BSL 113_CAT 1_2023

SOKOINE UNIVERSITY OF AGRICULTURE
College of Veterinary Medicine and Biomedical Sciences

BLS 113: Virology CAT 1 Total Marks: 61 Date: 05th May 2023 Time: 30 minutes

1. Select the best answer among the alternative statements given for each question and circle it (15 marks)
i. A chemical component that is found in all viruses is:
A) Protein B) Lipid C) DNA D) RNA E) Carbohydrate

ii. A structural component that is found in all viruses is:
A) The envelope B) DNA C) Capsid D) Tail fibers E) Matrix core

iii. Which of the following is not true of virions?
A) Reproduce independently B) Contain DNA C) Contain RNA D) Are extracellular

iv. A common polyhedral capsid shape of viruses is a:
A) Pentagon B) Cube C) Icosahedron D) Pyramid E) Sphere

v. The viral nucleocapsid is the combination of
A) genome and capsid B) capsid and spikes C) envelope and capsid D) capsomere and genome

vi. In the simplest capsid, there is a capsomere at each of the 12 vertices; this capsomere, which is surrounded by five other capsomeres, is termed a
A) penton B) polyhedral C) icosahedral D) helical

vii. Poxviruses replicate:
A) On a plasmid B) In the cytoplasm C) Nucleus D) Within the nucleus

viii. Replication of RNA viruses typically occurs in the:
A) Nucleus B) Golgi C) Endoplasmic reticulum D) Cytoplasm

ix. Which of the following internalization method is mostly used by enveloped viruses to enter a cell:
A) fusion B) viropexis C) integration D) pore formation

x. Which viruses always have an RNA genome that acts as a template for DNA synthesis?
A) reoviruses B) retroviruses C) hepadnaviruses D) influenza A virus

xi. Viruses largely lack metabolic machinery of their own to generate energy or to synthesize….
A) protein B) carbohydrate C) capsid D) nucleic acids

xii. When a virus enters a cell but does not replicate immediately, the situation is called
A) lysogeny B) latent C) symbiosis D) synergism E) incubation F) lytic

xiii. The first step in infection of a host cells by a virus is called
A) adsorption B) absorption C) abruption D) penetration E) replication F) fusion

xiv. In the one-step growth curve, the time from infection until lysis is known as
A) eclipse period B) rise period C) latent period D) burst size

xv. All negative sense RNA viruses have:
A) no envelope B) envelope C) segmented genomes only D) non-segmented genomes only
E) no RNA-dependent RNA polymerase

 

2. Match list A with the correct answer in list B, then write the letter from list B in spaces provided in list A (10 marks)

LIST A

LIST B

i.      Named based on how they were originally thought to be contracted……….. ii.    Tobacco mosaic virus, Ebora virus, influenza, measles and rabies virus are examples of viruses with ……………….. capsid symmetry iii.  Viruses originated from cellular (RNA and DNA) genetic material that has acquired the capacity to exist and function independently……………………… iv.   Example of a virus with the nature of the symmetry not fully understood giving an appearance of untidy ball of wool………………………………………. v.     A form of a virus when outside the cell…………………………………….. vi.   The mechanism used by most of the non-enveloped viruses to leave the cell after replication……………………………………………………………… vii.  The enzyme that MUST be packaged by -ssRNA viruses within their virion for replication and transcription…………………………………… viii.  Viral proteins such as enzymes or transcription factors for virus replication which are not incorporated in the virus are called…………………………………… ix.    A cell with the capacity to replicate the virus is called……………………… x.       The integrated retroviral DNA genome is called……………………………

A.   Regressive theory B.    Icosahedral C.    Poxvirus D.   Dengue virus E.    Progressive theory F.    Helical G.   Permissive H.   RdDp I.      Provirus J.     Non-structural proteins K.   Lysis L.    Susceptible M.  Core N.   Proviral RNA O.   Prion P.    RdRp Q.   Virion R.    Budding

 

3. Write down the name of virus group based on Baltimore classification, the sites for virus genome replication and transcription takes place and state whether the virus group packages any enzyme within the virion or not (36 marks).

Baltimore Class	Virus group	Site for genome replication	Site for transcription	Package enzyme (s) or not
Class I (smaller)
Class I (larger)
Class II
Class II
Class IV
Class V (segmented)
Class V (non-segmented)
Class VI
Class VII

 

 

*********************************************BEST WISHES****************************************************************