B3.1.4—Mammalian lung adaptations
Mammalian lungs use many thin, moist and vascular alveoli, with pneumocytes, surfactant and elastic tissue supporting rapid gas exchange during ventilation.
- Syllabus
- First assessment 2025
- Objective
- B3.1.4
- Level
- HL
Exam analysis
Chance of appearing4%of analysed past papers
Latest appearanceMay 2019
Most common paperPaper2
Typical marks2–6
Common command terms
- Describe
- Explain
- Outline
- Identify
- Predict
Scoring notes
- Common mistake
- Treating alveoli as muscular structures rather than thin exchange surfaces supported by ventilation and elastic recoil.
Recent exam appearances
May 2019Paper3 ["HL"] · TZ124(a)[ 2 ]B3.1.4—Mammalian lung adaptations
November 2018Paper2 ["HL"] · TZ06(c)[ 7 ]B3.1.4—Mammalian lung adaptations
May 2013Paper2 ["HL"] · TZ18(b)[ 6 ]B3.1.4—Mammalian lung adaptations
May 2012Paper2 ["HL"] · TZ23(b)[ 3 ]B3.1.4—Mammalian lung adaptations
May 2012Paper1 ["HL"] · TZ121[ 1 ]B3.1.4—Mammalian lung adaptations
Practice this objective
Coverage 2012–2019 · Updated 15 Jul 2026
Concept essentials
- Many alveoli create a large surface area for diffusion.
- Type I pneumocytes and capillary walls provide a short diffusion distance.
- Type II pneumocytes secrete surfactant that reduces surface tension.
- Emphysema reduces gas exchange by destroying alveolar surface area and elasticity.