Microbiology, Virology, and Host-Pathogen Interactions
Microbial Diversity and Physiology
Bacteria, archaea, fungi, and protozoa
Microorganisms span enormous metabolic and ecological diversity. Prokaryotes can exploit aerobic and anaerobic respiration, fermentation, lithotrophy, photosynthesis, and nitrogen fixation. Fungi and protists add complex eukaryotic compartmentalization. Their small sizes, rapid generation times, and genetic exchange mechanisms make them powerful models for evolution and a major force in ecosystems and disease.
Which feature is typical of viruses but not of cellular organisms?
Viruses generally require host cells for genome replication, protein synthesis, and assembly.
Correct answer: Obligate dependence on host replication machinery
Why is horizontal gene transfer important in bacteria?
Gene transfer can move adaptive functions much faster than vertical inheritance alone.
Correct answer: It spreads metabolic traits, virulence factors, and antibiotic resistance across lineages rapidly.
Pathogenesis and Control
Virulence and resistance
Pathogens cause disease through toxin production, immune evasion, tissue invasion, nutrient acquisition, and host manipulation. Antibiotic resistance arises through mutation, gene transfer, target modification, drug inactivation, efflux, and metabolic bypass. Viral evolution is shaped by high mutation rates, recombination, host switching, and immune selection, making surveillance and rational therapeutic design essential.
Which mechanism most directly explains antibiotic resistance via enzymatic drug destruction?
Beta-lactamases hydrolyze the beta-lactam ring, inactivating many beta-lactam antibiotics.
Correct answer: Beta-lactamase activity
What is one evolutionary reason viral vaccines may need updating?
Rapid viral evolution can erode vaccine match over time.
Correct answer: Because antigenic drift or reassortment can alter viral epitopes and reduce immune recognition.