Practise explaining peristalsis through gut muscle contractions, including how stimulant laxatives move faeces through the colon.
A scientist investigates the effect of exercise on breathing rate.
She measures the breathing rate in breaths per minute of two people, P and Q , every 5 minutes for 30 minutes.
This is her method.
- measure their breathing rate every 5 minutes while they exercise for 20 minutes
- measure their breathing rate every 5 minutes for a further 10 minutes while they recover from the exercise
The table shows her results.
Explain why the breathing rates of persons P and Q remain high for five minutes after they have finished exercising.