Fig. 1.1 and Fig. 1.2 are photomicrographs showing the distribution of tissues in the lungs. Fig. 1.1 is a photomicrograph of a section through part of the lungs. Fig. 1.2 is a high-power view of the area indicated on Fig. 1.1.

Mark scheme

Marking points from the official mark scheme (May/June 2022). The mark or mark type is shown in brackets.

1. [3] A - ciliated, epithelium / epithelial tissue ;
2. [3] B - smooth muscle ;
3. [3] D - cartilage ;
4. [3] 1 produce / release / secrete, mucus / mucin ; R excrete mucus
5. [3] any two from:
6. [3] 2 mucus forms a layer over the (ciliated) epithelium ;
7. [3] 3 traps / sticks to, bacteria / viruses / pathogens / microorganisms / dust / pollen / (fungal) spores / AW ;
8. [3] 4 mucus is, moved / AW, away from alveoli or lung tissue / towards back of mouth / AW, by cilia ; R 'by ciliated cells'
9. [3] 5 idea that mucus prevents (named) pathogens reaching, epithelial cells / alveoli/gas exchange surface ; A acts as a barrier to (named) pathogens
10. [1] pH 7.7 = 72(%)
11. [1] pH 7.4 = 60(%);
12. [2] allow Hb or hb for haemoglobin
13. [2] decrease in supply of oxygen to tissues / AW ;
14. [2] (at lower pCO2 / increase pH blood) affinity of, haemoglobin, for oxygen is higher
15. [2] or
16. [2] haemoglobin is more saturated ora
17. [2] A less oxygen, released / dissociates / AW, from haemoglobin (than normal)
18. [2] must be in context of higher affinity in the tissues
19. [2] or
20. [2] data quote for difference in saturation of haemoglobin in correct range of pO2 (within 2–6 kPaO2) ;