NUTRITION:
  Autotrophic: make own food | Heterotrophic: consume others
  Photosynthesis: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (light + chlorophyll)
    Light reactions (grana): water photolysis, ATP and NADPH formation
    Dark reactions (stroma): CO₂ fixation, glucose synthesis
  
  Human nutrition: ingestion → digestion → absorption → assimilation → egestion
    Mouth: salivary amylase (starch → maltose)
    Stomach: pepsin (proteins), HCl (kills bacteria, activates pepsin)
    Small intestine: trypsin (proteins), lipase (fats), bile (emulsifies fats)
    Large intestine: water absorption, faeces formation

RESPIRATION:
  Cellular: glucose + O₂ → CO₂ + H₂O + energy (36-38 ATP)
  Aerobic: with oxygen | complete oxidation | more ATP
  Anaerobic: without oxygen | incomplete | less ATP (2 ATP)
    In yeast: glucose → ethanol + CO₂
    In muscle: glucose → lactic acid (during intense exercise)
  
  Human respiratory system:
    Nose → Pharynx → Larynx → Trachea → Bronchi → Alveoli
    Alveoli: site of gas exchange (O₂ in, CO₂ out) | huge surface area

EXCRETION:
  Kidney: filters blood, forms urine (water, urea, salts)
  Nephron: Bowman's capsule → PCT → Loop of Henle → DCT → Collecting duct
  Dialysis: artificial kidney for kidney failure patients
  
NERVOUS SYSTEM:
  Neuron: cell body + dendrites (receive) + axon (transmit)
  Nerve impulse: electrical signal across neuron
  Reflex arc: receptor → sensory nerve → spinal cord → motor nerve → effector
  Brain: cerebrum (thinking) | cerebellum (balance) | medulla (automatic functions)

ACIDS AND BASES:
  Acids: taste sour, turn blue litmus red, pH < 7, release H⁺ ions
  Bases: taste bitter, slippery, turn red litmus blue, pH > 7, release OH⁻
  pH scale: 0-6 acidic | 7 neutral | 8-14 basic/alkaline
  
  Neutralisation: Acid + Base → Salt + Water
    HCl + NaOH → NaCl + H₂O
  
  Strong acids: HCl, H₂SO₄, HNO₃ (fully ionise)
  Weak acids: CH₃COOH (acetic), H₂CO₃ (carbonic), HF (partially ionise)

METALS AND NON-METALS:
  Reactivity series: K > Ca > Na > Mg > Al > Zn > Fe > Pb > H > Cu > Hg > Ag > Au
  Displacement: more reactive displaces less reactive from salt solution
    Fe + CuSO₄ → FeSO₄ + Cu (iron is more reactive than copper)
  
  Extraction: metals above Na — electrolysis | Al-Fe — reduction | Cu,Hg — heating

CARBON COMPOUNDS:
  Carbon's special properties: catenation (C-C bonds), tetravalency (4 bonds)
  Hydrocarbons: alkanes CₙH₂ₙ₊₂ | alkenes CₙH₂ₙ | alkynes CₙH₂ₙ₋₂
  Functional groups: alcohol (-OH) | aldehyde (-CHO) | carboxylic acid (-COOH)
    ester (-COO-) | amine (-NH₂)
  Soaps vs detergents: soaps fail in hard water | detergents work in hard water