2. The host range of a virus is determined by B) whether its nucleic acid is DNA

Question

2. The host range of a virus is determined by B) whether its nucleic acid is DNA or RNA A) the enzymes carried by the virus D) the proteins on its surface and that of the host C) the proteins in the host's cytoplasm 3. In many ways, the regulation of the genes of a particular group of viruses will be similar to the regulation of the host gme ore, which of the following regulation mechanisms would you expoct of the genes of a bactariophage? ch of the follo of histones A) regulation via acetylation of histones B) positive control mochanisms rather than negative D) relianoe on C) control of more than one gene in an operon transcription activatons 4. Which of the following characteristics is typical of the lytic oycle of a bacteriophage? A) Viral DNA is incorporated into the host genome B) The viral genome replicates without destroying the hos D) The virus-host relationship usually lasts for generations C) A large number of phages are relcased at a time. 5. Which of the following characteristics correctly describes retroviruses? A) They are made up of only a single protein B) They can only reproduce by infecting bacteria. C) They have a single-stranded DNA that acts as a template for DINA syntbesis D) They have a single-stranded RNA that acts as a template for DNA synthesis 6. What is the function of reverse transcriplase in retroviruses? B) It converts host cell RNA into viral DNA A) It uses viral RNA as a template for DNA synthesis C) It translates viral RNA into proteins D) It uses viral RNA as a template for making complementary RNA strands i the Golgi apparatus, which of the 7. If a viral host cell has a mutation that interferes with the addition of carbobydrates to proteins in following processes could likely result? A) The viral envelope proteins would not have glycoproteins added to then and might not arive at the host plasma membrane B) The viral capsid proteins would not have glycoproteins C) The viral core proteins would not have D) The virus would be unable to reproduce within the bost cell. added to them and might not arrive at the host plasma membrane. glycoproteins added to them and might not arrive at the host plasma membrane S. HlV is inactivated in the laboratory after a few minutes of sitting at room temperature, but the flu virus is still active after sitting for several hours. What are the practical consequences of these findings? A)HIV can be transmitted more easily from person to person than the flu virus B) The fnu virus can be transmitted more casily from person to person than HIV C) This property of HIV makes it more likely to be a pandemic than the flu virus D) Disinfecting surfaces is more important to reduce the spread of HIV than the flu 9 Which of the following statements correctly describes vaccines and how they help prevent viral infection? A) Vaccines are active versions of a virus that stimulate an immune reaction in a person. B) Vaccines are inactive versions of a virus that stimulate an immune reaction in a person. C) Vaccines are infectious proteins that stimulate an immune reaction in a person. D) Vaccines are infectious enzymes that stimulate an immune reaction in a person 10. Which of the following statements is correct regarding viral infections in plants? A) They can be controlled with antibiotics C) They have little effect on plant growth. B) They can spread within a plant via plasmodesmata. D) They are not spread by animals II. The difference between vertical and horizontal transmission of plant viruses is that vertical transmission is A) transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to anot B) the spread of viruses from upper leaves to lower leaves of the plant, and horizontal transmission is the spread of a virus amo leaves at the same general level plant C) the spread of viruses from trees and tall plants to bushes and other smaller plants, and horizontal transmission is the spread viruses among plants of similar size D) the transfer of DNA from a plant of one species to a plant of a different species, and horizontal transmission is the sprea among plants of the same species 2 What are prions? A) mobile segments of DNA B) tiny circular molecules of RNA that can infe C) viral DNA that attaches itself to the host genome and causes disease

Explanation / Answer

2. Option D. The protein on its surface and that of the host

Proteins on the surface of virus and host determine the antigen antibody reactions and other immunological interactions which determine the host range of virus. All other statements in the options like enzymes, nature of nucleic acid, proteins in host cytoplasm etc do not explain the host range of virus.

3. Option C. Control of more than one gene in an operon

The regulation mechanism of genes of bacteriophages is that there is control of more than one gene in an operon. Regulating via acetylation, positive control mechanisms, transcription activators are not expected in the genes of bacteriophage

4. Option C. A large number of phages are released at a time

Lytic cycle comprises of attachment of phage to host cell by tail fibers, penetration, biosynthesis, maturation and release of large number of phages. Hence, option C is the correct choice. All the other options are not the characteristics as seen above in the lytic cycle.

5. Option C. They have a single stranded RNA that acts as a template for DNA synthesis

Retrovirus is a single stranded positive sense RNA with a DNA intermediate which acts as obligate parasite infecting host cell. Retrovirus do not infect bacteria (bacteriophages infect bacteria), they are not made of single protein. Hence, the correct answer is Option C

6. Option A. It uses viral RNA as a template for DNA synthesis

Reverse transcriptase is located inside the protein coat on each of the RNA molecules and catalyzes the formation of DNA from a RNA template. Hence, the answer is option A

7. Option A. The viral envelope proteins would not have glycoproteins added to them and might not arrive at the host plasma membrane

8. Option B. The flu virus can be transmitted more easily from person to person than HIV

9. Option B. Vaccines are inactive versions of a virus that stimulate an immune reaction in a person

10. Option B. They can spread within a plant via plasmadesmata

11. Opton A. transmission of a virus from a parent plant to its progeny and horizontal transmission is one plant spreading the virus to another plant

12. Option D. misfolded versions of normal brain protein

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