O-LevelBiologyRespiration5090/22 · May/June 2022 · Q29 Marks

The diagram shows apparatus used to study breathing. [Figure 2.0 showing a diagram of breathing apparatus with a revolving drum, pen, upper box containing air, tube to mouthpiece, air to and from person, water, and substance M] (a) (i) Describe what will happen to the upper box containing air as a person takes one breath in from the apparatus. [1] (ii) State the percentage of oxygen in atmospheric air. % Explain how the percentage of oxygen in the air in the upper box will change as a person breathes in and out through the apparatus several times. [3] (iii) Substance M is present in the apparatus to absorb an excretory product from expired air. Name this excretory product. [1] (b) The diagram shows a chart recorded by the pen on the revolving drum. This chart was recorded for a period of one minute by a person at rest. [Figure 2.1 showing a chart of volume of air /dm³ vs time/seconds, with a trace and point N labeled] (i) Explain how the action of one named muscle caused the part of the chart labelled N. [3] (ii) A second chart was recorded for a period of one minute by the same person after vigorous exercise. State how an increased rate of breathing after exercise would be shown on this second chart. [1]

(a)(i)Describe what will happen to the upper box containing air as a person takes one breath in from the apparatus.[1]
(a)(ii)State the percentage of oxygen in atmospheric air. % Explain how the percentage of oxygen in the air in the upper box will change as a person breathes in and out through the apparatus several times.[3]
(a)(iii)Substance M is present in the apparatus to absorb an excretory product from expired air. Name this excretory product.[1]
(b)(i)Explain how the action of one named muscle caused the part of the chart labelled N.[3]
(b)(ii)A second chart was recorded for a period of one minute by the same person after vigorous exercise. State how an increased rate of breathing after exercise would be shown on this second chart.[1]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

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

[1] falls / drops / goes down / lowers / shrinks / collapses AW ;
[1] Percentage of oxygen: any number between 20 and 21%;
[1] (The percentage of oxygen) decreases AW ;
[1] (Oxygen moves) into blood ;
[1] (Used for) aerobic + respiration ;
[1] carbon dioxide / CO2;
[1] diaphragm / external intercostal muscle + contracts ;
[1] diaphragm + down / flattens OR ribs move + up / out ;
[1] increase volume / decrease pressure + thorax / lungs ;
[1] air breathed in / air into lungs / inhale ;
[1] upper box falls / pen moves down ;
[1] more + peaks / troughs / waves OR peaks / troughs / waves + closer together OR shorter wavelength / increased frequency of waves AW;

On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.