1.
The only viral disease that has been totally eradicated is Smallpox disease.
Correct Answer
A. True
Explanation
Smallpox is the only viral disease that has been completely eradicated. Through a global vaccination campaign, the World Health Organization successfully eliminated the smallpox virus in 1980. This achievement is a testament to the effectiveness of vaccines and the collaborative efforts of the international community in eradicating a deadly disease. Other viral diseases, such as polio and measles, are still present in some parts of the world, highlighting the significance of ongoing vaccination efforts to control and eliminate infectious diseases.
2.
Certain viruses can be used as a gene vector for the treatment of genetic diseases.
Correct Answer
A. True
Explanation
Certain viruses can be used as gene vectors for the treatment of genetic diseases. This is because viruses have the ability to infect cells and insert their genetic material into the host cell's DNA. By modifying the genetic material carried by the virus, scientists can use it to deliver therapeutic genes into specific cells in the body. This approach holds promise for treating genetic diseases by replacing or correcting faulty genes.
3.
The smallest virions of viruses belong to herpesviruses.(20 nm in size)
Correct Answer
B. False
Explanation
The statement is false because the smallest virions of viruses do not belong to herpesviruses. The size of herpesviruses is generally larger than 20 nm. The smallest known virus is the circovirus, which has a size of around 17-20 nm. Therefore, the correct answer is false.
4.
Protease and reverse transcriptase are examples of virus structural proteins.
Correct Answer
B. False
Explanation
Protease and reverse transcriptase are not examples of virus structural proteins. Protease is an enzyme that helps in the replication of viruses by cleaving viral proteins, while reverse transcriptase is an enzyme that helps in the replication of retroviruses by converting viral RNA into DNA. Structural proteins of viruses are responsible for the physical structure and integrity of the virus particle, such as the capsid or envelope proteins.
5.
The capsids of herpesviruses are in icosahedral shape.
Correct Answer
A. True
Explanation
The explanation for the given answer "True" is that herpesviruses have capsids that are in an icosahedral shape. The term "icosahedral" refers to a geometric shape with 20 triangular faces, 12 vertices, and 30 edges. This shape is commonly observed in viruses, including herpesviruses, as it provides structural stability and efficient packaging of the viral genetic material. Therefore, it is correct to say that the capsids of herpesviruses are in an icosahedral shape.
6.
Chikungunya viruses are transmitted between hosts by inanimate vectors.
Correct Answer
B. False
Explanation
Chikungunya viruses are not transmitted between hosts by inanimate vectors. They are primarily transmitted to humans by infected mosquitoes, specifically the Aedes aegypti and Aedes albopictus species. These mosquitoes become infected when they feed on a person infected with the virus, and then they can transmit it to other people through their bites. Therefore, the statement is false.
7.
Positive (+) sense ssRNA can acts directly as mRNA for protein synthesis.
Correct Answer
A. True
Explanation
Positive sense ssRNA can act directly as mRNA for protein synthesis because it carries the genetic information that is used by ribosomes to synthesize proteins. Unlike negative sense ssRNA, which needs to be converted into positive sense RNA before it can serve as mRNA, positive sense ssRNA can be immediately translated into proteins. This is because its sequence is already compatible with the ribosome's protein synthesis machinery. Therefore, positive sense ssRNA can directly initiate the process of protein synthesis without any additional steps.
8.
The enhancers of many virus genes contain sequence of TATA[A/T]A[A/T][A/G]
Correct Answer
B. False
Explanation
The enhancers of many virus genes do not necessarily contain the specific sequence TATA[A/T]A[A/T][A/G]. Therefore, the statement is false.
9.
Transcription factors are proteins responsible to control the expression of genes.
Correct Answer
A. True
Explanation
Transcription factors are indeed proteins that regulate the expression of genes. They bind to specific DNA sequences and either promote or inhibit the transcription of genes, thereby controlling the production of proteins. By binding to the promoter region of a gene, transcription factors can either enhance or suppress the initiation of transcription by RNA polymerase. This regulation is crucial for the proper functioning and development of cells and organisms. Therefore, the statement "Transcription factors are proteins responsible to control the expression of genes" is true.
10.
Polyadenylation of transcripts occurs at the 3’-end of most viruses.
Correct Answer
A. True
Explanation
Polyadenylation refers to the addition of a poly(A) tail at the 3'-end of an mRNA molecule. This process is common in most viruses, where it plays a crucial role in stabilizing the mRNA and regulating its translation. The poly(A) tail helps protect the mRNA from degradation and allows it to be efficiently exported from the nucleus to the cytoplasm for translation. Therefore, the statement that polyadenylation of transcripts occurs at the 3'-end of most viruses is true.
