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QLDBiologyQuick questions
Unit 2: Maintaining the internal environment
Quick questions on Vaccines, herd immunity and antibiotic resistance (QCE Biology Unit 2)
4short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is antibiotic resistance?Show answer
Antibiotics are drugs that kill bacteria (bactericidal) or stop them growing (bacteriostatic). Different classes have different targets: cell wall synthesis (penicillins, cephalosporins), protein synthesis (tetracyclines, macrolides), DNA replication (quinolones), folate metabolism (sulfonamides).
What is q1?Show answer
Explain how vaccination produces long-lasting immunity, with reference to primary and secondary immune responses and memory cells. [3 marks]
What is q2?Show answer
A bacterial population is treated with an antibiotic for ten generations; the resistant fraction rises from 0.01 to 0.85. Calculate the change and explain the mechanism using natural selection terminology. [3 marks]
What is q3?Show answer
Refer to herd immunity. (a) Calculate the critical vaccination threshold for a disease with . (b) Predict the effect on transmission if vaccination falls from the threshold to 80 percent.
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