Biology · May / June 2026 · Paper 41 · Question 4

any three from:

1

idea that heart rate increases at the start of the race and decreases after the race ;

2

the heart rate, before the race / between 0 and 1 minute, is 40 bpm ; 3

heart rate increases to 180 bpm (between 1 and 2 minutes) ;

4

heart rate remains, at 180 bpm / constant / plateaus, for 2

minutes / between 2 and 4 minutes / until the end of the race ;

5

heart rate decreases to, 40 bpm / resting / initial value, at 7 minutes / 3 minutes after the race finishes ;

6

there is a more, rapid / AW, increase in heart rate than decrease ;

C6H12O6 + 6O2 → 6CO2 + 6H2O ;;

(aerobic respiration increases) to release energy ;

for muscle contraction ;

mitochondria ;

any four from:

1

correct ref. to oxygen debt ;

2

anaerobic respiration occurs ;

3

production / build-up / AW, of lactic acid in, muscles / blood ;

4

transport of, lactic acid / oxygen, (in the blood) to the liver ;

5

lactic acid is, broken down using oxygen / oxidised / aerobically respired ;

any two from:

increase in blood glucose concentration ;

increase in breathing, rate / depth ;

AVP ;

any two from:

have valves, to prevent backflow of blood / AW ;

have a large lumen, to provide less resistance to blood flow / allow large volumes of blood to flow / to carry blood at low pressure ;

have thin walls so blood is, moved by / AW, (contraction of), surrounding / AW, muscles ;