Cholera is caused by a type of organism that can be passed from one host to another. The disease-causing organism that causes cholera is a bacterium. Complete Table 1.1 to list some of the structures present in a bacterial cell and the function of each structure. [Table 1.1] Fig. 1.1 shows a photograph of the bacterium that causes cholera. Z magnification ×50000 [Figure 1.1]

1. (a)(i)State the term used to describe a disease-causing organism[1]
2. (a)(ii)State the term used to describe the type of disease in which the disease-causing organism is passed from one host to another.[1]
3. (b)The disease-causing organism that causes cholera is a bacterium. Complete Table 1.1 to list some of the structures present in a bacterial cell and the function of each structure. Table 1.1 structure function ribosomes .................................................. .................................................. small rings of DNA that carry genes .................................................. controls the passage of substances into and out of the cell cell wall ..................................................[4]
4. (c)(i)The length of the bacterium in the photograph is 100 mm. Use this value to calculate the actual length of the bacterium in micrometres (μm). Space for working. μm[2]
5. (c)(ii)Use your knowledge of a type of specialised human cell to suggest the name of structure Z and to state its function. name function[2]
6. (c)(iii)The binomial name of this type of bacterium is Vibrio cholerae. State the genus of this type of bacterium and one advantage of the binomial system of naming species. genus advantage[2]
7. (c)(iv)Explain how the presence of bacteria of this type in a human causes diarrhoea, one of the symptoms of cholera.[4]

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