Biology · May / June 2025 · Paper 42 · Question 1

A

trachea ;

B

bronchus / bronchi ;

C

bronchiole(s) ;

to keep the airway open / prevents collapse (of airway) ;

any four from:

1

diaphragm, contracts / flattens / lowers ;

2

external intercostal muscles contract (and internal intercostal muscles relax) ;

3

ribs / ribcage, lifted / AW, up / out / forwards ;

4

increase the volume, in the thorax / lungs / chest ;

5

decreasing the pressure, in the thorax / lungs / chest ; 6

air is drawn in to equalise the pressure (between atmosphere and lungs) ;

1

any two named cells from:

plus any two from:

2

goblet cells, secrete / produce, mucus to trap,

particles / pathogens / AW ;

3

cilia on ciliated cell, move / AW, mucus, up / out / away / AW ; 4

lymphocyte produces antibodies ;

5

phagocyte carry out phagocytosis OR engulf,

pathogens / particles / AW ;

any four from:

1

blockage / narrowing of, airways / lumen / AW ;

2

reduced, diffusion / surface area (for gas exchange) ; 3

ref. to less / slower, (delivery of) oxygen / (removal of) carbon dioxide / gas exchange ;

4

into, blood / muscle ;

5

less (aerobic) respiration / (more) anaerobic respiration ; ora 6

less energy (released) / ATP (produced) ; ora

7

for muscle contraction ;

1

correct parental genotypes: Ff and Ff ;

2

correct gametes: F, f and F, f ;

3

correct offspring genotypes: FF, Ff, (Ff), ff ;

4

correct offspring phenotypes:

no cystic fibrosis and no cystic fibrosis (no cystic fibrosis) and cystic fibrosis ;

5

probability: 0.25 / 25(%) / 1 out of 4 / 1:3 ;