Acellular Life MCQs with Answers
Which of the following is a key characteristic that considers viruses non-living?
They have DNA or RNA.
They can mutate.
They lack cellular structure.
They are obligate intracellular parasites.
The complete viral particle, consisting of a nucleic acid core and a protein coat, is called a:
Which component of a virus protects the viral genome from host nucleases?
Envelope
Tail fibers
Capsid
Glycoproteins
Viruses that attack bacteria are specifically known as:
Mycophages
Bacteriophages
Viroids
Prions
What type of nucleic acid is predominantly found in plant viruses?
Double-stranded DNA
Single-stranded DNA
Double-stranded RNA
Single-stranded RNA
An additional lipoprotein layer derived from the host cell membrane that surrounds some viruses is called the:
Capsomere
Nucleocapsid
Envelope
Matrix protein
The protein subunits that make up the capsid of a virus are called:
Peptidoglycans
Glycoproteins
Capsomeres
Lipopolysaccharides
Viruses that cause diseases like smallpox and polio are categorized as:
Bacteriophages
Plant viruses
Animal viruses
Fungal viruses
Which of the following viral symmetries is characteristic of Tobacco Mosaic Virus (TMV)?
Icosahedral
Polyhedral
Helical
Complex
David Baltimore's classification system for viruses is primarily based on:
Host specificity
Mode of replication and genome type
Presence or absence of an envelope
Size and shape of the virion
What is the primary function of glycoprotein spikes on the viral envelope?
Energy production for the virus.
Replication of the viral genome.
Recognition and attachment to host cell receptors.
Breakdown of host cell DNA.
Which of the following is NOT typically found in the core of a virion?
Viral genome
Enzymes for replication
Ribosomes
Reverse transcriptase
A virus with a polyhedral or spherical shape typically exhibits which type of capsid symmetry?
Helical
Filamentous
Icosahedral
Complex
The term "virus" originates from a Latin word meaning:
Small
Toxin
Poison
Invisible
Which of the following is considered a "living characteristic" of viruses?
Can be crystallized and stored.
Lack cellular structure.
Behave as inert infectious particles outside host.
Reproduce using host cell machinery.
Which type of virus is characterized by having a double-stranded DNA genome and a complex structure, often described as "tadpole-shaped"?
Plant virus
Bacteriophage
Animal virus with envelope
Retrovirus
The property of viruses that allows them to be crystallized and stored without losing infectivity is considered a:
Living characteristic
Non-living characteristic
Metabolic characteristic
Genetic characteristic
Which of the following is an example of an animal virus that is a double-stranded DNA (dsDNA) virus?
TMV
HIV
Adenovirus
Poliovirus
What is the specific enzyme found in retroviruses that converts their single-stranded RNA genome into double-stranded DNA?
DNA polymerase
RNA polymerase
Reverse transcriptase
Ligase
Viruses are obligate intracellular parasites because they lack:
A protein coat
A nucleic acid genome
Metabolic enzymes
Specific host receptors
Which of the following is a structural component found in bacteriophages but generally not in animal viruses like HIV?
Capsid
Nucleic acid
Tail fibers
Envelope
The number of capsomeres in a virus's capsid is:
Variable and changes with host.
Always 252 for all viruses.
Specific to the particular virus.
Determined by the host cell.
Which classification type would include viruses that cause Rous sarcoma and warts?
Bacteriophages
Plant viruses
Animal viruses
Fungal viruses
Which of these viral components is responsible for protecting the viral genome from denaturation by pH and temperature outside the host cell?
Tail fibers
Glycoproteins
Capsid
Reverse transcriptase
Why are non-enveloped viruses generally more stable and able to survive longer outside the host than enveloped viruses?
They have a stronger capsid.
Their genetic material is more robust.
Their outer protein coat is less susceptible to degradation than a lipid envelope.
They do not require a host to replicate.
Tobacco Mosaic Virus (TMV) is an example of a virus primarily classified by its:
Complex structure
Enveloped nature
Helical symmetry
Icosahedral symmetry
Which of the following enzymes is found within the viral core of retroviruses like HIV?
DNA ligase
RNA primase
Integrase
Helicase
The early evidence for viruses, demonstrated by Iwanowsky (1892) with tobacco mosaic disease, showed that the causative agent was:
A bacterium that could be cultured.
A toxin produced by plants.
A filterable agent smaller than bacteria.
A fungus visible under a light microscope.
Viruses are distinct from prions and viroids primarily because viruses possess:
A protein coat.
A nucleic acid genome.
The ability to cause disease.
Resistance to heat.
The causative agent of AIDS was identified in which year?
Which of the following describes the shape of the Human Immunodeficiency Virus (HIV)?
