301. Which group is considered at higher risk for HIV infection because of direct blood exposure through shared equipment?
ⓐ. Intravenous drug abusers sharing needles
ⓑ. Students sharing notebooks in a classroom
ⓒ. Players using the same sports ground
ⓓ. Family members eating at the same table
Correct Answer: Intravenous drug abusers sharing needles
Explanation: Shared needles can transfer infected blood directly from one person to another. That makes intravenous drug abuse a major risk factor for HIV transmission. Ordinary contact through shared objects like books or furniture does not provide this blood-borne route. The presence of direct blood exposure is the key factor here.
302. Which of the following is not regarded as a common high-risk situation for HIV transmission?
ⓐ. Receiving screened blood from a safe source
ⓑ. Having multiple sexual partners
ⓒ. Sharing infected needles
ⓓ. Birth from an infected mother
Correct Answer: Receiving screened blood from a safe source
Explanation: Screened blood from a safe source is used specifically to reduce the chance of HIV transmission. Multiple sexual partners, shared infected needles, and mother-to-child transfer are all recognized risk situations. The difference lies in whether exposure to infected body fluids is likely. Safe screening lowers that risk greatly.
303. A person repeatedly receives blood transfusions from unscreened sources. The main concern is increased risk of
ⓐ. common cold
ⓑ. HIV infection
ⓒ. ringworm
ⓓ. filariasis
Correct Answer: HIV infection
Explanation: HIV can spread through contaminated blood and blood products. Repeated transfusions from unscreened sources increase the chance that infected blood may enter the body. This route is very different from droplet-borne, skin fungal, or mosquito-borne diseases. Blood safety is therefore a major preventive step.
304. Which statement best explains why people with multiple sexual partners are placed in a higher-risk group for HIV?
ⓐ. They are always born with weaker immunity.
ⓑ. They are more likely to face exposure through infected body fluids.
ⓒ. They naturally lose antibodies faster than others.
ⓓ. They cannot develop acquired immunity.
Correct Answer: They are more likely to face exposure through infected body fluids.
Explanation: HIV transmission depends on specific routes involving infected body fluids. Increasing the number of sexual partners can increase the probability of exposure to an infected person. This does not mean immunity is absent, but that the chance of encountering the virus becomes greater. The risk is therefore behavioral and exposure-based.
305. Which pair includes only groups recognized as being at higher risk of HIV infection?
ⓐ. Intravenous drug abusers and repeated transfusion recipients
ⓑ. Schoolchildren sitting in the same classroom and bus passengers
ⓒ. Players in the same team and neighbours in the same building
ⓓ. Office workers using the same staircase and library users
Correct Answer: Intravenous drug abusers and repeated transfusion recipients
Explanation: Higher-risk groups are identified by likelihood of exposure to infected blood or other relevant body fluids. Intravenous drug abusers sharing needles and people receiving repeated unscreened transfusions fit this criterion. Casual proximity in schools, buses, offices, or libraries does not create the same transmission route. Risk depends on route, not on ordinary physical nearness.
306. HIV may be transmitted from mother to child mainly through
ⓐ. mosquito bites soon after birth
ⓑ. casual touch during infancy
ⓒ. the placenta during pregnancy
ⓓ. dust particles in the room
Correct Answer: the placenta during pregnancy
Explanation: Mother-to-child transmission is a recognized route of HIV spread. One important pathway is placental transfer during pregnancy, allowing the virus to reach the developing baby. This is why prenatal screening and medical care are important in prevention. Casual touch and insect bites do not explain this route.
307. Which of the following does not spread HIV in normal daily life?
ⓐ. Using an infected syringe
ⓑ. Casual handshaking
ⓒ. Receiving contaminated blood
ⓓ. Sexual contact with an infected person
Correct Answer: Casual handshaking
Explanation: HIV is not transmitted through casual physical contact such as handshaking. Its spread requires specific routes involving infected blood or certain body fluids. This distinction is important because it prevents unnecessary fear and social isolation of infected individuals. Everyday touch is not a normal transmission route.
