By which route would an HIV infection not be transmissible?
A) blood
B) saliva
C) sharing needles for injections
D) semen
▶️ Answer/Explanation
Ans: B
HIV is transmitted through bodily fluids containing high viral loads, such as blood (A), semen (D), and vaginal fluids, as well as via shared needles (C). However, saliva (B) does not contain sufficient HIV particles to cause infection under normal circumstances, making it a non-transmissible route. Therefore, the correct answer is B (saliva).
The table shows the number of new HIV infections in 1990 and 2021 in one country.
Which statement could explain the change in the number of new HIV infections between 1990 and 2021?
A) Condoms, which prevent the transmission of STIs, increased in price between 1990 and 2021.
B) People in 2021 had more sexual partners.
C) Testing of donated blood for pathogens was introduced in 1990.
D) There was an increase in drug abuse between 1990 and 2021.
▶️ Answer/Explanation
Ans: C
The table shows a decrease in new HIV infections from 1990 to 2021. The most plausible explanation is C (Testing of donated blood for pathogens was introduced in 1990), as this would reduce transmission via blood transfusions.
Why not others?
– A: Higher condom prices would likely increase infections, not decrease them.
– B: More sexual partners would also likely increase transmission.
– D: Increased drug abuse (often involving shared needles) would raise HIV rates, not lower them.
Thus, C is the only option that aligns with the observed decline in infections.