1.
Which of the following viruses are DNA viruses?
Correct Answer(s)
A. Pox
D. Hepadna
E. Herpes
Explanation
Pox, Hepadna, and Herpes viruses are DNA viruses. DNA viruses are a type of virus that have DNA as their genetic material. They replicate and reproduce by integrating their DNA into the host cell's DNA. Pox viruses cause diseases like smallpox and chickenpox. Hepadna viruses cause hepatitis B, and Herpes viruses cause diseases like cold sores and genital herpes. Retroviruses, such as HIV, and Corona viruses, like the one causing COVID-19, are RNA viruses, meaning they have RNA as their genetic material.
2.
Which of the following viruses are RNA viruses?
Correct Answer(s)
A. Entero
B. Paramyxo
E. Orthomyxo
Explanation
Entero, Paramyxo, and Orthomyxo viruses are RNA viruses. RNA viruses have RNA as their genetic material instead of DNA. Entero viruses belong to the Picornaviridae family and are responsible for causing gastrointestinal infections. Paramyxo viruses belong to the Paramyxoviridae family and can cause respiratory infections. Orthomyxo viruses belong to the Orthomyxoviridae family and are responsible for causing influenza or flu. Therefore, all three viruses mentioned in the answer (Entero, Paramyxo, and Orthomyxo) are RNA viruses.
3.
What is the name of the membrane surrounding the virus core?
Correct Answer
A. Envelope
Explanation
The correct answer is "Envelope." The envelope is a membrane that surrounds the virus core. It is composed of lipids and proteins and is derived from the host cell's membrane. The envelope plays a crucial role in protecting the virus and facilitating its entry into host cells. It also contains viral proteins that help in recognizing and binding to specific receptors on host cells.
4.
What is the name for the major protein component of the shell of the core?
Correct Answer
capsid
Explanation
The major protein component of the shell of the core is called the capsid.
5.
Viruses are considered ______
Correct Answer(s)
A. Smallest of all self-replicating organisms
B. Obligate intracellular parasites
C. Filterable infectious agents
Explanation
Viruses are considered the smallest of all self-replicating organisms because they are much smaller than bacteria and other microorganisms. They are also classified as obligate intracellular parasites because they can only replicate inside host cells and depend on the host's cellular machinery for their replication. Additionally, viruses are filterable infectious agents, meaning they can pass through filters that can trap bacteria and other larger microorganisms.
6.
Viruses always contain DNA as their genetic material.
Correct Answer
B. False
Explanation
Viruses contain DNA OR RNA encased in a protein shell
7.
Viruses use their protein synthesis machinery to synthesize proteins using host molecules.
Correct Answer
B. False
Explanation
They lack metabolic and protein synthesis machinery
8.
Which of the following is NOT a viral host?
Correct Answer
E. All of the above are viral hosts
Explanation
All of the options listed (bacteria, protozoa, fungi, and algae) can serve as viral hosts. This means that viruses can infect and replicate within these organisms. Therefore, none of the options provided are correct as they all represent viral hosts.
9.
What is the name for the smallest virus?
Correct Answer
Parvovirus
Explanation
20nm
10.
What is the name for the largest virus?
Correct Answer
Poxvirus
Explanation
450nm
11.
Which is NOT a viral structure?
Correct Answer
B. Hexagonal
Explanation
The hexagonal structure is not a viral structure. Viruses can have helical, ovoid, or icosahedral structures, but not hexagonal structures. Hexagonal structures are commonly found in crystals and other non-viral structures.
12.
The cells, tissues, species that a virus can productively infect is called _____
Correct Answer
host range
Explanation
The term "host range" refers to the range of cells, tissues, and species that a virus can infect and replicate within. It determines the specificity of a virus and its ability to cause infection in different organisms. The host range can vary widely among viruses, with some being able to infect a broad range of hosts, while others are more restricted and can only infect specific species or cell types. Understanding the host range of a virus is crucial in studying its transmission, pathogenesis, and developing effective prevention and treatment strategies.
13.
The capacity of a cell, tissue, or species to support virus replication is called _____
Correct Answer
susceptibility
Explanation
Susceptibility refers to the ability of a cell, tissue, or species to support virus replication. It indicates the vulnerability or receptiveness of an organism to being infected by a virus. Susceptibility is determined by various factors such as the presence or absence of specific receptors on the host cells, the immune response of the host, and the genetic makeup of the host.
14.
The ability of a virus to infect a host is determined by what?
Correct Answer(s)
A. Host cell receptor availability
B. Presence of intracellular host cell factors
Explanation
The ability of a virus to infect a host is determined by the availability of host cell receptors and the presence of intracellular host cell factors. Host cell receptors are proteins on the surface of the host cell that the virus uses to attach and enter the cell. If the receptors are not available or are not compatible with the virus, infection cannot occur. Additionally, intracellular host cell factors are necessary for the virus to replicate and complete its life cycle inside the host cell. Without these factors, the virus cannot successfully infect the host.
