Question 1

Which enzyme is unique to retroviruses and is responsible for synthesizing double-stranded DNA from single-stranded RNA?

Accepted Answer

Reverse transcriptase (RT)

Question 2

HIV can only infect host cells that express which specific receptor and co-receptor combination?

Accepted Answer

CD4 receptor and CCR5 or CXCR4 co-receptor

Question 3

Which of the following best describes the integration of retroviral genes into the host genome?

Accepted Answer

Retroviral DNA is permanently integrated into host DNA

Question 4

What is the primary cause of Acquired Immunodeficiency Syndrome (AIDS)?

Accepted Answer

Infection with a single-stranded RNA retrovirus (HIV)

Question 5

Which of the following is NOT a common route of HIV transmission?

Accepted Answer

Casual contact such as hugging

Question 6

Why does HIV not survive long outside the human body?

Accepted Answer

It requires host cell machinery for replication

Question 7

Which protein on the HIV envelope is responsible for docking to the CD4 receptor on host cells?

Accepted Answer

GP-120

Question 8

A mutation in which co-receptor can provide natural resistance to HIV infection?

Accepted Answer

CCR5

Question 9

Which of the following equations best represents the action of reverse transcriptase in HIV?

Accepted Answer

$RNA \rightarrow DNA$

Question 10

Which population group accounted for the majority of new HIV infections in the United States in 2020?

Accepted Answer

Males with male-to-male sexual contact

Question 11

What is the role of the integrase enzyme in the HIV life cycle?

Accepted Answer

Integrates viral DNA into host genome

Question 12

Which step in the HIV multiplication cycle allows the virus to become a permanent part of the host cell's genetic material?

Accepted Answer

Integration of viral DNA into host genome

Question 13

A newborn is diagnosed with HIV. Which of the following is the most likely route of transmission?

Accepted Answer

Either breastfeeding or transplacental transmission

Question 14

Which of the following statements about antiretroviral therapy (ART) is correct?

Accepted Answer

ART slows progression of HIV disease

Question 15

Which of the following is a plausible reason why donated blood rarely transmits HIV today?

Accepted Answer

Rigorous screening and testing of blood products

Question 16

Which of the following best explains why HIV infection leads to immunodeficiency?

Accepted Answer

HIV destroys CD4+ T cells, impairing immune response

Question 17

A patient is found to have a mutation in the CCR5 gene. What is the most likely consequence?

Accepted Answer

Natural resistance to HIV infection

Question 18

Which of the following is a multi-step process that occurs during HIV infection?

Accepted Answer

Binding to CD4 receptor, fusion, reverse transcription, integration

Question 19

Which of the following best describes the epidemiology of HIV in the United States?

Accepted Answer

Most new infections occur in males, often through male-to-male sexual contact

Question 20

Which of the following is a correct sequence of events in the HIV multiplication cycle?

Accepted Answer

Attachment, fusion, reverse transcription, integration, assembly, release

Chapter 25: RNA Viruses that Infect Humans – Human Retroviruses and HIV

Study Guide - Practice Questions