AIDS (Acquired Immuno Deficiency Syndrome) is caused by HIV (Human Immuno deficiency Virus), which is an enveloped retrovirus with two identical single-stranded RNA molecules and two molecules of reverse transcriptase. HIV spreads through sexual contact, sharing infected injection needles, blood transfusion, and from an infected mother to the foetus. Memory hook: HIV = "Retro-virus, RNA, Reverse transcriptase" — all start with R, and it Reduces your helper T-cells.
HIV is an enveloped retrovirus (2 single-stranded RNA + 2 reverse transcriptase) that causes AIDS. It spreads by four routes: sexual contact, shared infected needles, transfusion of infected blood, and from an infected mother to the foetus.
Your doubts, answered
Is AIDS caused by a virus or a bacterium?
AIDS is caused by a VIRUS, not a bacterium. The virus is HIV (Human Immuno deficiency Virus). Because it is viral, AIDS is NOT completely curable — this is a very common NEET trap. Bacterial STIs like gonorrhoea (Neisseria) and syphilis (Treponema) are curable if treated early, but HIV, genital herpes and hepatitis-B are not.
Why is HIV called a retrovirus?
HIV is a retrovirus because it carries its genetic material as RNA and uses the enzyme reverse transcriptase to make DNA from that RNA inside the host cell (the reverse of the normal DNA to RNA flow). HIV is enveloped and diploid — it holds two identical single-stranded RNA molecules and two molecules of reverse transcriptase. NEET repeatedly tests these exact numbers: two RNA + two reverse transcriptase.
How does HIV spread from one person to another?
NCERT lists four routes: (1) sexual contact with an infected person, (2) sharing infected injection needles or surgical instruments, (3) transfusion of infected blood, and (4) from an infected mother to her foetus (through the placenta). HIV does NOT spread by touching, sharing food, or mosquito bites — remember only the four blood/fluid routes for NEET.
Does HIV have DNA or RNA?
HIV has RNA as its genetic material — specifically two identical single-stranded RNA molecules. It converts this RNA into DNA using reverse transcriptase after entering the host cell. So the virus particle carries RNA, but it makes DNA inside you. This is why option 'HIV contains one molecule of RNA' is wrong in NEET 2016.
What is the difference between HIV and AIDS?
HIV is the virus (the cause); AIDS is the disease (the effect). HIV infects and destroys helper T-lymphocytes (T-H cells), replicates inside them, and slowly weakens the immune system. When immunity drops badly, the condition is called AIDS. So you can be HIV-positive before you develop full AIDS.
⚠️ The NEET trap ✗ HIV is an unenveloped retrovirus with one molecule of single-stranded RNA and one molecule of reverse transcriptase. ✓ HIV is an ENVELOPED retrovirus with TWO identical single-stranded RNA molecules and TWO molecules of reverse transcriptase. 🧠 NEET 2016 tested exactly this. Two things to lock: HIV is enveloped (not naked), and it is diploid — remember 'two and two' (2 RNA, 2 reverse transcriptase).
Real NEET questions
2016
Which of the following is correct regarding AIDS causative agent HIV?
A · HIV is enveloped virus containing one molecule of single-stranded RNA and one molecule of reverse transcriptase
B · HIV is enveloped virus that contains two identical molecules of single-stranded RNA and two molecules of reverse transcriptase ✓
C · HIV is unenveloped retrovirus
D · HIV does not escape but attacks the acquired immune response
Solution: HIV is an enveloped retrovirus carrying two identical single-stranded RNA molecules and two molecules of reverse transcriptase, so B is correct. A understates the count, C is wrong because HIV is enveloped, and D is wrong because HIV does evade the immune system and destroys helper T-cells.
2017
Match the sexually transmitted diseases (Column I) with their causative agent (Column II): (a) Gonorrhea (b) Syphilis (c) Genital Warts (d) AIDS; (i) HIV (ii) Neisseria (iii) Treponema (iv) Human Papilloma virus.
A · (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i) ✓
B · (a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)
C · (a)-(iv), (b)-(ii), (c)-(iii), (d)-(i)
D · (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)
Solution: Gonorrhoea is caused by Neisseria, syphilis by Treponema, genital warts by Human Papilloma virus, and AIDS by HIV. This gives (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i) = option A. All other combinations misassign at least one agent.
Solved Reproductive Health NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
AIDS is caused by HIV (Human Immuno deficiency Virus), an enveloped retrovirus that carries two RNA molecules and two molecules of reverse transcriptase.
Is AIDS curable?
No. AIDS is not completely curable because it is a viral infection. NCERT states that except for hepatitis-B, genital herpes and HIV, the other STIs are curable if treated early.
Which cells does HIV attack?
HIV enters and replicates inside helper T-lymphocytes (T-H cells), producing progeny viruses that destroy more helper T-cells, causing immunodeficiency.
Does HIV specifically affect the reproductive organs?
No. Along with hepatitis-B, HIV/AIDS is an STI that does NOT specifically affect the reproductive organs — it is a systemic infection that attacks the immune system.
How can HIV transmission be prevented?
Avoid unprotected sex, use disposable needles and sterile instruments, screen blood before transfusion, and screen infected mothers to prevent mother-to-foetus spread.
