Viruses

 

Here are 11 Multiple Choice Questions (MCQs) on viruses:

Question 1: Which of the following is NOT a characteristic of viruses?

a) They can replicate outside host cells

b) They contain either DNA or RNA

c) They are obligate intracellular parasites

d) They can have a protein coat called a capsid 

Correct Answer: a) They can replicate outside host cells

Explanation: Viruses cannot replicate outside of living cells; they require a host cell's machinery to reproduce.

Question 2: What term describes the protein shell that encloses the genetic material of a virus?

a) Envelope

b) Capsid

c) Nucleocapsid

d) Matrix 

Correct Answer: b) Capsid

Explanation: The capsid is the protein shell or coat that encloses the viral nucleic acid.

Question 3: Which virus has a single-stranded RNA genome and causes the common cold?

a) Influenza virus

b) Rhinovirus

c) Rotavirus

d) Parvovirus 

Correct Answer: b) Rhinovirus

Explanation: Rhinoviruses are one of the primary causes of the common cold, characterized by their single-stranded RNA genome.

Question 4: The process by which a virus integrates its DNA into the host's DNA is known as:

a) Lysis

b) Conjugation

c) Lysogeny

d) Budding 

Correct Answer: c) Lysogeny

Explanation: Lysogeny refers to the integration of viral DNA into the host's chromosome, where the virus remains dormant as a prophage.

Question 5: Which of these viruses is known for its reverse transcriptase enzyme?

a) Hepatitis B virus

b) Herpes simplex virus

c) Smallpox virus

d) Poliovirus 

Correct Answer: a) Hepatitis B virus

Explanation: Hepatitis B virus, like retroviruses, uses reverse transcriptase to convert its RNA genome into DNA before integration into the host genome.

Question 6: What type of vaccine involves using a weakened or attenuated form of the virus?

a) Inactivated vaccine

b) Subunit vaccine

c) Live attenuated vaccine

d) DNA vaccine 

Correct Answer: c) Live attenuated vaccine

Explanation: Live attenuated vaccines contain a weakened form of the virus that can still replicate but causes a mild or no disease, stimulating a strong immune response.

Question 7: The virus that causes AIDS is:

a) Human Papillomavirus (HPV)

b) Human Immunodeficiency Virus (HIV)

c) Hepatitis C Virus (HCV)

d) Herpes Simplex Virus (HSV) 

Correct Answer: b) Human Immunodeficiency Virus (HIV)

Explanation: HIV is the virus responsible for Acquired Immune Deficiency Syndrome (AIDS).

Question 8: Which of the following viral diseases is transmitted primarily through the respiratory route?

a) Hepatitis A

b) Dengue

c) Influenza

d) Yellow Fever 

Correct Answer: c) Influenza

Explanation: Influenza virus is mainly spread through respiratory droplets when an infected person coughs or sneezes.

Question 9: What is the term for the viral cycle where the virus immediately replicates and lyses the host cell?

a) Latent phase

b) Lytic cycle

c) Lysogenic cycle

d) Persistent infection 

Correct Answer: b) Lytic cycle

Explanation: In the lytic cycle, the virus replicates within the host cell, leading to the eventual lysis of the cell and release of new virions.

Question 10: Which virus is known for its icosahedral symmetry and causes warts?

a) Adenovirus

b) Papillomavirus

c) Paramyxovirus

d) Enterovirus 

Correct Answer: b) Papillomavirus

Explanation: Human Papillomavirus (HPV) has icosahedral symmetry and is the cause of warts and other conditions, including some cancers.

Question 11: Which of the following is a strategy viruses use to evade the host immune system?

a) Rapid mutation

b) Production of antibiotics

c) Formation of biofilms

d) Photosynthesis 

Correct Answer: a) Rapid mutation

Explanation: Viruses like influenza or HIV can mutate rapidly, which allows them to evade the host's immune response by changing their antigenic structures.