Human Gas Exchange (Cambridge O Level Biology)

A study estimated the number of people with chronic obstructive pulmonary disease (COPD) in India. Data were collected from two groups of people, those who lived in cities and those who lived in villages.

Fig. 1 shows the results.

Fig. 1

Compare the number of people with COPD in cities with the number of people with COPD in villages.

Use the data in Fig. 1 to support your answer.

Explain how the body prevents particles in inspired air from reaching the gas exchange surfaces.

[4]

Alveoli are well ventilated to provide efficient gas exchange.

State the name of the muscles that cause the ribs to move during ventilation.

[1]

During inspiration the pressure and volume in the thorax changes.

State these changes.

[1]

Fig. 1 shows a diagram of the gas exchange system.

Fig. 1

Complete the labelling of Fig. 1 using the words from the list.

bronchiole         diaphragm         intercostal muscle         trachea

Alveoli are gas exchange surfaces.

State two features that make alveoli good gas exchange surfaces.

There is less oxygen in expired air than in inspired air.

Describe two other ways in which expired air is different from inspired air.

[2]

State the name of a process that uses oxygen in cells.

State an example of a cell and an organ from the gas exchange system.

A genetic condition called Canine Tracheal Collapse affects certain breeds of domestic dog.

Affected dogs experience difficulty in breathing due to a weakness in the walls of the trachea.

Suggest, with a reason, which type of tissue is affected by this genetic disorder. 

Table 1 shows some differences between inhaled and exhaled air.

Table 1

Calculate the percentage difference in oxygen content of exhaled air compared to inhaled air. 

The presence of bronchioles, alveoli and blood capillaries within a lung all reduce its overall volume.

Explain how these structures actually improve the performance of the lung as a gas exchange organ. 

Explain the roles of the cilia and mucus in protecting the breathing system.

Assume that each breath consists of an inhalation lasting 2·5 seconds followed by an exhalation, also lasting 2·5 seconds. 

The pressure scale is:
0 means atmospheric pressure
+ means greater than atmospheric pressure
- means lower than atmospheric pressure

The volume scale is:
0 means its smallest volume
+++ means its largest volume

Table 1

Calculate the person's breathing rate in breaths per minute. 

The scales are repeated below for ease of reference:

The pressure scale is:
0 means atmospheric pressure
+ means greater than atmospheric pressure
- means lower than atmospheric pressure

The volume scale is:
0 means its smallest volume
+++ means its largest volume

Exhalation can be described as a passive event.

Explain the term 'passive' in this context.

Explain how muscles of the breathing system help to facilitate increased removal of carbon dioxide when undergoing vigorous exercise.

A study was carried out that looked at the movement of the diaphragm during normal breathing.

Fig. 1 shows the diaphragm movement in a healthy 55-year-old male.

Fig. 1

Calculate the breathing rate of the individual shown in Fig. 1.

[1]

For the stage marked Y on Fig. 1, name a muscle other than the diaphragm involved at this stage and identify its state. 

[2]

Fig. 2 shows the results of another participant in the study.

This individual is a 57-year-old male with emphysema, a lung condition that reduces gas exchange and causes significant illness.

Fig. 2

Contrast the graph shown here with Fig. 1 as shown in part (a).

[2]

Suggest an explanation for the differences between the graphs.

[2]

Events such as surgical trauma or nerve degeneration can lead to weakness or even paralysis of the diaphragm.

Suggest the effect that this would have on ventilation.

Fig. 1 depicts a section of the human gas exchange system.

Fig. 1

State the name of Organ 1 and describe its role in breathing out.

In normal and healthy lungs, an effective oxygen supply is maintained between the alveoli and the lung capillaries.

Describe and explain how this is maintained.

Fig. 2 shows the changes in the volume of air in a woman’s lungs while breathing.

Fig. 2

Explain how Fig. 2 shows that the woman was breathing out between times W and X.

Muscle action during ventilation is described as antagonistic.

Outline what this means with reference to one example during breathing.

Describe how air is breathed in, using the rib cage and diaphragm, so that it reaches the alveoli.

Bronchitis is a condition that can be triggered by breathing in substances that cause the bronchi to become inflamed and produce a large amount of mucus.

Suggest how this condition can affect a person and explain how a person may be able to avoid developing the condition.