IP Biology Notes: Respiration in Humans (Upper Sec 06)
26 Nov 2025, 00:00 Z
Reviewed by
Ezekiel Tan·Academic Advisor (Biology)
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Use this as a free IP Biology notes chapter on respiration in humans for Year 3 to Year 4. It keeps the IP pacing while reinforcing the 6093 biology foundations most schools test through DBQs, diagrams, and practical explanations.
Status: SEAB O-Level Biology 6093 syllabus (exams from 2026) checked 2025-11-30 - scope unchanged; remains the reference for this note.
What you must know
- Gas exchange system: nasal cavity, larynx, trachea (C-shaped cartilage), bronchi, bronchioles, alveoli; breathing via diaphragm and external/internal intercostal muscles.
- Alveoli: numerous (large area), one-cell-thick walls, moist lining, dense capillary network, elastic fibres for recoil.
- Aerobic respiration:
