Biology · General Awareness

Viral Diseases and Immunity

807 Questions

Viral diseases and immunity cover the structure, transmission, and diagnosis of viruses like HIV. Questions focus on disease pathways, immune responses, and prevention. Strong knowledge here provides an edge in biology scoring.

HIV and AIDS structureVirus transmission methodsImmune system deficiencyPathogen risk groupsMedical diagnosis methods

Viral Diseases and Immunity Questions

Multiple choice

Which of the following statements does not characterise viruses?

  1. The morphology of a virus is determined by the number of the protomeres.

  2. Viral nucleic acid is enclosed in a capsid made up of protein subunits called protomeres.

  3. All viruses undergo a replication cycle in their human host cell.

  4. During the viral replication cycle, an accumulation of mature viruses, incomplete viruses and viral parts occurs within the cell.

  5. A virally-infected cell generally presents three signals that it is infected.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The morphology of a virus is determined by the arrangement of the protomeres. When protomeres aggregate into units of five or six (capsomeres) and then condense to form a geometric figure having 20 equal triangular faces and 12 apices, the virus is said to have icosahedral (cubic) morphology. When protomeres aggregate to form a capped tube, they are said to have helical morphology. Any other arrangement of the protomeres results in a complex morphology.

Multiple choice

Viroids are well known plant pathogens. Which of the following statements does not characterise viroids?

  1. Viroid RNA does not code for any protein.

  2. Viroid causes hepatitis D in humans.

  3. Viroids are infectious agents composed solely of circular single-stranded DNA.

  4. The viroid siRNAs contains sequences capable of complementary base pairing with the plant's mRNAs.

  5. Some viroids are ribozymes also.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Viroids are infectious agents composed solely of circular single-stranded RNA which folds over on itself to form some double stranded regions. These are catalytic RNAs (ribozymes).

Multiple choice

The doughnut shaped virus is

  1. cytomegalovirus

  2. calicivirus

  3. astrovirus

  4. norwalk virus

  5. torovirus
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

These virus are pathogens for both humans and animals. They are pleiomorphic, coated, single positive strand RNA viruses. In the electron microscope, they have a doughnut shape.

Multiple choice

Which of the following viral proteins controls the nuclear import of the HIV-1 pre-integration complex in the host cell?

  1. Tat

  2. Rev

  3. Vpr

  4. Nef

  5. Vif
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Vpr is a Human immunodeficieny viral gene and protein product. Vpr stands for Viral Protein R. It plays an important role in regulating nuclear import of the HIV-1 pre-integration complex and is required for virus replication in non-dividing cells such as macrophages.

Multiple choice

Which of the following viruses is most strongly associated with cancer in aves and mammals?

  1. Cytomegalovirus

  2. Human herpes virus 3

  3. Human herpes virus 5

  4. HHV-8, Kaposi's sarcoma herpes virus

  5. Human herpes virus 4
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

EBV is the herpes virus that is most strongly associated with cancer. It infects primarily lymphocytes and epithelial cells. In lymphocytes, the infection is usually non-productive, while virus is shed (productive infection) from infected epithelial cells.

Multiple choice

Cytomegalovirus (CMV) is a common virus that can infect almost anyone. Which of the following statements does not characterise CMV?

  1. Herpes viruses are DNA viruses.

  2. CMV can down regulate the host response.

  3. CMV is named for the large inclusion bodies in the nucleus of the infected cell.

  4. Primary CMV infection can be mild and similar to glandular fever (infectious mononucleosis).

  5. Cytomegalovirus is a member of the retroviral group of viruses.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

CMV is an example of a herpes virus. These are all large DNA viruses of which CMV is the largest and is also known as human herpesvirus-5 (HHV-5).