Question 1

Viral cultivation is used for
A)diagnosis of viral infections.
B)preparation of vaccines.
C)producing adequate numbers of viruses for research purposes.
D)studying the viral life cycle within host cells.
E)observing the effects of viral infection on host cells.
F)All of these choices are correct.

Accepted Answer

Viral cultivation is a technique used for various purposes such as diagnosis of viral infections, preparation of vaccines, producing adequate numbers of viruses for research purposes, studying the viral life cycle within host cells, and observing the effects of viral infection on host cells. Therefore, all given choices are correct.

Question 2

What tool or technique used by Ivanowski and Beijerinck while studying diseased tobacco plants enabled them to determine that the disease was caused by an agent significantly smaller than bacteria?
A)scanning electron microscopy that enabled them to view the virus the tobacco mosaic virus
B)transmission electron microscopy that allowed them to view the tobacco mosaic virus
C)porcelain filters that trapped bacteria but allowed passage of the virus
D)cell culture that enabled cultivation of the virus

Accepted Answer

Ivanowski and Beijerinck used porcelain filters to trap bacteria but they found that the disease still passed through these filters. This led to the conclusion that the disease-causing agent was significantly smaller than bacteria and could only be a virus.

Question 3

While of the following techniques or tools has provided information regarding the nature of viruses, which one had to be developed before the genetics, biochemistry, and life cycles of viruses could be thoroughly studied?
A)scanning electron microscopy
B)viral cultivation techniques
C)transmission electron microscopy
D)serological techniques

Accepted Answer

Viral cultivation techniques had to be developed before the genetics, biochemistry, and life cycles of viruses could be thoroughly studied because they allowed scientists to grow and isolate viruses in the laboratory, which was essential for further research.

Question 4

Discuss theories regarding the origins of viruses and make a case for whether viruses originated before cellular life-forms or after cellular life-forms.

Accepted Answer

The answer of Discuss theories regarding the origins of viruses...

Question 5

The three basic groups of viruses based on morphology include
A)enveloped viruses, non enveloped viruses, and complex viruses.
B)enveloped viruses, DNA viruses, and non enveloped viruses.
C)helical viruses, round viruses, and enveloped viruses.
D)non enveloped viruses, RNA viruses, and bacteriophages.

Accepted Answer

The three basic groups of viruses based on morphology are enveloped viruses, non enveloped viruses, and complex viruses. Helical viruses and round viruses fall under the category of non enveloped viruses, while DNA viruses and RNA viruses fall under the category of complex viruses. Bacteriophages are a type of virus that infects bacteria and can fall under any of these categories depending on their morphology.

Question 6

Viral replication can involve the copying of RNA in an RNA virus.

Accepted Answer

RNA viruses replicate their genetic material using RNA-dependent RNA polymerase, which copies RNA to create new virions. This process is known as RNA replication.

Question 7

A common method for cultivating viruses in the lab is to use in vitro systems called _____ cultures.

Accepted Answer

The answer of A common method for cultivating viruses in...

Question 8

Which type of virus is most likely to cause the immediate damage and destruction of an infected animal cell when it is released?
A)enveloped virus
B)RNA virus
C)nonenveloped virus
D)DNA virus

Accepted Answer

Nonenveloped viruses are generally more stable and resistant to environmental stressors like heat, pH, and detergents. They also typically cause more immediate damage and destruction of infected cells upon release due to their ability to lyse cells and cause cell death. Enveloped viruses, on the other hand, are more fragile and typically require closer contact and entry into cells to cause damage. RNA and DNA viruses can both be enveloped or nonenveloped, so the type of nucleic acid does not necessarily determine the immediate damage potential.

Question 9

Compare and contrast the steps of viral multiplication cycles in bacteriophages and animal viruses.

Accepted Answer

The answer of Compare and contrast the steps of viral...

Question 10

Discuss why it is difficult to trace the origins of viruses and why they are important.

Accepted Answer

The answer of Discuss why it is difficult to trace...

Question 11

Discuss at least six characteristics that are unique to viruses compared to other microorganisms.

Accepted Answer

The answer of Discuss at least six characteristics that are...

Question 12

Noneveloped viruses enter their animal host cell via an active process that requires the participation of the animal cell.

Accepted Answer

Nonenveloped viruses do not have an outer membrane, so they require active participation from the host cell to enter. This is typically achieved through receptor-mediated endocytosis or membrane fusion. In contrast, enveloped viruses have a lipid membrane that can interact directly with the host cell membrane, allowing them to enter the cell without as much active participation from the host cell.

Question 13

A naked virus does not have a(n) _____.

Accepted Answer

The answer of A naked virus does not have a(n)...

Question 14

Select the FALSE statement about viruses.
A)Cellular life-forms most likely preceded the origin of viruses since viruses need host cells in which to develop and reproduce.
B)Viruses are the most numerous microbes on Earth.
C)Viruses have impacted the evolution of all other cellular life-forms including bacteria, achaeans, and eukaryotes.
D)When viruses are treated in a way that prevents them from entering host cells and reproducing, they are said to be dead.

Accepted Answer

Viruses are not considered living organisms and therefore cannot be classified as dead or alive. They are essentially just genetic material surrounded by a protein coat.

Question 15

Explain what is meant by host range, what governs host range, and what is meant by tissue tropism.

Accepted Answer

The answer of Explain what is meant by host range,...

Question 16

Discuss the criteria used for classifying viruses into families and genera.

Accepted Answer

The answer of Discuss the criteria used for classifying viruses...

Question 17

The descriptive groupings of virus into categories such as icosahedral and helical are based on
A)the type of nucleic acid.
B)the shape of the nucleocapsid.
C)the presence or absence of an envelope.
D)the mechanism of entry into host cells.

Accepted Answer

The descriptive groupings of virus into categories such as icosahedral and helical are based on the shape of the nucleocapsid. The nucleocapsid is the protein coat that encloses the viral genome.

Question 18

During lysogeny, an inactive prophage state occurs when the viral DNA is inserted into the _________.

Accepted Answer

The answer of During lysogeny, an inactive prophage state occurs...

Question 19

Which of the following viral types enter animal cells via fusion with the animal cell membrane?
A)enveloped viruses
B)non enveloped viruses
C)naked viruses
D)All of these choices are correct.

Accepted Answer

Enveloped viruses have an outer lipid bilayer, which fuses with the host cell membrane during viral entry. Non-enveloped and naked viruses do not have a lipid envelope and typically rely on receptor-mediated endocytosis to enter the host cell.

Question 20

Compare and contrast viruses, prions, and viroids.

Accepted Answer

The answer of Compare and contrast viruses, prions, and viroids....

Quiz 6: An Introduction to Viruses

Viral cultivation is used for

What tool or technique used by Ivanowski and Beijerinck while studying diseased tobacco plants enabled them to determine that the disease was caused by an agent significantly smaller than bacteria?

While of the following techniques or tools has provided information regarding the nature of viruses, which one had to be developed before the genetics, biochemistry, and life cycles of viruses could be thoroughly studied?