11.
Glycosylation involves the addition of acyl group to the newly formed viral protein.
Correct Answer
B. False
Explanation
Glycosylation is a process in which sugar molecules are added to proteins or lipids. It does not involve the addition of an acyl group, which is a functional group consisting of a carbon atom bonded to a oxygen atom and a double-bonded oxygen atom. Therefore, the statement that glycosylation involves the addition of an acyl group to the newly formed viral protein is false.
12.
Replication for many RNA viruses does not require a primer.
Correct Answer
A. True
Explanation
Many RNA viruses have the ability to replicate their genetic material without the need for a primer. This means that they can initiate the replication process directly from their RNA genome without the requirement of an additional molecule to start the synthesis. This is in contrast to DNA viruses, which typically require a primer for replication. The ability of RNA viruses to replicate without a primer is due to the presence of specific enzymes, such as RNA-dependent RNA polymerase, which can recognize the viral RNA and initiate the replication process. Therefore, the statement that replication for many RNA viruses does not require a primer is true.
13.
The key enzyme in viral genome replication is transcriptases.
Correct Answer
B. False
14.
The Okazaki fragments formed in lagging strands are joined together by DNA ligase.
Correct Answer
A. True
Explanation
Okazaki fragments are short segments of DNA that are synthesized discontinuously on the lagging strand during DNA replication. These fragments are later joined together by an enzyme called DNA ligase. This process is essential for completing the replication of the lagging strand and ensuring the integrity of the newly synthesized DNA molecule. Therefore, the statement that Okazaki fragments formed in lagging strands are joined together by DNA ligase is true.
15.
Reverse transcription processes only occur in Retroviruses and Hepadnaviruses.
Correct Answer
A. True
Explanation
Reverse transcription is the process by which RNA is converted into DNA. This process is unique to retroviruses and hepadnaviruses, as they are the only viruses known to have the enzyme called reverse transcriptase. Reverse transcriptase allows these viruses to convert their RNA genome into DNA, which can then be integrated into the host cell's genome. This ability is not found in other types of viruses, making the statement true.
16.
An mRNA can be a positive and negative strands in viruses.
Correct Answer
B. False
Explanation
An mRNA (messenger RNA) is a single-stranded molecule that carries genetic information from DNA to the ribosomes for protein synthesis. In viruses, mRNA is typically only a positive strand, meaning it has the same sequence as the coding strand of DNA. The negative strand, which has a complementary sequence to the coding strand, is usually used as a template for mRNA synthesis. Therefore, the statement that an mRNA can be both positive and negative strands in viruses is incorrect.
17.
Gene products and regulatory signals for attachment to the right cell.
Correct Answer
A. True
Explanation
The statement suggests that gene products and regulatory signals are necessary for attachment to the right cell. This implies that specific genes and their products play a role in determining which cells an organism can attach to. Additionally, regulatory signals likely control the expression and activity of these genes, further influencing cell attachment. Therefore, the answer "True" indicates that gene products and regulatory signals are indeed important for attachment to the right cell.
18.
The genetic code in the viral sequence encodes for complete protein synthesis.
Correct Answer
B. False
Explanation
The statement is false because viral sequences do not encode for complete protein synthesis. Viruses are obligate intracellular parasites that rely on host cells for their replication and protein synthesis. They typically carry only a subset of genes necessary for their replication and rely on host cellular machinery to complete the protein synthesis process. Therefore, the genetic code in viral sequences does not encode for complete protein synthesis.
19.
Virions are animate but they have no powers of locomotion.
Correct Answer
B. False
Explanation
Virions are not animate as they are non-living particles made up of genetic material (DNA or RNA) enclosed in a protein coat. They cannot carry out any metabolic activities or reproduce on their own. Additionally, since they lack locomotion, they cannot move or travel independently. Therefore, the statement "Virions are animate but they have no powers of locomotion" is incorrect.
20.
A retrovirus uses sialic acid as the receptor to attach to the specific cell of interest.
Correct Answer
B. False
Explanation
Retroviruses typically use specific cell surface receptors, such as CD4 or CXCR4, to attach to the target cell. Sialic acid is not a receptor used by retroviruses for attachment. Therefore, the statement that a retrovirus uses sialic acid as the receptor is false.
21.
Coxsackievirus group B viruses require two receptors which are a decay-accelerating factor (DAF) and coxsackievirus-adenovirus receptor.
