Read the given passage and answer the questions that follow:
The word AIDS means deficiency of immune system acquired during the lifetime of an individual indicating that it is not a congenital disease. AIDS was first reported in 1981 and in the last 25 years it has spread all over the world killing more than 25 million persons. AIDS is caused by the HIV (Human Immuno deficiency Virus). The people who are at high risk of getting this infection include the individuals who have multiple sexual partners, drug addicts who take drugs intravenously, individuals who require repeated blood transfusions and children born to an HIV infected mother. It is imperative for the physical and psychological well-being that the HIV / AIDS infected persons are not isolated from the family and society. A widely used diagnostic test for AIDS is ELISA.
Which one of the following statements about HIV infection and AIDS is incorrect?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → After getting into the body of a person, HIV first enters B-lymphocytes, which continue to produce virus and act like an HIV factory.
The passage says AIDS is caused by HIV and lists the people at high risk, but it does not describe what the virus does inside the body. After HIV enters a person, it first infects macrophages, where its RNA is copied into DNA. It then attacks helper T-lymphocytes, and their number falls steadily, so the body cannot fight even common infections.
Option (1) After getting into the body of a person, HIV first enters B-lymphocytes, which continue to produce virus and act like an HIV factory. — The incorrect statement. HIV first enters macrophages, not B-lymphocytes. The macrophages keep producing virus and act like an HIV factory. The cells HIV then destroys are the helper T-lymphocytes.
Option (2) The time-lag between HIV infection and the appearance of AIDS symptoms may vary from a few months to many years. — A correct statement. There is always a gap between infection and the first symptoms. It may be a few months to many years, usually 5-10 years.
Option (3) Unlike pneumonia or typhoid, HIV infection more often spreads due to conscious behaviour patterns. — A correct statement. Pneumonia and typhoid can be caught without knowing. HIV more often spreads through conscious behaviour, such as unsafe sex or sharing needles, so prevention is the best option.
Option (4) An AIDS patient may suffer from infections due to bacteria especially Mycobacterium, viruses, fungi and even parasites like Toxoplasma. — A correct statement. With fewer helper T-lymphocytes, the patient cannot overcome infections that a healthy body would fight off, from Mycobacterium to Toxoplasma.
NCERT Extract:
AIDS – “… There is always a time-lag between the infection and appearance of AIDS symptoms. This period may vary from a few months to many years (usually 5-10 years). After getting into the body of the person, the virus enters into macrophages where RNA genome of the virus replicates to form viral DNA with the help of the enzyme reverse transcriptase. This viral DNA gets incorporated into host cell’s DNA and directs the infected cells to produce virus particles (Figure 7.6). The macrophages continue to produce virus and in this way acts like a HIV factory. Simultaneously, HIV enters into helper T-lymphocytes (TH), replicates and produce progeny viruses. … Due to decrease in the number of helper T lymphocytes, the person starts suffering from infections that could have been otherwise overcome such as those due to bacteria especially Mycobacterium, viruses, fungi and even parasites like Toxoplasma.”
Prevention of AIDS – “… HIV infection, more often, spreads due to conscious behaviour patterns and is not something that happens inadvertently, like pneumonia or typhoid.”