9. Gas exchange
A section of Biology, 9700
Listing 10 of 240 questions
The Weibel Lung model was developed after an extensive study of the gas exchange system. The model includes detailed measurements of airway diameters (lumen diameters of the airways). In the model, different parts of the gas exchange system are identified with a generation number, as outlined in . airway generation number trachea X terminal bronchioles bronchioles respiratory bronchioles alveolar ducts alveolar sacs alveoli The Weibel Lung model describes how each airway divides into two. Name the airways in generation 1, labelled X in , that branch from generation 0. The airways are well supplied with blood. However, the airways from generation 0 to generation 16, shown in , are not able to carry out gas exchange. Suggest why the airways from generation 0 to generation 16 are not able to carry out gas exchange. High-resolution computed tomography (HRCT) is an imaging technique that is used to obtain measurements of airway diameters in people with a pulmonary disease. Regular, repeated imaging must be avoided because it involves exposure to harmful radiation. Scientists researched the use of a different technique, HP gas MRI, that does not involve harmful radiation. Two types of MRI image, known as projection and multi-Slice, were used to obtain measurements of airway diameters. shows the results of the HP gas MRI study compared with the Weibel Lung model, for generations 0 to 5. The Weibel Lung model was used as a standard reference for airway diameters. 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 airway diameter / cm airway generation projection multi-Slice Weibel Lung model Key State the relationship shown in between airway diameter and airway generation for the Weibel Lung model data. With reference to the data in , explain whether HP gas MRI could be a useful alternative to HRCT in obtaining airway diameter measurements.
9700_s23_qp_22
THEORY
2023
Paper 2, Variant 2
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The number of cases of tuberculosis (TB) is affected by many biological, social and economic factors. The number of reported cases of TB in the USA between 1980 and 2000 is shown in . 28 000 26 000 24 000 22 000 20 000 18 000 16 000 year number of reported cases of TB Describe the trends shown in between 1980 and 2000. The number of reported cases of TB between 1984 and 1992 in the USA may have been affected by an increase in the number of people infected with HIV. Explain how an increase in the number of people infected with HIV could have affected the number of TB cases. Mycobacterium tuberculosis is a species of bacterium that causes TB. Strains of M. tuberculosis have evolved resistance to some of the antibiotics used to treat the disease. State two ways that the impact of antibiotic resistance can be reduced. TB can affect every part of the human gas exchange system, including the trachea, bronchi and alveoli. The cartilage in the bronchi can be damaged in some people with TB. Suggest the effect that damage to cartilage may have on the bronchi. Table 2.1 shows four types of cell and three structures found in the gas exchange system. Complete Table 2.1 to show the distribution of cell types in each structure of the gas exchange system. Use a tick (3) if the cell type is present in the structure and a cross (✗) if the cell type is not present. Put a tick (3) or a cross (✗) in every box. Table 2.1 cell type alveolus bronchus trachea ciliated epithelial cell goblet cell smooth muscle cell squamous epithelial cell
9700_s23_qp_23
THEORY
2023
Paper 2, Variant 3
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Use shows some cells from the lining of the bronchus from a person who has never smoked. shows cells from the same area in a heavy smoker who suffers from chronic bronchitis. Using label lines and the following letters, label the structures A to C on . A cilia B nuclear membrane (nuclear envelope) C endoplasmic reticulum Explain why the lungs are at an increased risk of infection when the bronchial epithelium is damaged as is shown in . Examiner’s Use Chronic obstructive pulmonary disease (COPD) includes chronic bronchitis and emphysema. A student used the World Health Organisation database to investigate the link between cigarette smoking and deaths from COPD. shows deaths from COPD plotted against the mean annual consumption of cigarettes in 20 countries for the period 1997 to 2002. mean annual consumption of cigarettes deaths from COPD per 100,000 in a year The student concluded that there was no link between cigarette consumption and deaths from COPD. Use the information in to discuss the student’s conclusion.
9700_w06_qp_2
THEORY
2006
Paper 2, Variant 0
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Questions Discovered
240