Correct Answer
A. True
Explanation
Coxsackievirus group B viruses require two receptors, the decay-accelerating factor (DAF) and the coxsackievirus-adenovirus receptor, for their entry into host cells. This means that both receptors are necessary for the virus to successfully infect and replicate within a host. Therefore, the statement "Coxsackievirus group B viruses require two receptors which are a decay-accelerating factor (DAF) and coxsackievirus-adenovirus receptor" is true.
22.
Viral components can visibly see under the light microscope in cell smears.
Correct Answer
A. True
Explanation
Viral components can be seen under a light microscope in cell smears. This is because viruses are microscopic infectious agents that can be observed using a light microscope. Cell smears are prepared by spreading a thin layer of cells on a slide, which allows for easier visualization of viral components such as viral particles or viral inclusions. Therefore, it is true that viral components can be visibly seen under a light microscope in cell smears.
23.
Most enveloped viruses acquire the envelope after the assembly of internal structures.
Correct Answer
A. True
Explanation
Enveloped viruses are a type of virus that have an outer lipid membrane, or envelope, surrounding their genetic material and proteins. This envelope is acquired by the virus after the assembly of its internal structures. During the assembly process, the virus produces and assembles its structural components, such as the capsid and genetic material, and then acquires the envelope by budding from the host cell membrane or an intracellular membrane. This process allows the virus to acquire its envelope and become fully infectious. Therefore, the statement "Most enveloped viruses acquire the envelope after the assembly of internal structures" is true.
24.
Influenza virus assembles their particles and secreted out from the cell through budding movement.
Correct Answer
A. True
Explanation
The statement is true because influenza viruses do assemble their particles and are then secreted out from the cell through a process called budding. During budding, the viral particles acquire a lipid envelope from the host cell membrane and are released from the cell, allowing them to infect other cells. This is a characteristic feature of the influenza virus life cycle.
25.
Virally infected cells lysed because of the inhibition of cell micromolecular processes and transport.
Correct Answer
B. False
Explanation
The statement suggests that virally infected cells lysed due to the inhibition of cell micromolecular processes and transport. However, this is not true. Virally infected cells typically undergo lysis due to the replication and release of new viral particles, not because of the inhibition of cell micromolecular processes and transport.
26.
Microorganisms may enter the body and cause illness before the immune system can destroy them.
Correct Answer
A. True
Explanation
Microorganisms are capable of entering the body and causing illness before the immune system can effectively eliminate them. This is because the immune response takes time to recognize and mount a defense against the invading pathogens. During this time, the microorganisms can multiply and spread, leading to the development of symptoms and illness. Therefore, it is true that microorganisms may enter the body and cause illness before the immune system can destroy them.
27.
Vaccinations provide protection from microorganisms by creating antibiotics before infection.
Correct Answer
B. False
Explanation
This statement is incorrect. Vaccinations provide protection from microorganisms by stimulating the immune system to produce antibodies specific to the particular microorganism. Antibiotics, on the other hand, are medications used to treat bacterial infections, not prevent them. Therefore, the correct answer is False.
28.
A vaccination contains a usually unsafe form of a disease-causing microorganism.
Correct Answer
B. False
Explanation
A vaccination typically contains a weakened or inactivated form of a disease-causing microorganism, rather than an unsafe form. This is done to stimulate the immune system without causing illness. By introducing a harmless version of the microorganism, the body can develop an immune response and build immunity against the actual disease-causing form. Therefore, the statement that a vaccination contains a usually unsafe form of a disease-causing microorganism is false.
29.
Vaccination can never be completely safe since individuals have different degrees of side effects from a vaccine.
Correct Answer
A. True
Explanation
This statement is true because individuals can have varying degrees of side effects from a vaccine. While vaccines are generally considered safe and effective, there can be rare cases where individuals may experience adverse reactions. These side effects can range from mild, such as soreness at the injection site, to more severe reactions. Therefore, it is important to consider individual differences and potential risks when assessing the safety of vaccinations.
30.
To prevent epidemics of infectious diseases, it is only necessary to vaccinate a small percentage of a population so that the infection cannot spread easily.
Correct Answer
B. False
Explanation
This statement is false. Vaccinating a small percentage of the population is not sufficient to prevent epidemics of infectious diseases. In order to achieve herd immunity and effectively prevent the spread of infections, a large majority of the population needs to be vaccinated. This is because vaccines not only protect the individual receiving it, but also help to reduce the overall transmission of the disease within a community. Therefore, a high vaccination coverage is necessary to ensure the effectiveness of vaccination programs in preventing epidemics.
31.
New vaccines against influenza have to be developed regularly because the virus changes its antigens very quickly.
