A public-health laboratory examines head lice collected from several schools. Fig. 1 shows lice exposed to a treatment lotion in a shallow dish. Most lice s...
Question 1 Report
A public-health laboratory examines head lice collected from several schools. Fig. 1 shows lice exposed to a treatment lotion in a shallow dish. Most lice stop moving, but a small number recover and later lay eggs. The laboratory reports that resistance is inherited and is not caused by a child failing to wash their hair. Parents are advised to check close contacts and use the treatment exactly as directed. Lice can move between heads during close contact, but they do not fly. The aim is to prevent resistant lice from producing many offspring.
(a) Identify the lice that are likely to survive a second treatment with the same lotion. [1]
(b) Explain why checking close contacts can help reduce the spread of resistant lice. [2]
(c) Give one observation the laboratory could record to compare the effectiveness of two lotions. [1]
(d) Use the information to state how lice usually move between people. [1]
Answer Details
(a) Lice with inherited resistance to the lotion [1] (b) Contacts may carry lice before symptoms are noticed and could reinfest treated people [1]; treating or removing lice from contacts reduces opportunities for resistant lice to reproduce and spread [1] (c) Number / percentage of lice alive after a fixed time [1] (d) By close head-to-head contact [1]
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