VM 235_CAT 1_2021

SOKOINE UNIVERSITY OF AGRICULTURE

COLLEGE OF VETERINARY MEDICINE AND BIOMEDICAL SCIENCES
DEPARTMENT OF MICROBIOLOGY, PARASITOLOGY AND BIOTECHNOLOGY

VM 235: VETERINARY VIROLOGY CAT 1
TIME ALLOWED: 1 HOUR       DATE: 05-12-2021
Instructions:
1. This paper has TWO printed pages containing THREE questions
2. Answer ALL THREE questions (Total 100 marks)
3. ALL answers to ALL questions MUST be written in the respective spaces provided in each question

1. Briefly, answer the following questions (i-x) in relation to viruses (Total 32.5 marks)

i. Why viruses are referred to as obligate intracellular parasites? (2 marks)
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ii. Why do viruses have smaller size than bacteria (3 marks)
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iii. Mention one structural part found in all viruses? (2 marks)
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iv. Viruses have some of the properties of living organisms. State one characteristic shared by a virus and a living cell (3 marks) …….……………………………………………………….
v. What determines the host range of a virus? (3 marks)
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vi. Why RNA viruses are prone to mutations? (3.5 marks)
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vii. Which group of viruses always have an RNA genome that acts as a template for DNA synthesis? (2 marks) ……………….………………………………………………………….
Why do these viruses synthesize DNA? (3 marks) …..………………………………………..
viii. Why do RNA viruses require their own supply of certain enzymes in their replication cycles? (3 marks)

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ix. The synthesis of viral proteins for all viruses is carried out in the cytoplasm. Why is it so? (3 marks) …………………………………………………………………………………………
x. In the (–) sense RNA genomes, the (+) strands and mRNA are the same. True or False? (2 marks) Why or why not? (3 marks) …………………………………………………………………………………………………..

2. Name the virus groups based on Baltimore classification and the sites where replication of the genome and transcription take place by filling the Table below (Each 1.5 marks, Total 31.5 marks)

3. Provide the name of the enzyme in the table below responsible for viral genome replication and transcription and state whether they are provided by the host or the virus (Total 36 marks)

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