15.
The purpose of this structure is to form a stable protective shell for the genome.
Correct Answer(s)
capsid
Explanation
The capsid is the protein shell that surrounds and protects the genome of a virus. It provides stability and protection to the genetic material inside, preventing it from being damaged or degraded. The capsid also plays a crucial role in the virus's ability to infect host cells, as it contains specific receptors that allow the virus to attach to and enter target cells. Overall, the purpose of the capsid is to form a stable protective shell for the genome, ensuring the survival and successful replication of the virus.
16.
What is the name for the discrete substructure of the virion which contains a nucleic acid-protein assembly package?
Correct Answer(s)
nucleocapsid
Explanation
The discrete substructure of the virion that contains a nucleic acid-protein assembly package is called the nucleocapsid. This term refers to the combination of the viral nucleic acid (DNA or RNA) and the proteins that surround and protect it. The nucleocapsid plays a crucial role in the structure and stability of the virion, as well as in the transmission and replication of the viral genome.
17.
An icosahedral structure contains which of the following?
Correct Answer(s)
A. 5-fold axis of symmetry
C. 3-fold axis of symmetry
D. 2-fold axis of symmetry
Explanation
An icosahedral structure contains 5-fold, 3-fold, and 2-fold axes of symmetry. This means that the structure can be rotated by certain angles around these axes and still appear the same. The 5-fold axis of symmetry indicates that the structure can be rotated by 72 degrees and still look the same. The 3-fold axis of symmetry means that the structure can be rotated by 120 degrees and still maintain its appearance. Lastly, the 2-fold axis of symmetry implies that the structure can be rotated by 180 degrees and still have the same visual characteristics.
18.
How many vertices does the icosahedron contain?
Correct Answer(s)
12
Explanation
An icosahedron is a three-dimensional geometric shape that consists of 20 equilateral triangular faces. Each vertex of the icosahedron is where three of these triangular faces meet. Since each face has three vertices, and there are 20 faces in total, the icosahedron contains a total of 12 vertices.
19.
How many triangular faces does the icosahedron contain?
Correct Answer(s)
20
Explanation
An icosahedron is a geometric solid with 20 equilateral triangular faces. Each face of the icosahedron is a separate triangle, and there are a total of 20 of these triangular faces. Therefore, the correct answer is 20.
20.
A host cell-derived lipid bilayer carrying viral glycoproteins that forms the outer layer of a virus particle.
Correct Answer(s)
envelope
Explanation
The correct answer is "envelope." An envelope refers to a host cell-derived lipid bilayer that surrounds a virus particle and is embedded with viral glycoproteins. This outer layer provides protection to the virus and helps it to enter and infect host cells. The envelope is essential for the survival and replication of certain viruses, such as the influenza virus and HIV.
21.
Most viruses acquire their membrane by forming a lipid bilayer from their glycoproteins.
Correct Answer
B. False
Explanation
Most viruses acquire their membrane by budding through a host cell membrane (plasma, ER, golgi, or nuclear)
22.
Viral envelope proteins are targeted to the appropriate membrane during translation.
Correct Answer
B. False
Explanation
They are post-translationally targeted to the appropriate membrane
23.
Enveloped viruses enter the host via which mechanism of entry?
Correct Answer
A. Fusion with the plasma membrane
Explanation
Enveloped viruses enter the host via fusion with the plasma membrane. This process involves the viral envelope fusing with the host cell's plasma membrane, allowing the viral genetic material to enter the host cell. This mechanism of entry is commonly used by enveloped viruses, which have a lipid envelope derived from the host cell membrane. Fusion with the plasma membrane allows the virus to bypass the need for endocytosis or penetration through the plasma membrane, making it an efficient method for viral entry into the host cell.
24.
Non-enveloped viruses enter the host via which entry mechanism?
Correct Answer
C. Penetration through plasma membrane
Explanation
Non-enveloped viruses enter the host via penetration through the plasma membrane. Unlike enveloped viruses, which fuse with the host cell's plasma membrane or enter through endocytosis, non-enveloped viruses directly penetrate the plasma membrane to gain entry into the host cell. This allows the viral genetic material to be released into the host cell's cytoplasm, where it can hijack the host's cellular machinery for replication and production of new viral particles.
25.
In viral endocytosis, what causes the conformation change which releases the virus from the endosome into the cytosol?
Correct Answer
pH
Explanation
The conformation change that releases the virus from the endosome into the cytosol is caused by pH. This is because the low pH environment in the endosome triggers a structural change in the viral protein, allowing it to fuse with the endosomal membrane and release the viral genome into the cytosol. The acidic pH of the endosome is essential for the viral entry process and is a common mechanism used by many viruses to deliver their genetic material into the host cell.
26.
Partial uncoating typically is used in the formation of the virus replication complex.
Correct Answer
A. True
Explanation
Partial uncoating refers to the process by which a virus sheds some of its protein coat after entering a host cell. This shedding allows the virus to expose its genetic material and begin replicating. In the context of the question, it suggests that partial uncoating is a common step in the formation of the virus replication complex. This complex is responsible for the replication and assembly of new virus particles. Therefore, the statement is true as partial uncoating is indeed used in the formation of the virus replication complex.
27.
While viral uncoating is a poorly understood process, it is thought to be initiated by cellular signals such as receptor binding and pH change.
Correct Answer
A. True
Explanation
The explanation for the given correct answer is that viral uncoating, which refers to the process of removing the viral capsid or envelope, is not well understood. However, it is believed that this process is triggered by certain signals from the host cell, such as receptor binding and changes in pH. Therefore, it is true that viral uncoating is thought to be initiated by cellular signals.
28.
RNA viral replication normally occurs where?
Correct Answer
C. Cytosol
Explanation
RNA viral replication normally occurs in the cytosol. This is because RNA viruses do not have the ability to enter the nucleus of the host cell, where DNA replication takes place. Instead, they replicate their genetic material and assemble new viral particles in the cytosol, which is the fluid-filled region of the cell outside the nucleus. The cytosol provides the necessary cellular machinery and resources for viral replication to occur efficiently.
29.
Replication of progeny genomic RNA molecules uses host RNA polymerase
Correct Answer
B. False
Explanation
Uses viral specific RNA polymerase
30.
DNA viral replication typically occurs where?
Correct Answer
A. Nucleus
Explanation
DNA viral replication typically occurs in the nucleus of the host cell. This is because the nucleus contains all the necessary cellular machinery and resources required for DNA replication. Additionally, the nucleus provides a controlled and protected environment for the replication process to occur.
31.
DNA viruses always use the host cell machinery for replication.
Correct Answer
B. False
Explanation
It may or may not depending on whether the virus carries a DNA polymerase.
32.
The synthesis of RNA and DNA viral proteins relies on host machinery.
Correct Answer
A. True
Explanation
The given statement is true because RNA and DNA viral proteins cannot be synthesized without the help of host machinery. Viruses do not have their own cellular machinery to carry out protein synthesis, so they rely on the host cell's machinery to replicate their genetic material and produce viral proteins. This allows the viruses to hijack the host cell's resources and use them for their own replication and survival.
33.
The viral genome is typically incorporated at what point?
Correct Answer
C. As the core is assembled
Explanation
The viral genome is typically incorporated as the core of the virus is assembled. This means that as the virus is being formed, the viral genome is also being packaged and included within the viral core. This is a crucial step in the viral life cycle, as the viral genome contains the genetic information necessary for the virus to replicate and infect host cells. By incorporating the genome during core assembly, the virus ensures that its genetic material is protected and ready to be delivered to the host cell upon infection.
34.
For enveloped viruses, assembly typically occurs at the site of membrane acquisition
Correct Answer
A. True
Explanation
Enveloped viruses are a type of virus that have an outer lipid membrane derived from the host cell. This membrane is acquired during the process of assembly, where the viral components come together to form a complete virus particle. The assembly of enveloped viruses typically occurs at the site of membrane acquisition, which means that the viral components gather and arrange themselves on the host cell's membrane. This allows the virus to incorporate the host cell's membrane into its own structure, forming the characteristic envelope. Therefore, the statement "For enveloped viruses, assembly typically occurs at the site of membrane acquisition" is true.
35.
Which release mechanism involves the accumulation of particles until critical mass is achieved?
Correct Answer
A. Lytic
Explanation
Viral signals induce cell death and release of virions
36.
The majority of viruses result in mild symptoms.
Correct Answer
B. False
Explanation
The majority of viruses cause no disease
37.
Which are common manifestations of viral disease?
Correct Answer(s)
A. Rashes
B. Fever
C. Muscle aches
D. Swollen lymph nodes
Explanation
These are common manifestations of viral disease because viruses can cause inflammation and immune responses in the body, leading to symptoms such as rashes, fever, muscle aches, and swollen lymph nodes.
38.
Body defenses involve the combined action of _____
Correct Answer(s)
A. Interferon
C. Antibodies
D. Cytotoxic T cells
Explanation
Helper T cells may be involved but were not included in the slide
39.
