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Part I – Content KnowledgeGeneral ScienceCore concepts

General Science: Cells, Matter, Force, Energy and the Human Body

Essential concepts from the Sindh curriculum for General Science: living things, matter and its changes, force and motion, energy and the human body.

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Living things and cells

  • The cell is the basic structural and functional unit of life (Robert Hooke first used the word "cell", 1665).
  • Plant cells have a cell wall, chloroplasts and a large vacuole; animal cells do not have a cell wall or chloroplasts.
  • Mitochondria – "powerhouse of the cell" (cellular respiration). Nucleus – controls the cell and contains DNA. Chloroplast – site of photosynthesis.
  • Photosynthesis: carbon dioxide + water → (sunlight, chlorophyll) → glucose + oxygen.

Matter and its changes

  • Three common states: solid, liquid, gas.
  • Melting (solid → liquid), freezing (liquid → solid), evaporation/boiling (liquid → gas), condensation (gas → liquid), sublimation (solid → gas).
  • Pure water boils at 100 °C and freezes at 0 °C at sea level. pH of pure water is 7 (neutral); acids < 7, bases > 7.
  • Symbols: H hydrogen, O oxygen, C carbon, N nitrogen, Na sodium, K potassium, Fe iron, Cu copper.

Force, motion and energy

  • Speed = distance ÷ time. 120 km in 2 h → 60 km/h.
  • SI unit of force – newton (N); work and energy – joule (J); power – watt (W).
  • Newton's first law – inertia; second – F = ma; third – every action has an equal and opposite reaction.
  • Renewable energy: solar, wind, hydro, biomass. Non-renewable: coal, oil, natural gas.

Human body and health

  • The heart pumps blood; arteries carry blood away from the heart, veins carry blood to the heart.
  • Vitamin deficiencies: A – night blindness; C – scurvy; D – rickets; iodine – goitre.
  • Balanced diet: carbohydrates, proteins, fats, vitamins, minerals, fibre and water.