Correct Answer
A. True
Explanation
Influenza virus is known to change its antigens quickly through a process called antigenic drift. This means that the surface proteins on the virus, which are targeted by the immune system, can change over time. As a result, the antibodies produced by previous vaccinations may not be effective against the new strains of the virus. Therefore, new vaccines need to be developed regularly to match the updated antigens and provide effective protection against the evolving influenza virus.
32.
It is difficult to develop an effective vaccine against the HIV virus (which causes AIDS) because the virus damages the immune system and has a high mutation rate. Mutations produce changes to its antigens.
Correct Answer
A. True
Explanation
Developing an effective vaccine against the HIV virus is challenging due to two main reasons. Firstly, the virus damages the immune system, making it harder for the body to mount an effective immune response. Secondly, the HIV virus has a high mutation rate, meaning it can rapidly change its antigens. This makes it difficult for a vaccine to target the virus effectively, as the antigens it produces may be different from the ones targeted by the vaccine. Therefore, the statement that it is difficult to develop an effective vaccine against the HIV virus due to immune system damage and high mutation rate is true.
33.
MMR is an example of a vaccination where there has been controversy over its safety.
Correct Answer
A. True
Explanation
The statement is true because MMR (Measles, Mumps, and Rubella) vaccination has indeed been a topic of controversy regarding its safety. Some groups have raised concerns about potential side effects and a possible link to autism, although numerous scientific studies have consistently shown no such association. Despite the overwhelming evidence supporting its safety and effectiveness, the controversy has led to vaccine hesitancy and a decline in vaccination rates in some communities, resulting in outbreaks of these preventable diseases.
34.
Vaccinations cannot be used against papillomaviruses.
Correct Answer
B. False
Explanation
Vaccinations can be used against papillomaviruses. Vaccines such as the HPV vaccine have been developed to protect against certain types of papillomaviruses that can cause cervical cancer, genital warts, and other diseases. These vaccines stimulate the immune system to produce antibodies that can recognize and attack the virus, preventing infection and its associated health risks. Therefore, the statement that vaccinations cannot be used against papillomaviruses is false.
35.
Microorganisms with a high mutation rate may change their antigens frequently making a vaccination less effective.
Correct Answer
A. True
Explanation
Microorganisms with a high mutation rate have the ability to change their antigens frequently. Antigens are the molecules on the surface of microorganisms that trigger an immune response. Vaccines are designed to stimulate the immune system to recognize and target specific antigens. However, if the antigens of a microorganism change frequently due to mutations, the immune system may not be able to recognize and target them effectively. This can make a vaccination less effective in providing protection against the microorganism. Therefore, the statement is true.
36.
Virus infection can be diagnosed using fluorescence microscopy.
Correct Answer
A. True
Explanation
Fluorescence microscopy can be used to diagnose virus infections because certain viruses can be labeled with fluorescent dyes or antibodies that specifically bind to the virus. When the sample is viewed under a fluorescence microscope, the labeled viruses will emit a fluorescent signal, allowing for their detection and identification. This technique is commonly used in research and clinical settings to diagnose viral infections.
37.
Definitive identification of most fungi is based on the morphology of reproductive structure (spores).
Correct Answer
A. True
Explanation
The statement is true because the definitive identification of most fungi relies on examining the morphology of their reproductive structures, specifically their spores. Spores are unique to each species and can provide important clues for identifying and classifying fungi. By studying the shape, size, color, and other characteristics of spores, scientists can determine the specific species of fungi. This method is widely used in mycology (the study of fungi) and is considered a reliable way to identify fungi.
38.
Lactophenol cotton blue is the most common staining agent used in the preparation of slides for microscopic examination of yeast.
Correct Answer
B. False
Explanation
Lactophenol cotton blue is not the most common staining agent used in the preparation of slides for microscopic examination of yeast. Other staining agents, such as methylene blue or potassium hydroxide, are often used for this purpose. Therefore, the correct answer is false.
39.
Viral hemagglutination is used to detect the presence of virus-specific antibodies.
Correct Answer
A. True
Explanation
Viral hemagglutination is a technique used to detect the presence of virus-specific antibodies. This process involves mixing red blood cells with a virus and observing if the red blood cells clump together (hemagglutination) due to the binding of virus-specific antibodies. If clumping occurs, it indicates the presence of these antibodies and suggests a previous viral infection or immunization. Therefore, the statement is true.
40.
The polymerase chain reaction is commonly used to identify pathogenic dimorphic fungi.
Correct Answer
B. False
Explanation
The polymerase chain reaction (PCR) is a technique used to amplify specific DNA sequences, not to identify pathogenic dimorphic fungi. PCR can be used to detect and identify various types of microorganisms, including fungi, but it is not specific to dimorphic fungi. Other methods, such as culture or microscopy, are typically used to identify pathogenic dimorphic fungi. Therefore, the given statement is false.
