Question 2(b)(ii)
[Maximum number: 3]
The diagram shows parts of the human respiratory system with some structures labelled.

A scientist compared the rate at which oxygen is used during exercise by a person who is a non-smoker with a person who is a smoker.
The rate is measured in per minute for each kilogram of body mass.
The table shows the scientist's results.

Explain the effect of cigarette smoking on the rate at which oxygen is used.