Tadpole-shaped
Rod-shaped
Spherical
Filamentous
What are the two main glycoproteins embedded in the outer lipoprotein envelope of HIV?
gp41 and gp160
gp120 and gp41
gp24 and gp17
gp120 and gp60
The enzyme responsible for converting the single-stranded HIV RNA genome into complementary DNA (cDNA) within the host cell is:
Integrase
Transcriptase
Reverse transcriptase
RNA polymerase
Which specific type of host cell does HIV primarily attack due to the presence of CD4 receptors?
B cells
Red blood cells
Helper T cells
Natural killer cells
In the HIV life cycle, after the double-stranded cDNA is formed, what is the next step?
Reverse transcription
Transcription of viral mRNA
Integration into host cell DNA
Assembly of new virions
What is the term for the integrated viral DNA within the host cell chromosome during the HIV life cycle?
Provirus
Prophage
Plasmid
Virion
Which of the following is an early symptom that may appear during the "Asymptomatic carrier" stage of AIDS?
Severe weight loss
Persistent night sweats
Swollen lymph glands
Opportunistic infections
The primary reason HIV leads to the development of AIDS is that it:
Directly causes skin cancer.
Produces toxins that poison the body.
Destroys T-cells.
Targets and destroys red blood cells.
Diseases that attack an AIDS victim due to a weakened immune system are known as:
Autoimmune diseases
Genetic diseases
Opportunistic diseases
Communicable diseases
Antiretroviral therapy (ART) for HIV is best described as a treatment that:
Completely cures HIV infection.
Boosts the immune system directly.
Controls the virus and prolongs life but is not a cure.
Prevents attachment of HIV to cells.
Which of the following is a common mode of HIV transmission?
Sharing food utensils.
Mosquito bites.
Casual contact like hugging.
Sharing used syringes/needles.
The HIV matrix proteins form a shell located:
Inside the capsid.
Between the envelope and the capsid.
Outside the envelope.
Embedded within the viral RNA.
Which stage of AIDS is characterized by persistent swollen lymph glands, night sweats, and persistent diarrhea?
Asymptomatic carrier
Full Blown AIDS
AIDS Related Complex
Incubation period
The uncoating of the HIV virion after entry into the host cell results in the release of:
Only viral proteins.
Viral RNA and enzymes.
Only viral DNA.
Entire intact virion.
Which of the following is NOT a common control measure against the transmission of HIV?
Screening blood for transfusion.
Sharing toothbrushes.
Not using used syringes/needles.
All of the options.
The lipid bilayer of the HIV envelope is primarily derived from what source?
Viral biosynthesis.
Host cell membrane during budding.
Host cell nucleus.
Environmental lipids.
The enzyme that facilitates the incorporation of HIV's double-stranded DNA into the host cell's DNA is:
Reverse transcriptase
Protease
Integrase
RNA polymerase
Which of the following conditions is considered an 'opportunistic disease' that may attack an AIDS victim?
Common cold
Influenza
Skin cancer
Measles
HIV is primarily named so because it directly leads to:
The formation of antibodies against itself.
A decrease in Helper T cells.
An increase in red blood cell count.
The direct destruction of all white blood cells.
What happens to the host cell after mature HIV virions bud off from it?
It becomes immortal and continues replication.
It immediately undergoes lysis.
It loses functionality and eventually dies.
It converts into a different cell type.
Which of the following is NOT a mode of HIV transmission?
Sexual contact.
Mosquito bites.
Mother to newborn during birth.
Blood transfusion with unscreened blood.
The severe weight loss and weakness are characteristic symptoms of which stage of AIDS?
Asymptomatic carrier
AIDS Related Complex (ARC)
Full Blown AIDS
Initial infection stage
The enzyme that breaks down large structural proteins into smaller, functional units during HIV's biosynthesis is:
Reverse transcriptase
Integrase
Protease
Ribonuclease
After HIV's single-stranded cDNA is synthesized, what enzyme disintegrates the viral genomic RNA?
Reverse transcriptase
Ribonuclease
Transcriptase
Protease
Which statement accurately describes the effect of Antiretroviral Therapy (ART) on HIV-positive individuals?
It eliminates the virus completely from the body.
It significantly delays the progression of the disease and can extend lifespan.
It is a one-time treatment that guarantees a cure.
It has no side effects and is inexpensive.
What is the role of gp120 glycoprotein in the HIV life cycle?
Fusion of viral and host cell membranes.
Integration of viral DNA into host genome.
Attachment to CD4 proteins on host cells.
Cleavage of viral proteins.
The process by which HIV enters the host cell after fusion of the viral envelope with the cell membrane is:
Exocytosis
Direct Fusion
Endocytosis
Active transport
Which stage of AIDS is diagnosed when the individual is highly infectious, and their HIV antibody test becomes positive, even if initial symptoms have disappeared?
AIDS Related Complex (ARC)
Full Blown AIDS
Asymptomatic carrier
Opportunistic disease stage
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