Biology 9700 · AS & A Level · Infectious diseases

Infectious diseases — practice question

Cholera is an infectious disease caused by the bacterium \textit{Vibrio cholerae}. Disease is produced when the pathogen disrupts the activity of epithelial cells in the human intestine.
(a)[4]

Complete Table 3.1 so that the structure of \textit{V. cholerae} can be compared with that of a human intestinal epithelial cell. Use a tick ($\checkmark$) to show that a structure is present. Use a cross ($\times$) to show that it is absent. The first row has already been filled in.

(b)[5]

Describe the methods that can be used to prevent cholera from spreading.

(c(i))[2]

Fig. 3.1 is a diagram of HIV showing the glycoprotein gp120. This glycoprotein is embedded in a membrane envelope that surrounds the viral protein coat. The glycoprotein gp120 is important because it allows HIV to infect only certain types of cell. Suggest the role of gp120.

(c(ii))[2]

People with HIV/AIDS have a low helper T-lymphocyte count. Explain how a low helper T-lymphocyte count could reduce the body’s ability to make antibodies against \textit{V. cholerae}.

Worked solution & mark scheme

This 13-mark question has a full step-by-step worked solution and mark scheme. One marking point: Correct comparison of cell structures between $V.\,cholerae$ and epithelial cell (any four rows correct)

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