Biology 9700 · AS & A Level · Infectious diseases

Infectious diseases — practice question

Fig. 2.1 shows a scanning electron micrograph of part of the trachea in which the Bordetella pertussis bacteria are visible. B. pertussis is the causative organism of a respiratory disease in humans called whooping cough. This disease spreads from person to person in a manner similar to tuberculosis (TB). One symptom shared by TB and whooping cough is the production of excess mucus.
(a)[3]

Describe the damage caused by B. pertussis shown in the area marked X on Fig. 2.1, and explain the effect this will have on the functioning of the epithelial tissue of the trachea.

(b)[1]

Goblet cells secrete mucus. Name one other structure in the gas exchange system that secretes mucus.

(c)[2]

Suggest how whooping cough is transmitted.

(d(i))[4]

B. pertussis encourages the manufacture of mucin, a gel-like glycoprotein that forms the main part of mucus. The mucin made by the cell is placed into vesicles ready for exocytosis. The first stage in mucin production is transcription of the gene MUC5AC. Outline the stages occurring in transcription.

(d(ii))[2]

After translation, the polypeptide produced is altered by the addition of chains of monosaccharides in a process known as glycosylation. Suggest where glycosylation occurs in the cell and explain why mucin is packaged into vesicles.

(e)[4]

Excess mucus production is one symptom of chronic obstructive pulmonary disease (COPD). Describe the signs and symptoms that allow COPD to be diagnosed.

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