(Chronic/Latent) Infections have detectable virus in tissue samples
Correct Answer(s)
chronic
Explanation
Chronic infections are characterized by the presence of detectable virus in tissue samples. This means that even after the initial infection, the virus remains in the body and can be detected in tissues. This is different from latent infections where the virus is present but not actively replicating or causing symptoms. In chronic infections, the virus continues to replicate and can potentially cause long-term health issues.
40.
(Chronic/Latent) infections generally occur after a lytic cycle.
Correct Answer(s)
latent
Explanation
Latent infections generally occur after a lytic cycle refers to the fact that latent infections, where the virus remains dormant in the host's cells without causing symptoms, typically follow an initial lytic cycle. In the lytic cycle, the virus actively replicates and causes cell lysis, leading to the release of new viral particles. After this initial phase, some viruses can enter a latent state where they remain in the host's cells without causing immediate harm. Therefore, the correct answer is latent.
41.
(Chronic/Latent) infections can reactivate and result in recurrent infections
Correct Answer(s)
latent
Explanation
Latent infections can reactivate and result in recurrent infections. This means that even though the infection may be dormant or inactive for a period of time, it can become active again and cause recurrent episodes of infection. This is often seen in viral infections such as herpes, where the virus can remain in a dormant state in the body and then reactivate, leading to recurrent outbreaks.
42.
(Chronic/Latent) infections multiply at a slow rate
Correct Answer(s)
chronic
Explanation
Chronic infections are characterized by a slow multiplication rate. Unlike acute infections, where the pathogen rapidly multiplies and causes severe symptoms, chronic infections progress slowly and can last for a long time. The slow rate of multiplication allows the pathogen to persist in the body, often evading the immune system's defenses. This can lead to prolonged or recurring symptoms, as well as potential long-term complications. Therefore, the given answer "chronic" aligns with the statement that chronic infections multiply at a slow rate.
43.
Which are considered possible effects of viral infections on host cells?
Correct Answer(s)
A. Transformation
B. Chronic infection
C. Asymptomatic
D. Lytic
Explanation
Viral infections can have various effects on host cells. Transformation refers to the process where the virus alters the genetic material of the host cell, leading to abnormal growth and potentially causing cancer. Chronic infection occurs when the virus persists in the host for a long time, continuously replicating and causing ongoing damage. Asymptomatic infections occur when the host shows no symptoms despite being infected, allowing the virus to spread unknowingly. Lytic infections involve the virus entering the host cell, replicating, and then causing the cell to burst, releasing new viral particles. These effects collectively demonstrate the range of possible consequences of viral infections on host cells.
44.
The best target for treatment of viral diseases is the viral membrane
Correct Answer
B. False
Explanation
Best targets are unique viral enzymes
45.
What category of viral treatment options are immune modulating drugs?
Correct Answer
interferons
Explanation
Interferons are immune modulating drugs that belong to the category of viral treatment options. They work by enhancing the body's immune response to fight against viral infections. Interferons help to regulate the immune system and inhibit the replication of viruses, thereby reducing the severity and duration of viral illnesses. These drugs are commonly used in the treatment of various viral infections, including hepatitis B and C, as well as some forms of cancer.
46.
Ribavirin is a viral treatment which is a synthetic analog of _____
Correct Answer
B. Guanosine
Explanation
Ribavirin is a viral treatment that is a synthetic analog of guanosine. This means that ribavirin is structurally similar to guanosine, a nucleoside found in RNA. By mimicking guanosine, ribavirin can interfere with viral replication and inhibit the growth of certain viruses.
47.
Which drug is approved in the US for respiratory syncytial virus (RSV) and in combination with alpha interferon for HCV?
Correct Answer
A. Ribavirin
Explanation
Ribavirin is the correct answer because it is approved in the US for the treatment of respiratory syncytial virus (RSV) and in combination with alpha interferon for hepatitis C virus (HCV). Ribavirin is an antiviral medication that works by inhibiting the replication of the virus, making it an effective treatment for both RSV and HCV. Beta interferon 1, acyclovir, and ritonavir are not approved for these specific indications.
48.
Ribavirin is a viral treatment used solely for RNA viruses.
Correct Answer
B. False
Explanation
DNA and RNA
49.
Ribavirin has multiple mechanisms of action
Correct Answer
A. True
Explanation
Nucleoside analog, capping and elongation of RNA (RNA polymerase inhibitor), reverse transcription inhibitor
50.
(Enveloped/Nonenveloped) DNA viruses can be double-stranded or single-stranded.
Correct Answer
nonenveloped
Explanation
Nonenveloped DNA viruses can be either double-stranded or single-stranded. The term "nonenveloped" refers to the lack of an outer lipid membrane surrounding the viral capsid. This type of virus is more resistant to harsh environmental conditions and can survive outside the host for longer periods. The fact that nonenveloped DNA viruses can have either double-stranded or single-stranded genomes highlights the diversity and adaptability of this group of viruses.