biological washing powders, lactose-free milk, penicillin production in fermenters, and genetic engineering with plasmids, restriction enzymes and ligase.

    13 min read Read notes