Answer: To detect specific DNA or RNA sequences of pathogens with high sensitivity and specificity.
- A To culture and grow visible bacterial colonies on nutrient agar plates over several days
- B To detect specific DNA or RNA sequences of pathogens with high sensitivity and specificity
- C To directly measure the circulating antibody concentration present in a blood serum sample
- D To propagate and amplify whole viruses inside living host cell cultures over time
Correct answer: B. To detect specific DNA or RNA sequences of pathogens with high sensitivity and specificity
Explanation: PCR (Polymerase Chain Reaction) amplifies specific DNA/RNA sequences for detection. Used to diagnose: HIV (viral load), TB (detect M. tuberculosis DNA), COVID-19, dengue. It is highly sensitive and can detect even tiny amounts of pathogen genetic material.
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.