Virology Questions and Answers - Structure of Viruses

1.Cell lines are the type of cell culture.
a) True
b) False

Answer: a
Explanation: There are usually three types of cell cultures: primary cells, cell lines and permanent cell lines. Primary cells are derived from organs and remain differentiated whereas cell lines are dedifferentiated and survive a larger number or maybe immortal.

2. Which of the following PCR is used for the conversion of RNA to DNA?
a) Q-PCR
b) RT-PCR
c) Nested PCR
d) Multiplex PCR

Answer: b
Explanation: RT-PCR or reverse transcriptase PCR is used for the conversion of RNA to cDNA using reverse transcriptase enzyme and then amplify the specific sequence or regions of DNA. It is also called as RT-qPCR.

3. Viruses, outside their host cells, survive as ____________
a) bacteria
b) virions
c) algae
d) protozoa

Answer: b
Explanation: The viruses outside their host cells survive as virus particles, which is also known as virions. The virion contains the viral genome and is a gene delivery system.

4. The viral genome is packaged into a structure made of ______________
a) protein
b) carbohydrate
c) fats
d) lipids

Answer: a
Explanation: The viral genome is packaged into a structure made up of protein. This outer protein structure is known as a capsid. Its main function is to protect the viral nucleic acid from digestion by enzymes.

5. Which of the following is not the category of virus genome?
a) dsDNA
b) ssRNA
c) tsDNA
d) dsRNA

Answer: c
Explanation: All the nucleic acids exist as double-stranded (ds) or single-stranded (ss). Thus, it gives four categories of virus genome: dsDNA, ssDNA, dsRNA, ssRNA.

6. Most of the plant viruses have ____________
a) ssRNA
b) ssDNA
c) dsDNA
d) dsRNA

Answer: a
Explanation: The majority of the plant viruses have single-stranded RNA as their genome, while most of the fungal viruses have double-stranded RNA and most prokaryotic viruses have double-stranded DNA genomes.

7. Which of the following organism contains the largest genome size?
a) HBV
b) Phage lambda
c) Mimivirus
d) Mycoplasma genetalium

Answer: c
Explanation: Mimivirus possesses the largest genomic size of about 1200 kilobase pairs of DNA. The phage lambda possesses 48.5 kbp, HBV possesses 3.2 kbp and Mycoplasma genetalium possesses 580 kbp DNA.

8. Which of the following virus possess a single-stranded, linear genome?
a) TMV
b) Poxvirus
c) Baculovirus
d) Reovirus

Answer: a
Explanation: The tobacco mosaic virus (TMV) possesses a single-stranded, linear RNA genome. Whereas poxvirus possesses double-stranded, linear genome, baculovirus possesses double-stranded, circular genome and reovirus has a double-stranded, linear genome.

9. Which of the following is the most common capsid shape of the virus?
a) Cube
b) Rod
c) Cone
d) Icosahedron

Answer: d
Explanation: The most common capsid shape of the virus is icosahedron and helical symmetries. Some of the examples of symmetrical structures are rod, helix, cone, and icosahedron. An icosahedron is an object or symmetry with 20 faces, 12 vertices, and 30 edges.

10.The number of subunits in a virus particle is given by _________
a) T = Pf
b) P = Tf
c) T = Pf2
d) T = Pf3

Answer: c
Explanation: The number of subunits in a virus particle is given by T = Pf2, where T is the triangulation number. P is given by the expression h2 + hk + k2. In this expression, h and k are any pair of integers without common factors, i.e. h and k cannot be multiplied or divided by any number to give the same values, f = 1, 2, 3, 4, etc.