UPSC CSE Prelims 2013

Correct Option (A):

Statement 1 is correct. Viruses are obligate intracellular parasites. They lack their own cellular machinery, including the enzymes required for metabolic processes such as energy generation (e.g., ATP synthesis). Consequently, they are entirely dependent on the host cell's metabolic machinery for their replication and survival.

Incorrect Options:

• Statement 2 is incorrect. Viruses cannot be cultured in synthetic or non-living media. Their replication is entirely dependent on the living cells of a host organism, as they utilize the host's cellular machinery for all their metabolic and reproductive activities.
• Statement 3 is incorrect. Viruses can be transmitted through various means, not solely by biological vectors. While biological vectors (e.g., mosquitoes, ticks) play a crucial role in the life cycle and transmission of many viruses, mechanical vectors (e.g., contaminated surfaces, surgical instruments, or insects that passively carry the virus) also facilitate transmission. Additionally, direct contact, airborne droplets, and contaminated food/water are other modes of viral transmission.