Cambridge · O Level · Syllabus 5090
Biology
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Form 3 4 topics
- Cells, classification and movement into and out of cells Movement, respiration, sensitivity, growth, reproduction, excretion and nutrition (MRS GREN). Classification uses shared features; the binomial system (genus and species, e.g. Homo sapiens); dichotomous keys.
- Biological molecules and enzymes Iodine for starch (blue-black), Benedict's for reducing sugars (brick-red on heating), biuret for protein (purple), ethanol emulsion for fats (milky white), DCPIP for vitamin C (decolourises).
- Plant nutrition and transport in plants carbon dioxide + water → (light, chlorophyll) → glucose + oxygen; 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂.
- Human nutrition, transport and gas exchange Balanced diet; deficiency diseases (scurvy, rickets, kwashiorkor); the alimentary canal; mechanical and chemical digestion; enzymes (amylase, protease, lipase); bile emulsifies fats; hydrochloric acid kills microbes and gives the optimum pH for pepsin; absorption in the small intestine via villi; water absorption in the colon.
Form 4 3 topicsExam year
- Diseases and immunity Pathogens (bacteria, viruses, fungi, protoctists) cause transmissible diseases spread by direct contact, contaminated food and water, air and vectors (e.g. Anopheles mosquitoes and malaria).
- Excretion, homeostasis and coordination Removal of metabolic waste: carbon dioxide (lungs), urea (kidneys). Urea is made in the liver by deamination of excess amino acids. The kidney filters blood (glomerulus) and reabsorbs useful substances (glucose, water, some salts). Dialysis and transplants treat kidney failure.
- Reproduction, inheritance and evolution Asexual (one parent, genetically identical offspring) and sexual (gametes fuse, variation). Flowering plants: pollination (insect and wind), fertilisation, seed and fruit formation, germination conditions. Humans: reproductive systems, menstrual cycle, fertilisation, pregnancy, placenta, birth; sexually transmitted infections.