For UHS MDCAT 2023: Viruses 20 most important repeated mcqs with answers

 

1. What is a virus?

   • Answer: A virus is a submicroscopic infectious agent that cannot grow or reproduce outside a host cell.

2. What is the structure of a virus?

   • Answer: A typical virus consists of genetic material (either DNA or RNA) surrounded by a protein coat called a capsid.

3. What is a bacteriophage?

   • Answer: A bacteriophage is a virus that infects and replicates within bacteria.

4. How do viruses replicate?

   • Answer: Viruses replicate by hijacking the host cell's machinery to produce new viral particles.

5. What is the lytic cycle in viral replication?

   • Answer: The lytic cycle is a viral replication cycle where the virus injects its genetic material into the host cell, takes over the cell's machinery, replicates itself, and then lyses (breaks open) the host cell to release new viral particles.

6. What is the lysogenic cycle in viral replication?

   • Answer: The lysogenic cycle is a viral replication cycle where the virus integrates its genetic material into the host cell's DNA and can remain dormant for an extended period before switching to the lytic cycle.

7. Name a retrovirus and explain its unique feature.

   • Answer: HIV (Human Immunodeficiency Virus) is a retrovirus. Retroviruses have RNA as their genetic material and use reverse transcriptase enzyme to convert RNA into DNA.

8. What is the function of reverse transcriptase?

   • Answer: Reverse transcriptase is an enzyme used by retroviruses to convert their RNA genome into DNA.

9. What is the influenza virus known for, and how does it undergo antigenic drift and shift?

   • Answer: Influenza virus is known for causing seasonal flu. Antigenic drift is a gradual change in the virus's surface proteins, while antigenic shift is a major change resulting from the reassortment of different influenza strains.

10. What is the role of vaccines in preventing viral infections?

    • Answer: Vaccines stimulate the immune system to produce antibodies against specific viruses, providing immunity and protection against infection.

11. What are prions, and what diseases are associated with them?

    • Answer: Prions are misfolded proteins that can cause other proteins to misfold, leading to various neurodegenerative diseases, such as Creutzfeldt-Jakob disease.

12. What is the structure of the coronavirus responsible for COVID-19?

    • Answer: The SARS-CoV-2 virus responsible for COVID-19 has spike proteins on its surface that enable it to attach to and enter human cells.

13. What are the main symptoms of COVID-19?

    • Answer: Common symptoms of COVID-19 include fever, cough, shortness of breath, loss of taste or smell, and fatigue.

14. How can COVID-19 be prevented?

    • Answer: COVID-19 prevention measures include vaccination, wearing masks, practicing good hand hygiene, and maintaining physical distance from others.

15. What is herd immunity, and how is it achieved?

    • Answer: Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, either through vaccination or previous infection, reducing the spread of the disease.

These are general topics related to viruses that are often covered in medical entrance exams. To prepare effectively, it's essential to study your specific course materials and practice with past exam papers and sample questions provided by your institution or exam preparatory resources.