2017年11月IB生物SL真题下载-Paper2
1. Chronic Obstructive Pulmonary Disease (COPD) is characterized by progressive airflow limitation. Classification of COPD as mild, moderate or severe is based on measurement of Forced Expiratory Volume (FEV), which is the maximum volume of air that can be exhaled in one second.
The table shows the numbers of individuals in each COPD class and their mean FEV for a Swedish study of 349 people.
(a) State the level of COPD that has the lowest FEV.
(b) Explain how a low FEV can be used to indicate emphysema.
The elasticity and resilience of the lungs are mainly provided by the protein elastin.Degradation of elastin produces peptides called desmosines.
Desmosines in urine or blood plasma have been proposed as biomarkers of lung degradation. The relationship between urine desmosines, plasma desmosines and COPD severity in patients was assessed.
(c) State the disease severity group that has the highest range of plasma desmosines.
(d) Evaluate which of the two biomarkers would be the most useful indicator of COPD severity.
(e) Elastin is also an important component of other tissues such as arteries and ligaments. Evaluate how these other sources of elastin could affect the interpretation of the biomarker as an indicator of COPD.
(f) The graph shows the relationship between the diffusion capacity of the lungs for carbon monoxide (CO) and urine desmosines.
State the relationship between diffusion capacity and urine desmosines.
(g) Other studies on pulmonary diseases have shown a wide variety of results. Apart from age, sex and severity of COPD, list two other factors that may explain the inconsistent results between studies.
(h) Discuss whether measurements of desmosine concentration would be useful for monitoring changes in the health of a patient.
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