41.
Most serological test for fungi has measured the antibody rather than detection of the antigen.
Correct Answer
A. True
Explanation
Serological tests for fungi typically measure the presence of antibodies in the blood, rather than directly detecting the antigens produced by the fungi. This is because the immune system responds to fungal infections by producing antibodies, which can be detected in a blood sample. By measuring the presence and levels of these antibodies, serological tests can help diagnose fungal infections. Therefore, the statement that most serological tests for fungi measure the antibody rather than the detection of the antigen is true.
42.
Potato dextrose agar is a culture media of choice to culture fungi.
Correct Answer
B. False
Explanation
Potato dextrose agar is not the culture media of choice to culture fungi. Although it can support the growth of some fungi, it is not the most preferred medium for fungal culture. Sabouraud dextrose agar is commonly used as the culture media of choice for fungi due to its low pH and high dextrose concentration, which inhibits the growth of bacteria and promotes the growth of fungi. Therefore, the statement is false.
43.
The plaque assay can be used to quantitate the infectious titer of viruses.
Correct Answer
A. True
Explanation
The plaque assay is a commonly used technique to determine the concentration of infectious viruses in a sample. It involves infecting a monolayer of host cells with a dilution of the virus sample, allowing the virus to replicate and form visible plaques, which are areas of cell death. By counting the number of plaques, the titer, or concentration, of infectious virus particles can be calculated. Therefore, the statement that the plaque assay can be used to quantitate the infectious titer of viruses is true.
44.
Reverse transcriptase (RT) PCR is the rapid identification of dengue virus in acute-phase serum.
Correct Answer
A. True
Explanation
Reverse transcriptase (RT) PCR is a technique used to detect and amplify RNA molecules, making it useful for identifying RNA viruses like the dengue virus. In the case of dengue virus, RT-PCR can be used to detect the presence of the virus in the acute-phase serum of an infected individual. This method is rapid and sensitive, allowing for early diagnosis of dengue infection. Therefore, the statement that RT-PCR is the rapid identification of dengue virus in acute-phase serum is true.
45.
All types of viruses can be isolated and propagated in cell culture.
Correct Answer
B. False
Explanation
Not all types of viruses can be isolated and propagated in cell culture. Some viruses require specific conditions or host cells to replicate and cannot be grown in cell cultures. Therefore, the statement is false.
46.
Hepatitis B surface antigen (HBsAg) cannot be used as a peptide vaccine.
Correct Answer
B. False
Explanation
The statement is false because Hepatitis B surface antigen (HBsAg) can be used as a peptide vaccine. Peptide vaccines are made by using small fragments of proteins, called peptides, to stimulate an immune response against a specific pathogen. HBsAg is a protein found on the surface of the hepatitis B virus, and it can be used as a peptide vaccine to trigger an immune response and protect against hepatitis B infection.
47.
The scientist who discovered vaccination was Louis Pasteur.
Correct Answer
B. False
Explanation
The statement is false because the scientist who discovered vaccination was not Louis Pasteur. The credit for discovering vaccination goes to Edward Jenner. In the late 18th century, Jenner developed the smallpox vaccine by using cowpox virus to protect against smallpox. Pasteur, on the other hand, made significant contributions to the field of microbiology and is known for his work on pasteurization and developing vaccines for diseases like rabies and anthrax.
48.
A phylogenetic tree can be used to indicate the relationship between viruses.
Correct Answer
A. True
Explanation
A phylogenetic tree is a diagram that shows the evolutionary relationships between different organisms or groups of organisms. It is based on the analysis of genetic similarities and differences. Viruses can also be represented on a phylogenetic tree to indicate their evolutionary relationships. This is because viruses also have genetic material that can be analyzed to determine their similarities and differences. Therefore, it is true that a phylogenetic tree can be used to indicate the relationship between viruses.
49.
Paramyxoviridae is a family of viruses with negative (-) sense ssRNA.
Correct Answer
B. False
Explanation
Paramyxoviridae is a family of viruses with negative (-) sense ssRNA. Therefore, the correct answer is True.
50.
Identification of viruses using the electron microscope is not practical for laboratory diagnostic purposes.
Correct Answer
A. True
Explanation
The identification of viruses using the electron microscope is not practical for laboratory diagnostic purposes because electron microscopy requires specialized equipment and expertise. It is a time-consuming and expensive technique that is not routinely used in diagnostic laboratories. Instead, other methods such as polymerase chain reaction (PCR) or serological tests are commonly used for virus identification in laboratory settings.