308. A student refuses to sit beside a classmate living with HIV because he fears infection from sharing the same bench. This fear is
ⓐ. justified because HIV spreads through clothes and benches
ⓑ. justified because HIV spreads through sweat in classrooms
ⓒ. justified because HIV spreads through air in closed rooms
ⓓ. unjustified because casual contact does not transmit HIV
Correct Answer: unjustified because casual contact does not transmit HIV
Explanation: HIV does not spread by sitting near someone, sharing benches, or ordinary classroom contact. The virus requires specific transmission routes such as infected blood, sexual contact, shared needles, or mother-to-child transfer. Misunderstanding these facts leads to stigma rather than real protection. Correct knowledge is therefore important for both health and social behavior.
309. Which comparison between HIV transmission and common cold transmission is correct?
ⓐ. HIV and common cold are both spread mainly by sneezing droplets.
ⓑ. HIV spreads through specific body-fluid routes, whereas common cold spreads easily through droplets and contaminated objects.
ⓒ. HIV spreads through mosquito bites, whereas common cold spreads through blood transfusion.
ⓓ. HIV and common cold are both commonly spread by casual touch.
Correct Answer: HIV spreads through specific body-fluid routes, whereas common cold spreads easily through droplets and contaminated objects.
Explanation: Common cold is a droplet-borne upper respiratory infection that also spreads through contaminated objects. HIV does not spread in that casual respiratory way and instead requires specific body-fluid exposure. This difference explains why prevention methods for the two diseases are very different. Route of transmission is the main basis of comparison here.
310. Assertion (A): HIV is not spread by ordinary social contact.
Reason (R): The virus requires specific transmission routes such as infected blood, sexual contact, shared needles, or mother-to-child transfer.
ⓐ. Both A and R are true, and R is the correct explanation of A.
ⓑ. Both A and R are true, but R is not the correct explanation of A.
ⓒ. A is true, but R is false.
ⓓ. A is false, but R is true.
Correct Answer: Both A and R are true, and R is the correct explanation of A.
Explanation: HIV transmission is route-specific rather than casual. Since the virus spreads through particular body-fluid exposures, ordinary social contact does not normally transmit it. The reason directly explains why handshakes, shared seating, and casual proximity are not major risks. This is a key fact in reducing stigma.
311. Which person is most clearly placed in a recognized higher-risk group for HIV exposure?
ⓐ. A child playing in a public park
ⓑ. A teacher correcting notebooks in class
ⓒ. A patient repeatedly receiving unscreened blood transfusions
ⓓ. A traveller sharing a waiting room with others
Correct Answer: A patient repeatedly receiving unscreened blood transfusions
Explanation: Unscreened blood transfusions may introduce infected blood directly into the bloodstream. That makes repeated transfusion recipients a recognized higher-risk group when blood safety is not ensured. The other situations involve ordinary daily contact without the required transmission route. Blood exposure is the key issue here.
312. Fill in the blank in the most accurate way:
HIV does not spread by touch or casual contact, but it can spread through infected blood, sexual contact, shared needles, and from infected mother to child through the ______.
ⓐ. alveoli
ⓑ. intestine
ⓒ. skin surface
ⓓ. placenta
Correct Answer: placenta
Explanation: One recognized route of HIV transmission is from an infected mother to her child during pregnancy. The placenta provides the pathway for this maternal transmission. This is quite different from casual touch, which does not spread the virus. The fill-in highlights the specific, medically important route.
313. Which cell is commonly infected first by HIV after it enters the human body?
ⓐ. Erythrocyte
ⓑ. Macrophage
ⓒ. Mast cell
ⓓ. Neutrophil
Correct Answer: Macrophage
Explanation: HIV can enter macrophages soon after infection. These cells are important because they can harbour the virus and support its multiplication. Their infection helps the virus establish itself in the body before immune damage becomes more obvious. Macrophages therefore play an early role in HIV infection.
