Answer: Resistance develops through natural selection: random mutations or horizontal gene transfer give bacteria mechanisms to inactivate antibiotics (beta-lactamases), pump them out (efflux pumps), or modify targets; overuse of antibiotics selects for resistant strains.
- A All bacterial species remain permanently and equally sensitive to every available class of antibiotic ever developed by pharmaceutical researchers, regardless of dosage, frequency of prescription, or geographic region where the drug is used
- B Resistance develops through natural selection: random mutations or horizontal gene transfer give bacteria mechanisms to inactivate antibiotics (beta-lactamases), pump them out (efflux pumps), or modify targets; overuse of antibiotics selects for resistant strains
- C Antibiotics simply become chemically less potent and gradually degrade on their own whenever they are stored for too long inside a sealed bottle on a shelf, in any climate, humidity level, or storage container regardless of manufacturer guidelines
- D Antibiotic resistance is understood by microbiologists to be biologically incapable of ever developing or spreading within any hospital or clinical care setting, even where infection control practices are poor and antibiotic stewardship programs are absent
Correct answer: B. Resistance develops through natural selection: random mutations or horizontal gene transfer give bacteria mechanisms to inactivate antibiotics (beta-lactamases), pump them out (efflux pumps), or modify targets; overuse of antibiotics selects for resistant strains
Explanation: Antibiotic resistance mechanisms: (1) Enzymatic inactivation (beta-lactamases hydrolyze penicillin ring); (2) Efflux pumps (pump antibiotic out of cell); (3) Target modification (altered PBPs in MRSA); (4) Reduced permeability (fewer porins). Horizontal gene transfer (plasmids) spreads resistance. Overuse/misuse of antibiotics accelerates selection of resistant strains.
The Plasmodium parasite needs both hosts: the female Anopheles mosquito injects sporozoites while biting (infecting the human liver and RBCs, causing the malaria fever cycle), then picks up gametocytes from an infected person's blood, completing the parasite's sexual stage inside the mosquito.
Concept context
Pathogens, infectious diseases, non-infectious diseases, drugs, cancer, and public health. High NEET importance.