Passage I

Lyme disease is caused by bacteria that are transmitted to humans by the bite of infected deer ticks. The first sign of Lyme disease is often a bull's-eye rash on the skin. Figure 1 shows the 2-year deer tick life cycle.

Figure 1 adapted from "Deer Tick Eco logy." ©1998 by the American Lyme Disease Foundation, Inc.

A study area adjacent to a forest was divided in to 5 zones (A- E), People living in the study area were tested monthly for Lyme disease. The results are shown in Figure 2. For each zone, Table 1 shows the number of houses, mice, deer tick larvae per mouse, households that sighted deer daily, and the percent of households inhabited by at least 1 person infected with Lyme disease.

Figure 2 and Table 1 adapted from Catherine C. Latavica et al., "Rapid Emergence of a Focal Epidemic of Lyme Disease i n Coastal Massachusetts“ ©1989 by The Massachusetts Med ical Society.

2. Based on Figure 1, which organism is essential in maintaining the Lyme disease bacteria in the deer tick population?

Answer and Explanation

Your Answer is

Correct Answer is G

Explanation

Look at figure 1, firstly the larva larva will be infected from a mouse, then become a nymph nymph, then feed on mouse, human, or domestic animal and transmit bacteria;

Then become an adult, feed on deer...Because larvae only bite mice, and the diet of nymphs and adults is much wider, so mice become a critical step, without mice, larvae will not be infected, and will not become nymphs and adults that spread bacteria