BLS 113_CAT 1_2022

SOKOINE UNIVERSITY OF AGRICULTURE
College of Veterinary Medicine and Biomedical Sciences

BLS 113: Virology CAT 1 Total Marks: 82 Date: 18th May 2022 Time: 30 minutes

1. Select the best answer among the alternative statements given for each question and circle it (20 marks)

i. Creutzfeldt-Jakob disease (CJD), kuru, scrapie, and Mad Cow disease are caused by:
A) Viroids B) Retroviruses C) DNA viruses D) Prions E) RNA viruses

ii. Which of the following has the largest genome of all human viruses?
A) Poxvirus B) Herpesvirus C) Hepadnavirus D) Adenovirus

iii. A chemical component that is found in all viruses is:
A) Protein B) Lipid C) DNA D) RNA E) Carbohydrate

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

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

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

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

viii. 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

ix. Which of the following is not an RNA virus?
A) Retrovirus B) Enterovirus C) Rhabadovirus D) Adenovirus E) Rubellavirus

x. Viruses that contain two complete copies of positive strand RNA and the enzyme reverse transcriptase are:
A) Toga viruses B) Rhabdoviruses C) Retroviruses D) Reoviruses E) Enteroviruses

2. Match list A with the correct answer in list B, then write the letter from list B in spaces provided in list A (14 marks)

3. The figure below represents a structure of HIV. Answer the questions below based on information on the figure and general knowledge on HIV.a) Name the parts labelled 1-7 (14 marks each)
1.—————————————————–2. —————————————————————
3.—————————————————–4. —————————————————————
5. —————————————————-6. —————————————————————
7. —————————————————

b) Provide ONE function for the following parts of HIV in the figure above (8 marks)
1. ———————————————————————————————————————————
4. ———————————————————————————————————————————
5. ———————————————————————————————————————————
7. ———————————————————————————————————————————
c) Classify the virus based on (8 marks)
(i) Baltimore classification scheme ————————————————————————————–
(ii) Outer covering ———————————————————————————————————-
(iii) Symmetry of the capsid ————————————————————————————————
(iv) Host species the virus infect ——————————————————————————————-
d) To which family do HIV belong? (2 marks) ——————————————————————————
e) What was the criterion used to name the group of viruses where HIV belong? (4 marks)
————————————————————————————————————————————
f) Why is HIV smaller than bacteria? (3 marks) ————————————————————————————————————–
g) What are the three enzymes packaged in the virion of HIV? (6 marks)
i. ——————————————————————————————————————————
ii. ——————————————————————————————————————————
iii. ——————————————————————————————————————————-
4. Provide one main reason as to why we study HIV? (3 marks) ——————————————————————————————-

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