314. Which enzyme enables HIV to form DNA from its RNA inside the host cell?
ⓐ. DNA ligase
ⓑ. Helicase
ⓒ. RNA polymerase
ⓓ. Reverse transcriptase
Correct Answer: Reverse transcriptase
Explanation: HIV is a retrovirus, so it carries RNA as its genetic material. To continue its life cycle in the host, it must first produce a DNA copy from that RNA. Reverse transcriptase performs this unusual step. This feature is one of the defining properties of retroviruses.
315. Which sequence correctly describes an important early molecular step in HIV infection?
ⓐ. Viral RNA → viral DNA
ⓑ. Viral DNA → viral RNA
ⓒ. Host protein → viral lipid
ⓓ. Antibody → viral enzyme
Correct Answer: Viral RNA → viral DNA
Explanation: HIV enters the host cell with an RNA genome, but it does not remain only in RNA form during replication. Using reverse transcriptase, it produces a DNA copy. This DNA can then become associated with the host genetic material. The RNA-to-DNA step is central to HIV biology.
316. After reverse transcription, the newly formed viral DNA becomes
ⓐ. dissolved in plasma
ⓑ. stored in erythrocytes
ⓒ. integrated into host DNA
ⓓ. converted into antibody
Correct Answer: integrated into host DNA
Explanation: Once viral DNA is formed, it can become part of the host cell’s genetic material. This integration allows the host cell machinery to be used for production of new viral components. It also helps the virus persist inside the body. Integration is therefore a key step in long-term infection.
317. Why are macrophages often described as virus-producing cells in HIV infection?
ⓐ. They convert antibodies directly into viruses.
ⓑ. They destroy all viral particles immediately.
ⓒ. They stop reverse transcription completely.
ⓓ. They can support repeated production of new HIV particles.
Correct Answer: They can support repeated production of new HIV particles.
Explanation: After HIV infects macrophages and its DNA integrates into the host genome, these cells can continue producing new viruses. In that sense, they act like virus-producing cells. This helps spread infection within the body over time. Their role is therefore more than simple uptake of the virus.
318. Which lymphocyte population is progressively reduced in HIV infection, leading to weakening of immunity?
ⓐ. B-lymphocytes
ⓑ. Helper T-lymphocytes
ⓒ. Platelets
ⓓ. Erythrocytes
Correct Answer: Helper T-lymphocytes
Explanation: Helper T-lymphocytes are major targets in HIV infection. Their gradual decline weakens the coordination of immune responses, because these cells are important in activating and regulating other immune components. As their number falls, the body becomes less able to defend itself effectively. This progressive loss is central to the development of AIDS.
319. Which statement best explains why HIV causes severe immune deficiency?
ⓐ. It damages key immune cells involved in regulation and defense.
ⓑ. It blocks all digestion in the small intestine.
ⓒ. It affects only skin cells and hair follicles.
ⓓ. It remains confined to alveoli of the lungs.
Correct Answer: It damages key immune cells involved in regulation and defense.
Explanation: HIV does not mainly act by disturbing digestion or by staying limited to one surface tissue. Its major effect is on crucial immune cells, especially helper T cells and macrophages. Because these cells are important in organizing defense, their damage weakens the whole immune system. The result is progressive immune deficiency.
320. Which option best describes the role of reverse transcriptase in HIV infection?
ⓐ. It produces antibodies against HIV.
ⓑ. It breaks down host DNA completely.
ⓒ. It synthesizes DNA using viral RNA as template.
ⓓ. It converts viral proteins into lipids.
Correct Answer: It synthesizes DNA using viral RNA as template.
Explanation: Reverse transcriptase carries out a reverse flow of genetic information compared with the usual DNA-to-RNA pattern. In HIV infection, it uses viral RNA as a template to form viral DNA. This step is essential before integration into host DNA can occur. Without it, the virus could not proceed in the same way.
