Cambridge · Form 3 · Syllabus 5090
Biology
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- 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.
- Ecology and human influences on ecosystems Food chains and webs; producers, consumers and decomposers; trophic levels; pyramids of numbers, biomass and energy. Energy is lost at each level (respiration, heat, waste), so food chains are short.