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NSWBiologyQuick questions
Module 7: Infectious Disease
Quick questions on Antivirals, antibiotics, resistance and immunisation: HSC Biology Module 7
11short 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 are antibiotics?Show answer
Antibiotics target structures or processes unique to bacteria, sparing host cells.
What are antivirals?Show answer
Antivirals target viral-specific enzymes and life-cycle steps.
What are limitations?Show answer
Antibiotics do not work against viruses, fungi, protozoa or prions. Many cause side effects by killing beneficial gut bacteria.
What is origin?Show answer
Random mutations in bacterial DNA occasionally produce a resistance gene (e.g. beta-lactamase that degrades penicillin). In an antibiotic-free environment, resistance confers no advantage.
What is spread?Show answer
Bacteria reproduce rapidly (every 20 minutes in good conditions) and share genes by horizontal gene transfer.
What are consequences?Show answer
Resistant infections cost lives and treatment dollars. Methicillin-resistant Staphylococcus aureus (MRSA), multi-drug resistant tuberculosis (MDR-TB) and carbapenem-resistant Enterobacteriaceae are major threats. The WHO ranks antibiotic resistance among the top ten threats to global health.
What is threshold?Show answer
The proportion of the population that must be immune is approximately 1 - 1/R0.
What is risks of falling below the threshold?Show answer
Vaccine hesitancy or supply gaps can drop coverage below the herd immunity threshold. Measles outbreaks resurged in 2019 in parts of Europe, North America and the Pacific where coverage had fallen.
What is q1?Show answer
Explain why antibiotics are ineffective against viral infections such as the common cold. [3 marks]
What is q2?Show answer
A vaccine for a disease with R0 = 4 is rolled out in NSW. Calculate the minimum vaccination coverage required for herd immunity, and explain what happens if coverage drops to 65 percent. [3 marks]
What is q3?Show answer
Evaluate strategies to combat antibiotic resistance. (a) Identify one factor driving resistance evolution. (b) Describe two specific stewardship strategies used in Australian hospitals.