Disease Prevention & Substance Abuse — NEET Biology
📚 Practice ConceptAmong other diseases, AIDS and cancer kill a large number of individuals worldwide. AIDS caused by the human immuno-deficiency virus (HIV) is fatal but can be prevented if certain precautions are taken. Many cancers are curable if detected early and appropriate therapeutic measures are taken. Of late, drug and alcohol abuse among youth and adolescents is becoming another cause of concern. Because of the addictive nature of alcohol and drugs, and their perceived benefits like relief from stress, a person may try taking these in the face of peer pressure, examinations-related and competition-related stresses. In doing so, he/she may get addicted to them. Education about their harmful effects, counselling and seeking immediate professional and medical help would totally relieve the individual from these evils.
Which of the following statements about retroviruses, specifically HIV, are correct? S1: Retroviruses possess a DNA genome that directly integrates into the host's nuclear DNA. S2: The enzyme reverse transcriptase is unique to retroviruses and is crucial for their replication cycle. S3: All retroviruses primarily infect helper T-lymphocytes, causing immunodeficiency. S4: The replication of HIV involves the formation of viral particles by the host cell's machinery after viral DNA integration. S5: Retroviruses like HIV are characterized by having an envelope around their genetic material.
View solution & NCERT explanation
Correct answer: C — S2, S4 and S5 only
The core concept tested here is the characteristic features of retroviruses, using HIV as a prime example, based on NCERT descriptions. S1: This statement is incorrect. Retroviruses, including HIV, possess an RNA genome, not a DNA genome. This RNA genome is reverse transcribed into DNA before integration into the host's DNA. S2: This statement is correct. Reverse transcriptase is an enzyme that synthesizes DNA from an RNA template, a process 'reverse' to conventional transcription. It is a defining feature of retroviruses and essential for their life cycle. S3: This statement is incorrect. While HIV primarily infects helper T-lymphocytes and causes immunodeficiency, the statement 'All retroviruses primarily infect helper T-lymphocytes' is an overgeneralization. There are other retroviruses that infect different cell types or cause other diseases. S4: This statement is correct. After the viral DNA integrates into the host's DNA, it directs the host cell's machinery to produce new virus particles, including viral proteins. S5: This statement is correct. Retroviruses, including HIV, are enveloped viruses, meaning their genetic material (RNA genome) is enclosed within an envelope. Therefore, statements S2, S4, and S5 are correct. This question assesses detailed knowledge of retroviral structure, enzymes, and replication, specifically in the context of HIV.
What does NCERT say about Among other diseases AIDS?
Has this concept appeared in NEET?
Which chapter is this from?
Through deep analysis of NEET and NTA, 176 of the 180 ReNEET 2026 (June 21) questions were already in the MedicNEET question bank before the exam.
176/180MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.